texts: How to tell the needed doping element for semiconductors?

texts: I was reading about a crystal that is a semiconductor, galena. I am confused on how to tell what elements are needed to dope it to make a p or n type semiconductor, as well as how to know which elements to use for doping other semiconductors.


texts: How do we explain shapes of molecules using molecular orbital theory or do we even do that?

texts:
How do we explain shapes of molecules using molecular orbital theory  or do we  even do that ?

While reading about the theories to explain chemical combination and stabilities of compounds I read about VBT and MOT and how when VBT failed to explain certain facts MOT was introduced but i do not know how do we explain shape of molecules using MOT as we do in case of VBT .


texts: Can Isopropyl β-D-1-thiogalactopyranoside be degraded into either 1-deoxy-galactose or just galactose?

texts:
This may be a silly question, but is it feasible that Isopropyl β-D-1-thiogalactopyranoside (IPTG) when acted upon by a beta-galactosidase could produce 1-deoxy-galactose or just galactose?

The reason I am asking is because I have a crystal of a beta-galactosidase that was exposed to 5mM IPTG for ~6 months at 4 degrees C for inhibitor studies.I have X-ray crystallographic data (Beta-galactosidase + IPTG) to ~1.8 angstroms and can easily place the galactosyl ring into my electron density, however, I cannot place the sulfur atom or the isopropyl group.

This would normally indicate that the sulfur and isopropyl atoms are disordered, however, the possible conformations are sterically restricted to one direction.

As such I am wondering if IPTG could, in fact, have been turned into either 1-deoxy galactose or galactose?


texts: What is the minimum pressure for existence of a liquid solution?

texts:
The minimum pressure for the existence of liquid solution is?

  $0.6\;\mathrm{atm}$
  $0.8\;\mathrm{atm}$
  $0.77\;\mathrm{atm}$
  $0.9\;\mathrm{atm}$

Although this seems to be an informative question, I want to know the process by which we get this answer.

I know that the critical pressure for a liquid solution is $p={ a\over {27b^2}}$ but what is the value of a and b in that case?

I expect an easy to understand answer for high-school level.


texts: How can chemical energy be stored in chemical things like candle wax, gasoline,...?

texts: I have learned about a type of storing energy is chemical energy. But energy isn't sth we can see, can touch. It just simply gives the ability to work. So how can energy be contain in such chemical things like above?


texts:
I need to determine the constitution of an organic molecule by several spectra like 1H NMR, 13C NMR, COSY, HMBC ,and HSQC.

Is it possible to get a HMBC crosspeak between the marked proton and carbon atom?


texts: What are the methods of fluoride removal from drinking water?

texts:
I would like to remove fluoride from my water supply.

Are there any methods, any test kits or water distillation units to remove fluoride from drinking water?

See also:

Is there any at home test for fluoride levels in your water, and what is the best water distillation unit?
A simple and easy way to neutralize fluorides in drinking water
Scientists Discover New Technique to Remove Fluoride from Drinking Water

Read More: http://www.trueactivist.com/scientists-discover-new-technique-to-remove-fluoride-from-drinking-water/


texts: What is the best approach to balance this equation? Why I cannot do it efficiently?

texts:
What is the best approach to balance this equation?
$$\ce{CO2 + H2O <--> C2H2 + O2}$$

I did it at first this way and I was not successful:
\begin{align}
\ce{4CO2 + H2O &<--> C2H2 + 3O2}\\
\ce{2CO2 + 6H2O &<--> 6C2H2 + 5O2}\\
\ce{12CO2 + 6H2O &<--> 6C2H2 + 5O2}\\
\end{align}

Should I start from right side or left? They say start from the most complicated molecule? If it is like that, then what is the most complicated one and why?


texts: Redox reactions: identifying what is oxidized vs reduced

texts:
$$\ce{SO4^2- + H2O2 + 2H+ -> SO2 + O2 + 2H2O}$$

In the above chemical reaction, I'm having trouble identifying what is oxidized and what is reduced.

My guess is: sulfur has reduced but I can't work out what has oxidised. My guess is the middle oxygen as it has lost two hydrogen atoms to $\ce{2H2O}$.


texts: Alkalinity measured by titration after degassing of CO2

texts:
I recently received some lab results from a sample which contained a lot of CO2, which degassed before the total alkalinity was measured by titration to a pH 4.5 end point. The best analogue for this sample would be a carbonated (sparkling) mineral water, which was measured 5 min after opening the bottle.
Is the total alkalinity, which was reported from these conditions correct? From my understanding, it is not, as degassing of the CO2 leads to a higher pH, which leads to a speciation shift from CO2 to HCO3-. This actually means, that more acid is required for the titration in order to reach the end point.
I have the feeling that there is a flaw in my argumentation as this would actually mean that for many samples, the actual total alkalinity cannot be correctly determined, or that you would have to measure the amount of degassed CO2 and correct alkalinity with a speciation calculation, which is not typically done.


texts:
What is the systematic name of carbonyl sulfide? My professor commented that the systematic name was "very odd" so he didn't bother to mention it. Is it really that odd? And what is it, actually?

I found the name "Thioxomethanone". Is that really odd? From my limited knowledge, I've seen the root "thiol" before in describing something with a sulfur in it. So at least the root doesn't seem weird. I also see "oxo." There's an O in OCS.


texts: Do dipole dipole interactions need to be added explicitly to vdW forces while doing DFT simulations for organic molecules?

texts: I  am modelling the adsorption of organic molecules on metal surfaces using plane-wave dft. While there is literature on how important van der Waals forces are for organic systems, and there are also some corrections to incorporate vdW forces into DFT (DFT-D, DFT-TS, and so on...); I was wondering if these corrections incorporate electrostatic dipole-dipole interactions within them (or do the dipole-dipole terms need to be added separately)?


texts: Is there a thermodynamic driving force for racemisation?

texts:
Why does racemisation occur?

My doubts are:

Is it due to entropy?
If it is due to entropy, how is the reduction of optical activity by racemisation a consequence of increased thermodynamic stability?
Will the entropy increase or decrease? I have learnt in thermodynamics that it is increase in entropy that favours thermodynamic stability.


texts: Predicting product ratio by rearrangement in Dehydration Reactions

texts:
I came across this question recently, which would have a clear major product. The OP has given satisfactory explanation for the product ratio, but wasn't sure about the major product. When I was looking for reference for better explanation, I show the following question in undergraduate textbook (Ref.1):

Dehydration of 2,2,4-trimethyl-3-pentanol with acid gives a complex mixture of the alkenes in the indicated percentages. Write a mechanism that accounts for each product.

I: 2,3,4-trimethyl-1-pentene, 29%
II: 2,4,4-trimethyl-1-pentene, 24%
III: 3,3,4-trimethyl-1-pentene, 2%
IV: 2,4,4-trimethyl-2-pentene, 24%
V: 2,3,4-trimethyl-2-pentene, 18%
VI: 2-isopropyl-3-methyl-1-butene, 3%

I thought it would be a good practice for our readers to predict the mechanism for the obtained product ratio and give explanation for the major products. Can anybody give a reasonable mechanism for this product ratio and explanation for why $\bf{I} \gt \bf{II} \ge \bf{IV} \gt \bf{V}$, and why $\bf{III}$ and $\bf{VI}$ are in such small amounts?
Late edit: It is evident that the textbook print had an error (Thanks Nisarg Bhavsar for the finding). The compound V is actually 2,3,4-trimethyl-2-pentene, not as 3,3,4-trimethyl-2-pentene in the print. I have corrected it now. Nonetheless, the question is still interesting.

References:

Robert J. Ouellette and J. David Rawn, “Chapter 9: Haloalkanes and alcohols Nucleophilic Substitution and Elimination Reactions,” In Organic Chemistry: Structure, Mechanism, Synthesis; Second Edition; Academic Press (an imprint of Elsevier): London, United Kingdom, 2019, pp. 255-298 (ISBN: 978-0-12-812838-1).


texts: The percentage of ingredients in a glass of tea

texts: When a pot, pitcher, glass, etc of tea is brewed, how do I find the exact concentrations of tea and water in the end result. I realize it depends on the amount tea and water used when brewing. Is it still called tea, albeit weak tea, when the water is more prevalent in the water to tea ratio?


texts: What is the Major product in free radical halogenation of Alkanes. (Between 3°,2°,1°)

texts:
In Free Radical Halogenation in presence of sunlight, a no. Of products are possible.

Due to higher stability of a 3°(Tertiary) radical, 3° products should be favored. But another factor that comes is that the formation of 3 ° radicals also leads to higher disproportion products. (Radical Disproportion- https://en.m.wikipedia.org/wiki/Radical_disproportionation)

Now, if i look at the intermediate, a higher no. Of Tertiary Radicals should form. But a lot of them will undergo radical disproportion as it is fastest in tertiary radical.

So is there any clear order of what product should be major or does it vary from case to case?


texts: I'm trying to verify the integrity of my cheap "24k gold" leaf

texts:
In what acid would a combination of gold and copper only dissolve the copper, but leave the gold?

I've been googling around, and so far they follow very close to the same solubility rules - as in, it would react with both the copper and gold, and both were semi soluble.  If the compound is brightly colored that would help too.


texts: Relation between ionisation enthalpy and nature of bonds in boron

texts:
My notes given by institute states that:

  Due to small size of boron, the sum of its first three ionization enthalpies is very high. This prevents it to form $+3$ ions and forces it to form only covalent compounds.

How is the covalent nature of bond of boron related to the sum of its first three ionization enthalpies?

EDIT :- I am directly or indirectly asking to prove fajan's rule for boron.


texts: Time until completion for $n$-th order reaction

texts:
For an $n$-th order reaction, how to determine the time until all the reactants run out?

My approach is the following. The reaction kinetics is modeled by the differential equation

$$\frac{\mathrm d[A]}{\mathrm dt}= - k{[A]^n}$$

where $n$ is the reaction order, which can take values in the nonnegative integers and even in the rational and negative numbers. Suppose we have a chemical reaction similar to the following one

$$\ce{A -> B}$$

In this problem, I'll take an example $5$ equation with similar form with the equation above, and different order $n$. Assuming the $n$ value of the $5$ example is $1,2,0,-1$ and $\frac{1}{2}$, we will get these equations for the five example after we input the $n$ value and integrate the kinetic differential equation.

(reaction with 1st order) $\ln[A] = -kt + \ln[A]_0 $

(reaction with 2nd order) $\frac{1}{[A]} = \frac{1}{[A]_0} +kt$

(reaction with 0th order) $[A] = [A]_0 -kt$

(reaction with $\frac{1}{2}$ order) $2\left(\sqrt {[A]} - \sqrt {[A]_0}\right) = -kt$

(reaction with $-1$ order) $\frac{1}{2}[A]^2 = -kt + \frac{1}{2}\left([A]_0\right)^2$

what I was thinking is, if I want to determine the time until the reaction complete, then I will have to define $t$ when $[A]=0$ (note: I will call the time that needed to complete the reaction $t_\text{complete}$) which is not defined for reaction with 1st and 2nd order because it will involve $\infty$ value, in fact as much as I know, $t_\text{complete}$ will not be defined for $n \ge 1$, but we can calculate $t_\text{complete}$ for $n \lt 1$.

so for 0th order, the $t_\text{complete} = \frac{[A]_0}{k}$

for $\frac{1}{2}$ order, $t_\text{complete} = \frac{2\sqrt{[A]_0}}{k}$

for $-1$ order, $t_\text{complete} = \frac{([A]_0)^2}{2k}$.

my question. is all the reaction with $n \ge 1$ never complete? and is all the reaction with $n \lt 1$ is the only reaction that can complete?
and I know what I've done is just manipulating the rate law equation, but if this is correct, can the $t_\text{complete}$ that I got above determine the time that needed for order $n \lt 1$ to complete?


texts: Can we use potassium iodide as pH meter electrode storage solution.? If not then why?

texts: If KCl is not available can KI be used to store pH probe meters? Both are potassium salts.


texts: What is the chemical composition of a Rubbermaid Roughneck container and is it feasible for me to make my own molds?

texts: I'm looking for more information on the composition of a Rubbermaid Roughneck container.  The description says "Roughneck containers are made with a durable polyethylene material for a lifetime of durability and strength." The Wikipedia entry indicates that polyethylene is the most common type of plastic with chemical composition $\ce{(C2H4)_{n}H2}$. But if this is so how are these containers able to flex instead of break like other plastic containers as well as tolerate greater temperature changes? I have a project that requires a custom shaped material of similar attributes. How feasible would it be to make my own mold at home? The shape I want to mold is very simple: a very thin rectangle about 35 width and 23 length. Are the chemicals involved dangerous to work with?


texts: Calculating the pH of a solution of Ca(OH)2

texts:
A solution prepared by dissolving $2.8 g$ of lime, $\ce{CaO}$ in enough water to make $1.00 l$ of lime water ($\ce{Ca(OH)_{2(aq)}}$). If solubility of $\ce{Ca(OH)2}$ in water is $1.48 g$. The $p\ce H$ of the solution obtained will be:

[$\log 2 = 0.3$, Atomic masses are $\ce Ca$ = $40$ , $\ce O$ = $16$, $\ce H$ = $1$]

[Note : $\ce {Ca(OH)2}$ is considered to be a weak base because  of its low solubility but it is 100% dissociated]

(A) $12.3$

(B) $12.6$

(C) $1.3$

(D) $13$

My attempt:As $2.8g$ of $\ce {CaO}$ dissolves in $1l$ water the molarity of the solution is 0.05M. So,the concentration of OH- ions in the solution is $0.1M$.So $p\ce {OH}$ is $1$ and hence $p\ce H$ is $13$. But, the answer is given to be $12.6$.What am I doing wrong?


texts: Why are bonded ions more stable than separate ions?

texts: I was reading on the Born-Haber cycle when I encountered a problem. The textbook seemed to suggest that since energy must be supplied to separate an ionic compound into it's composite ions, then the ions are more stable when they are bonded than when they are separate. My question is why?


texts:
Aren't alpha halo carbonyl compounds extremely fast and reactive via $S_N2$ (the fastest i guess)? If this is so, why isn't the major product in the Favorskii rearrangement an alpha hydroxy carbonyl compound?

And if the alpha carbon(to which the halide is attached) is tertiary, there should be a high chance of an elimination product via $E_2$ (leading to the formation of alpha beta unsaturated carbonyl), right?


texts: Change of electron spin in Carbon after Hybridization?

texts:
During bond formation in Carbon, one of the electrons from the 2s orbital jumps to one the empty p orbitals creating a hybrid orbital as seen in the figure below.

Now clearly one electron from the 2s orbital jumped to the 2pz orbital.
But what happened to the spin?
Before hybridization, one electron had an opposite spin, but after hybridization all electrons have the same spin.
Almost everywhere the same thing is shown.
Did the spin of the promoted electron get reversed?


texts: What kind of solvents favor elimination reaction?

texts: This question is confusing and I can’t seem to find a answer to this. The question is what solvent promotes E2 and E1 reactions? My teacher says that methanol as solvent with strong base favors E2 over Sn2. But she never explained why. Also she keeps using methanol as the example which is confusing. Can anyone please elaborate on this?


texts: Calculate the second ionization energy for the Mg from the following data?

texts:
here is a problem :

What I did " as shown in the picture below "

I rewrote the information given in terms of reactants and products ( equations )// in Part 1

Then I used the Hess law to obtain the desired result //in part 2

in part 3 // I added and cancelled the terms that appear in both sides

but I left with $O_{(g)}$ !! and the enthalpy is 1192 which is inconsistent with the correct value 1442 !!

What's wrong?


texts: Why does dichloridobisethylenediaminecobalt(III) have only three optical isomers?

texts:
Sorry for the bad drawing and having $\ce{NH}$ instead of $\ce{NH2}$

In the first structure, the chlorine atoms are in trans position on the plane.

In the second structure, the chlorine atoms are in cis position on the plane.

In the third structure, one chlorine is in the plane and the other chlorine is occupying one axial position.

Now all three of these will have one enantiomer making the number of isomers in total $6$.

So $\ce{[Co(en)2Cl2]+}$ should have $6$ optical isomers, but the answer in the book says that $\ce{[Co(en)2Cl2]+}$ has $3$ optical isomers. How?


texts: If the atomic number is # of protons, why does emission of a beta (electron) particle increase the atomic number?

texts:
Atomic number: the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table.

Beta emission:

$$\ce{^14_6C -> ^14_7N + ^0_{-1}\beta}$$

Why does emission of an electron increase the atomic number, when the atomic number is the number of protons, not electrons?


texts:
I want to make sure I understand this technique. I am reading information from this website.

From what I can understand, you have it set up like a galvanic cell, but in the middle of the wire connecting the electrodes you have a voltmeter which measures the current (converting it to potential? using V=IR?) but doesn't let any through to the other electrode so no reaction can happen. So the electrons at one electrode can still sense the potential difference between them but the voltmeter blocks them from travelling all the way through the wire? The potential you get is proportional to the concentration of analyte you are measuring according to the Nernst equation.

Please let me know if what I have said is correct or if I have misunderstood.


texts:
I am being asked by a colleague if the Polyvinylpyrrolidone (PVP) we buy in our lab is "USP 26" or "USP 42". I've never heard those terms before. I searched up online but found nothing.
I'm sure its something concerning the US Pharmacopeia, but I've found their site to be extremely walled up and unhelpful.
Can anyone tell me what do those terms mean, and how to find out if my PVP is either? The manufacturer's Safety data sheet didn't seem to mention it.
Note: I don't work at a food grade or drug grade lab. I'm also not in the USA.


texts: Determining the boiling point of a substance given the triple point and critical point

texts: If I have the pressure and temperature of a substance in its triple point, as well as its pressure and temperature in the critical point, how can I determine the boiling point of the substance at 1 atm of pressure?


texts: Does the outcome of aromatic nitrations depend on the concentrations of nitric acid and sulfuric acid?

texts: I came across a few equation and observed that when concentration of the $\ce{HNO3}$ and $\ce{H2SO4}$ with benzene ($\ce{C6H6}$) or its derivative varied the product changed. I did not perform any experiment and all of this I ask here is from the stuff I read in various books.please tell me about this nitrating solution and give me all the cases if possible.


texts: Why does a gas' ability to absorb infrared radiation affect its potency as a greenhouse gas?

texts: My book says that the ability of a gas to absorb infrared radiation affects its potency as a greenhouse gas, but I don't understand why. So what if a gas is able to absorb a lot of IR? How does that affect its potential as a greenhouse gas?


texts: REDOX spontaneity using electrode potentials

texts:
For this question, I thought the correct answer is A, because if we look at the electrode potential, that of iron(III) is higher than that of iodine, therefore the equilibrium for $\ce{Fe^3+}$ will favor the RHS, and shifts to the right, and therefore iodine will go in the opposite direction. Therefore A would be correct.

But the correct answer is D. Using the same logic, I can see it is also correct, but why isn't A correct then?

Thank you for any ideas in advance and sorry for the trivial question.


texts: In the case of an AA Alkaline battery, what actually happens inside the battery once it is fully discharged? What components of the battery change as we use it?


texts: Thermal equilibrium in reversible processes

texts:
In whatever resources I have consulted to study reversible thermodynamic processes, a common statement seems to be :

The system and surroundings (if the boundary allows) are in mechanical ($P_{sys}=P_{surr})$ and thermal $(T_{sys}=T_{surr})$ equilibrium at all instants.

However, in various answers on the Chemistry stack exchange, and in physical chemistry by peter atkins, it is claimed that the "surrounding" is an infinite reservoir: so the temperature can be assumed to be constant.
1.Is this not contradictory to the "thermal equilibrium" I mentioned in the beginning?
2.Thermal equilibrium of a system with its surroundings means that the entropy change of the surroundings , should be given by $\int\dfrac{-dq_{sys}}{T_{surr}}$. However, everywhere, this equation is simply given as $\dfrac{-Q_{sys}}{T_{surr}}$, which seems to be explained by the claim that the Temperature of the surroundings doesnt change. This equation, according to me should be applicabe only to Irreversible processes happening quickly. (or to isothermal processes).
so what exactly should we consider: $T(sys)=T(surr)$ at each instant, or $T(surr)$=constant?


texts:
I argued with my lecturer when he is saying that during the calculation of oxidation number, and your answer give you like 3.46 you can approximate it to whole number, I know tell him NO that if the answer is in decimal that means your calculations is wrong, he now tell me to go and research on my thought.
So please can anyone help me out


texts:
A point was raised about arrows used in a chemical reaction. I think we can all agree that $\ce{->}$ arrow in the reaction

$$\ce{A + B -> C} \tag{1}$$

means that the reaction goes in one direction. But what of

$$\ce{A + B <-> C} \tag{2}$$

$$\ce{A + B <=> C} \tag{3}$$

$$\ce{A + B <--> C} \tag{4}$$

$$\ce{A + B <=>> C} \tag{5}$$

$$\ce{A + B <<=> C} \tag{6}$$

Is there any IUPAC or American Chemical Society guideline about how double arrows are supposed to be used?

Examples of usage:

  (1) Used for example:
  "Removal of Triphenylphosphine Oxide by Precipitation with Zinc Chloride in Polar Solvents",
  Donald C. Batesky, Matthew J. Goldfogel, and Daniel J. Weix,
  J. Org. Chem., 2017, 82 (19), pp 9931–9936

  "Cation Radical Accelerated Nucleophilic Aromatic Substitution via Organic Photoredox Catalysis",
  Nicholas E. S. Tay and David A. Nicewicz*
  Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
  J. Am. Chem. Soc., 2017, 139 (45), pp 16100–16104

  (4) Used for example:
  "Cation Radical Accelerated Nucleophilic Aromatic Substitution via Organic Photoredox Catalysis",
  Nicholas E. S. Tay and David A. Nicewicz*
  Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
  J. Am. Chem. Soc., 2017, 139 (45), pp 16100–16104

Previous questions in Chemistry:

In his answer user Chemgoat noted that this question had been asked before:

What are the correct equilibrium arrows?

A comment on that question points to yet another

What is the difference between "reaction in both directions" and "equilibrium"?


texts: Why are acid-base reactions so exothermic?

texts: If I mix sulfuric acid with sodium hydroxide, the solution really heats up. Could someone explain why acid-base reactions are exothermic from a molecular perspective?


texts: Rate of catalytic hydrogenation of alkenes

texts:
What does the rate of catalytic hydrogenation of alkenes depend upon? What'd be the increasing order of rate towards catalytic hydrogenation of the following alkenes, A (2-methylpropene), B (cis-but-2-ene), and C (trans-but-2-ene)?

I suppose this has something to do with sterics and orientation - as catalytic hydrogenation is a surface phenomenon (occurs on surface of metal catalyst with adsorbed hydrogen), but I'm not sure about the above order in particular (I don't think a clear comparison can be made without looking at data, as the alkenes are quite similar), and the factors on which rate of hydrogenation of hydrocarbons depends in general.


texts: What happens if you add NaCl during the neutralization reaction between HCl and NaOH?

texts:
In class, I was taught that $\ce{NaOH}$ and $\ce{HCl}$ react completely (no equilibrium). I get the equation: $\ce{NaOH + HCl -> H2O + NaCl}$.

However, if I were to add a lot of $\ce{NaCl}$ to the solution, would some $\ce{NaOH}$ and $\ce{HCl}$ be formed according to Le Chatelier's principle?


texts: How to measure ozone output of an ozone generator using chemical methods

texts:
I have the need to optimize an corona discharge based ozone generator. There are certain variables like frequency and voltage which I can change.

The easiest way would be to use an ozone analyzer – however these things are quite expensive and over my budget currently.

I have tried certain ways to get a hold on numbers but failed so far.

Example: I used activated charcoal to convert the $\ce{O3}$ to $\ce{CO2}$ and tried to measure the $\ce{CO2}$ ppm, however it turned out that the activated charcoal did absorb the $\ce{CO2}$, so this measurement did not work..

Is there a easy to do chemical way to react the $\ce{O3}$ with something, that can be measured/done by a hobby chemist? My aim is to find at least a setup with the maximum ozone output. If it is possible to calculate how much grams ozone were produced it would be even better.


texts:
Why does ionization energy increase as we go from left to right in a period?

In my textbook, the explanation is as follows:

"This is consistent with the idea that electrons added in the same principal quantum level do not completely shield the increasing nuclear charge caused by the added protons. Thus electrons in the same principal quantum level are generally more strongly bound as we move to the right on the periodic table, and there is a generally more increase in ionization energy values as electrons are added to a given principal quantum level."

This, however, doesn't make any sense to me. From what I understand, in a stepwise ionization process, it is always the highest-energy electron (the one bound least tightly) that is removed first. So when we go more to the right in the periodic table, there are more electrons, and thus much more possibility for these to shield the outer electron from attraction to the nucleus. This would make it easier to remove that outer electron, and so I would say the opposite: the ionization energy should lower when we go to the right.

So can someone explain to me why this is not so? Thanks for any clarifications.


texts:
What is the reason for writing prefixes like di and tri in front of prefixes of alkyl or functional groups ?

For example in 2,3-Dimethylpentane we write 2,3 which is the location of the methyl group in the parent chain but then we also write Di to indicate the presence of two methyl groups.

I do not understand why we write Di, isn't it obvious that if there are two locants given then there will be two methyl group ? one methyl group is not going to be present at two places simultaneously.

Ok now lets assume for a second that writing Di is somehow useful, then
in 2,2-Dimethylpentane why we write 2,2 ? for me it is obvious that if there is Di before the methyl and only one locant is given then two methyl groups will be present at that location.

To summarise :

In 2,3-Dimethylpentane why we write Di if we have already written two locants to indicate the location of two methyl groups ?
In 2,2-Dimethylpentane if we write Di then why we write 2,2 ? I think only 2 is suffice here.


texts: How is the dissolution of acetic acid that makes its aqueous solution a poor electrolyte?

texts:
I'm having a difficulty understanding the following quote from Wikipedia - Dissociation:

  Acetic acid is extremely soluble in water, but most of the compound dissolves into molecules, rendering it a weak electrolyte.

To what (non-ionic) molecules can acetic acid be dissolved? If the answer is $\ce{CH3COOH}$ then in what way is it extremely soluble, if it dissolved to itself?


texts: Are there any free phosphorus-31 NMR spectral libraries?

texts: I know that there are some sites like Sigma Aldrich and AIST for $\ce{^1H}$ NMR and $\ce{^13C}$ NMR, but was wondering if there were any free sites to compare $\ce{^31P}$ NMR spectra?


texts: Why are there distortions in electron cloud in molecules? How does increase surface area amplify these distortions?

texts: In the physical properties of hydrocarbons,it is said that branched hydrocarbons have relatively less boiling point than it's linear form. From what I have learnt is that it is due to the increase in the surface area of the molecule which increases the intermolecular force. Now, this intermolecular force is the london dispersion force which happens because of the instantaneous distortions in electron cloud. This means the more the surface area of contact the more the ease of these distortions in electron clouds. This explains the strength of intermolecular force of branched and linear form of hydrocarbons and thus the difference in boiling point. But why there are distortions in the electron clouds? Why surface area has to do with these distortions?


texts: Will ice cream freeze faster with frozen brine or adding salt to ice?

texts:
I've been making some ice cream without a ice cream maker, using salt, ice, mixer and steel canister since I can't get a ice cream machine around here and its fun. It works pretty good but it seems slower than a simple ice cream machine that uses a freezer bowl. And the freezer wall volume seems smaller than the amount of ice I use.

Will using a frozen brine (if I can even freeze it) or liquid cool faster than
using frozen ice and then adding salt to melt it and lower the temperature? whats the difference? Is temperature all the matter? (liquid brine at -10c vs ice at 0)
any other factors that can contribute to the time it takes to freeze the mixture?
Any idea what coolant those bowls use? (seems to freeze at freezer temps).


texts: According to the theory of London dispersion forces, intermolecular forces are created in non polar substances by induction of instantaneous dipole to neighbouring molecules. If that is the case then when we mix water and oil, water being polar should induce polarity in oil and they should mix. But they don't. Doesn't water induce polarity to oil? Do I have a false concept or something.


texts: Is there a difference between potassium manganate and permanganate?

texts:
Is potassium manganate the same as potassium permanganate?

Also, I have seen potassium manganate written as potassium manganate (VII) or potassium manganate (VI).

What do the roman numerals stand for?


texts: Calcium carbonate and hydrogen peroxide reaction

texts: In application of hydrogen peroxide to soil and groundwater to remediate petroleum contamination, how will the naturally occurring limestone react with the peroxide, thereby reducing the effectiveness of the application.  Would calcium peroxide be more suitable.


texts: Why is hexafluoridocobaltate(III) the only common high-spin cobalt(III) complex?

texts: Almost all $\ce{Co^3+} (\mathrm{d^6})$ complexes are low spin, including $\ce{[Co(H2O)6]^3+, [Co(ox)3]^3–, [Co(NH3)6]^3+}$ and $\ce{[Co(CN)6]^3–}$. The only common high-spin cobalt(III) complex is $\ce{[CoF6]3–}$. Why is the hexafluorido complex in a high-spin state?


texts: How to find the potential of a mixed Iron/ Cer solution?

texts:
Given the following half-reactions:
   \begin{align}
    \ce{Ce^{4+} + e^{−} &-> Ce^{3+}} & E° &= \pu{1.72 V}\\
    \ce{Fe^{3+} + e^{−} &-> Fe^{2+}} & E° &= \pu{0.771 V}\\
 \end{align}
   A solution is prepared by mixing $\pu{3.0 mL}$ of $\pu{0.30 M}$ $\ce{Fe^{2+}}$ with $\pu{2.0 mL}$ of $\pu{0.12 M}$ $\ce{Ce^{4+}}$.

  What is the potential of a platinum electrode dipped into the resulting, equilibrated, solution (relative to SHE)? Calculate $\ce{[Ce^{4+}]}$ in the solution.

My attempt at solving the problem (which was incorrect):
First to find the potential (relative to SHE):
\begin{align}
E&=E^\circ-0.05916\cdot\log(\ce{Fe^{2+}/Fe^{3+}})\\
0.771&=E^\circ-0.05916\cdot\log((3\cdot0.3)/(3\cdot0.3 + 2\cdot0.12))\\
E^\circ&=\pu{0.7649 V}\\
\end{align}
I don't think this is correct.

Then:
I am not sure how to find $E^\circ$ cerium or how to find $\ce{[Ce^{4+}]}$.


texts: I'm confused about why hydrophobic molecules, which do not have high polarity, would have a tendency to attract and cluster with themselves. It is easier to understand the hydrophilic as long as one believes that positive charges attract negative charges. Anyone have any insights?


texts: What makes for a good 'swimmer' in order see the filling level of Xenon gas in a vessel?

texts: Most foams will probably get heavier due to diffusion. Is there glass balls this thin?


texts: Biochemical conversion of ethanol to acetic acid

texts: I have questions about the involvement of the electron transport chain (ETC) in the biochemical conversion of ethanol to acetic acid. In which of the reaction steps is the ETC employed?


texts: Why does mmHg persist in organic chemistry?

texts:
In most areas of chemistry, standard units are adopted - we never would think to use ounces (even American chemists resist) BUT even in modern journals or textbooks, we commonly still see the unit mmHg used. Why is this the case and why have people not moved to adopt SI units in this situation?

To give an example, consider the "Purification of Laboratory Chemicals" book that is often referenced here. Many distillations are given using pressures in mmHg.


texts: I'm making some graphs and I have to label the axes. I want to be extra careful and put the units in even though the meaning of $\text{pH}$ is well known. But I have a problem (though a simple one): $\text{pH}$ is a minus logarithm (base 10) of concentration of hydrogen ions (or rather their activity). What is the unit then, is it $[-\log(\text{mol}/\text{L})]$? What should I write, could you help me?


texts: Calculate inert molar flow rates in absorption column

texts:
In an absorption column the absorption of $\ce{CO2}$ from air to water is being studied. The in-flow of water is $\pu{5 dm3/min}$, the in-flow of air is $\pu{4.5 dm3/min}$ and the $\ce{CO2}$ flow is $\pu{0.8 dm3/min}$.

I want to calculate the inert molar flow rates, the amount $y_A$ of $\ce{CO2}$ in the inlet gas-stream and the  amount of $\ce{CO2}$ on inert basis $Y_A$.
I am unsure as to what is actually meant the inert molar flow rates. From what I have understood it is simply that I assume that the water and carbon dioxide are inert and use the ideal gas law to calculate the volume that $\pu{1 kmol}$ of gas occupies and then take the flow rates given divided by that volume.
So, from the ideal gas law, I get that the volume of $\pu{1 kmol}$ gas, which is:
$$V = \frac{nRT}{P}= \frac{1 \times 8.314 \times 298}{101.3} = \pu{24.46 m3}$$
Converting the air flow rate from $\pu{dm3/min}$ to $\pu{m3/h}$ and dividing by this volume gives:
$$\frac{\pu{0.0045 m3/min}}{\pu{0.0167 h}} = \pu{0.269 m3/h}$$
Then,
$$\frac{\pu{0.269 m3/h}}{\pu{24.46 m3}} = \pu{0.011 kmol air/h}$$
And then that would be my inert molar flow rate of air and I would do the same with water. Is that correct?
For the amount $y_A$ of $\ce{CO2}$ I am unsure as to how to calculate that but I know that once I have that I can calculate $Y_A$ using the equation:
$$Y_A = \frac{y_A}{1-y_A}$$
Could someone please tell me if my understanding of inert molar flow rates are correct and how I can calculate $y_A$?


texts: How to eliminate electrostatic charges from titanium dioxide powder

texts:
I have synthesized $\ce{TiO2}$ nanoparticles via sol-gel method and I need to calcine it at elevated temperatures for the crystal phases formation. The powder is very highly charged and not only difficult to work with but I also lose significant amounts as it gets repelled by quartz glass and other tools and fly all over the places.

Is there a way that I can alleviate the repulsive forces between the powder and the tools that I use?


texts:
I was reacting pure sodium and tap water, and at one point I put some splattered sodium back into the water. I observed fumes that reacted with my respiratory system, producing a burning sensation.

I read that it is possible to produce sodium oxide fumes from sodium hydroxide at high temperatures (the sodium did burn at the end, producing an orange flame).

My question is what could be the chemical composition of these fumes?


texts: Grapefruit and sugar gelatin like substance

texts:
More or less I am trying to figure out how this reaction occurred, so I can reproduce it.

On a plate I had an excess amount of sugar with a fair amount of grapefruit juice which was stuck to the plate. I filled the plate with water and left it for a little over 24 hours. When I finally came back to do the dishes, I poured the contents of the plate into the sink only to find that the bottom of the plate was covered in this slime very similar to clear gelatin. This slime was about as thick as honey, but was not sticky in any way, and was completely clear.

What could have caused this?


texts: Defining the partial pressure equilibrium concentration

texts:
First off, I am not a chemist. I'm an engineer with an interest in thermodynamics for engine simulation for the basis of emissions. So if I have asked something stupid, this will be why.

So I am trying to work out the partial pressure equilibrium constant for dissociation of CO2 to carbon monoxide and oxygen, to then move onto multiple reactions to calculate thermal NOx using the extended zeldovich mechanism. Now from engineering textbooks, $K_p$ is used as the partial pressure of the reactants, divided by the partial pressure of the products. However, from chemistry definitions, it is the other way round. (Partial pressure of products over reactants.)

My question is, can both be used, or is there a trick necessary to be able to this I have missed? The math works out a bit nicer the engineering way, but I want it to be correct obviously.

I have checked all my engineering books and found that indeed, it is defined as products divided by reactants. However, I found the bit that is confusing me, just it was hidden behind math.

For calculating the standard Gibbs free energy change, is that always sum of products minus sum of reactants?

I've done the calculations, and the only way I can get the math to agree is sum of reactants – sum of products:

From "Transport Fuels Technology"

$$K(\ce{CO2}) = 3.0549$$

From JANAF Tables

$$
\begin{align}
ΔG_\mathrm{f}^\circ(\ce{CO2}) &= -395.461 \\
ΔG_\mathrm{f}^\circ(\ce{CO}) &= -367.826 \\
ΔG_\mathrm{f}^\circ(\ce{O2}) &= 0
\end{align}
$$

$$ΔG^\circ = -RT\ln K$$
$$\frac{ΔG^\circ}{-RT} = \ln K$$

$$
\begin{align}
K &= \exp{\left(\frac{ΔG^\circ}{-RT}\right)} \\
  &= \exp{\left(\frac{27635}{-8.314\cdot 3000}\right)} \\
  &= 0.330
\end{align}
$$

Or reverse $ΔG^\circ$:

$$
\begin{align}
ΔG^\circ &= \sum ΔG_\mathrm{f}^\circ (\text{reactants}) - \sum ΔG_\mathrm{f}^\circ (\text{products}) \\
  &= -395.461 - (-367.826) \\
  &= \pu{-27.635 kJ mol-1} \\
  &= \pu{-27635 J mol-1}
\end{align}
$$

$$ΔG^\circ = -RT\ln K$$
$$\frac{ΔG^\circ}{-RT} = \ln K$$

$$
\begin{align}
K &= \exp{\left(\frac{ΔG^\circ}{-RT}\right)} \\
  &= \exp{\left(\frac{-27635}{-8.314\cdot 3000}\right)} \\
  &= 3.028
\end{align}
$$

which is in agreement with the book I am using.


texts: Horizontal symmetry plane of cis-dichloroosmiumtetracarbonyl

texts:
Consider the molecule $\ce{Os(CO)4Cl2}$ with a drawing given below via Chemtube3d:

I thought in this molecule, if I drew a horizontal plane, then a $σ_\mathrm{h}$ would be present i.e. A ‘horizontal’ mirror plane is perpendicular to the principle axes seeing as the mirror would, in my view, cut the atoms in half so the top would be the reflection of the bottom.

However, my professor said in a lecture that this molecule shown here does not have $σ_\mathrm{h}$ and I'm slightly puzzled as to why.

Why does this molecule not have $σ_\mathrm{h}$ plane?


texts: Nuclear zero-point energy and quantum delocalization effects of water molecules

texts: What do we mean by "Nuclear zero-point energy" and "quantum delocalization effects" of water molecules ? It's said that without these effects "water" becomes somewhat unbounded, which is not very well understandable to me. Can you please help me to clear my doubts.


texts:
This is the structure of carvone, with the chiral carbon noted by *.

I don't understand why this is a chiral carbon, to my understanding a chiral carbon is a carbon with 4 different chemical groups attached to it.

In the molecule, the chiral carbon is surrounded by $\ce{H}$, $\ce{C(CH3)=CH2}$ and two $\ce{CH2}$ groups.

Why are both $\ce{CH2}$ groups different and thus making that carbon chiral?


texts: Van der Waals interaction and magnetic dipole dipole interaction

texts:
I have a conceptual question that bothers me.

From what I understand, van der Waals forces are the primary source of inter-molecular interaction. There are three different possible origins for van der Waals forces: permanent dipole-permanent dipole (Keesom/short range) forces, the permanent dipole-induced dipole (Debije/short range) interactions and induced dipole-induced dipole (London/long range) forces. (Here we talk about electric dipole.)

We also have magnetic dipole dipole interaction which is $\propto \frac{m_1m_2}{r^3}(3\cos^3\theta-1)$ and has quantum mechanical origins such as Pauli's exclusion principle and exchange interaction and etc.

My question is: since both magnetic and electric dipole dipole interactions are interpreted based on vector model mathematical formulation and these interactions happen at atomic level and they are of a similar range, in what cases we consider interaction between electric charge or a dipole, and magnetic dipole?

Or in general, can magnetic dipole-dipole interaction happen along with electric dipole-dipole interaction in a systems?
When I read text books on inter-molecular forces (Israelaschvili, Cosgrov, etc) non of them talk about magnetic interactions. I wonder why.


texts: Reaction of Silicon Dioxide with Hydrofluoric Acid

texts:
I learnt that $\ce{SiO2}$(Silicon dioxide) doesn't react with any acid except $\ce{HF}$. So what is special about $\ce{HF}$?
Why does only $\ce{HF}$ reacts with $\ce{SiO2}$ even though $\ce{HF}$ has a very high bond energy compared to other acids in that group?


texts: How do I separate a graphene/graphite oxide and NaOH solution without centrifugation? (filtration didn't work)

texts:
The graphene oxide solution was made from electrolytic exfoliation of graphite electrodes in a 10M NaOH solution. Some graphene powder deposited on the bottom of the recipient but a brownish solution remained, even after the powder settled. Graphene oxide is believed to be the source of the brown color.

The solution still has a lot of the hydroxide present so evaporating the solvent also leaves that compound behind along with the brown crystals, so it's hard to identify if it is actually graphene oxide or just impurities.

Right now I don't have a centrifuge, and filtration didn't work, so how do I separate them?


texts: I am working with salophene iron[III] complexes. Unfortunately, my 5th ligand cannot be determined via MS. I performed a 1H-NMR in methanol, but it's not a suitable method for a paramagnetic compound. What is a reasonable approach. Should i work on optimizing the MS method or is there a suitable method for iron salophene complexes via NMR.


texts: Steric Effects in Friedel-Crafts Reactions

texts: I recently came across a Friedel-Crafts reaction happening between benzoyl chloride and mesitylene with $\ce{AlCl3}$ as a catalyst. Apparently this reaction doesn't occur due to steric effects even though the mesitylene ring is highly activated by the three methyl groups. This got me wondering whether the reaction between benzoyl chloride with two methyl groups at ortho positions and benzene with $\ce{AlCl3}$ catalyst would occur or not. Most importantly, my question is: where all do steric effects become the major factor in the reaction, and how do we identify that? Why is it so?


texts: Comparing adamantane carbon types for accepting OH using MM ForceField

texts:
I want to compare two type of carbons accepting OH in adamantane which I've shown below.

I know the blue position is preferred. But I wanna prove it with energy optimization and MM Forcefield. I thought it is related to transition state and corresponding carbocations. But MM+ ignores all charges.

How can I test it using ForceField softwares ?


texts: How much heat is gained/released based off of equation?

texts:
Using this equation,
$\ce{CaCl2(s) -> Ca^{2+}(aq) + 2Cl^{-}(aq)}$

and $\Delta H = - 325.0 \; kJ $

If you have 15.0 grams of the solid, how much heat is released or gained in kilojoules?


texts: Resonance Forms in Electrophilic Aromatic Substitution

texts:
In most diagrams for electrophilic aromatic substitution, the following is represented:

What happens to the other two resonance forms of the sigma complex? It seems like most of the time the first form is simply chosen to illustrate the return of aromaticity.

Suppose I switched the resonance structure in the second step to the following:


texts: Miscibility of pairwise miscible liquids

texts:
If you have a mixture of 3 (or more) liquids which are "pairwise miscible", but which don't react with each other, does that guarantee that the mixture will only have one layer?

By "pairwise miscible", I mean that for every combination of two substances in the mixture, they are miscible with each other, i.e. soluble in all proportions.

For example, ethanol/water/acetone.


texts:
I'm sorry if this has already been asked but I could not find it on a search here though I also could not determine how to search for the presence of two words ('ammonia' and 'aluminum')

I've read mixed results about whether using household ammonia on aluminum is damaging or not. In my case I want to use it to clean baking trays by putting some (~ 1 tablespoon to 1/4 cup) ammonia on the pan and cover it with a plastic bag and set it aside for hours or a day or so to allow it to soften the baked on grime. I also want to and am using it for a variety of other household and tinkering projects. I read on one site that it is a very bad idea to use ammonia on an aluminum bike frame because it will severally weaken it.

Does household ammonia damage aluminum?


texts: How can Arrhenius bases also be Brønsted-Lowry bases?

texts:
According to ChemGuide,

  The Brønsted-Lowry theory doesn't go against the Arrhenius theory in any way - it just adds to it.

According to Study.com:

  All Arrhenius acids and bases are also Brønsted-Lowry acids and bases.

This makes sense for Arrhenius acids, such as hydrochloric acid. Hydrochloric acid produces hydrogen ions when dissolved in water. Additionally, it donates a proton to water.

However, sodium hydroxide is an Arrhenius base, since it produces hydroxide ions when dissolved in water. However, sodium hydroxide cannot accept a proton to form $\ce{HNaOH+}$. So, how can it be a Brønsted-Lowry base? Similar reasoning can be applied to other Arrhenius bases, such as potassium hydroxide.


texts: Hybridization of oxygen in Nitrate ion and the location/bond of nitrogen's lone pair

texts:
I have tried to apply the rules and basics that I learnt so far. But I am confused about the hybridization of oxygen atoms which are making the single bond in nitrate ion.

Following are the steps I used. The average bond order of 4/3 makes the molecule unstable.

Based on the steps, the single bonds are made of $\ce{sp^3}$ of oxygen and $\ce{sp^2}$ of nitrogen, the bonds are sigma bonds. However that doesn't seem like the case. If I look at $\ce{HNO3}$ dissociation equation in the water, lone electron pair of nitrogen is entirely shared with (co-ordinative covalent bond) one of the oxygens making a single bond.

$\ce{ HNO3(aq) -> H+(aq) + NO3^{-}(aq) }$

But considering $\ce{NO3}$ ion individually, without thinking about nitric acid, I can't find the long pair to be in the same type of co-ordinative bond. Isn't there an unbonding sp2 electron with nitrogen (probably one from the lone pair)?

The other issue, why isn't oxygen hybridizing to be $\ce{sp^3}$ here? What am I doing wrong here?


texts:
I have a quest to explain a physical, chemical theory to kids of age 8-12.

The topic is "Ionization". We all understand from early experiments of Physics and Chemistry (the Millikan oil drop experiment) how a neutral atom in gas becomes a charged atom where radiation knocking the electrons out of the neutral atom.

Here's the story line I came up with. Can you guys please help me to make this a success and correct the wrong impressions, expressions and examples in the narrative?
I am open for any better examples.

There's a high-class (=high voltage) shopping mall area (=radio activity area metaphorically) in the country I am living right now. One particular shopping mall called ION. If you enter that shopping mall, you will shop and get excited (=charged) and spend your pocket money (=losing electrons) by the temptation (=radiation) from fancy shoppers around. Shopping means getting exposed to radiation.

Some shoppers are highly influential (=alpha rays with +2 charge) and there's a high tendency you will spend money (=lose electrons). e.g. Movie theater. You get excited even looking at it from far.

Some other shoppers are less influential (=beta rays with -1 charge). e.g. Junk food, a piece of cake you like to eat. You have to go near to see the food and then spend your money on it. The excitement of eating the food lasts for shorter period compared to the movie you watched. So the impact from movie is higher. You will talk about it in school for a week or two. Unlike the food you had and forgotten by the next meal.

The last type of shoppers are least influential (=gamma with 0 charge). e.g. Manga shop. You don't find it as exciting as watching a moving or eating favourite food. But you may go there as a matter of need (for a manga copy) or peer-pressure from your friends to buy manga and spend your money. You are kinda forced to get excited (=charged) to spend a buck on it.

So it's quite dangerous for you (=neutral atom) to enter or go near a shopping area (= radiation area) where you will be losing your money and get excited for nothing...


texts: Why does the lone pair of phosphine not contribute to its dipole moment?

texts: Unlike ammonia, the lone pair of phosphorous does not add to the dipole moment of phosphine. My textbook says this is due to the presence of lone pair of phosphorous in $\ce{PH3}$ in an s-orbital. I couldn't understand my book's explanation. How can the orbital of lone pair determine its contribution to the dipole moment?


texts: What is the role of size in formation of complex compounds?

texts:
In my textbook, these reasons are given as of why transition metals form a large number of complex compounds:-

Smaller size of metal ions
High ionic charges
Availability of d orbitals for bond formation

What is the use of the first reason, i.e small size? Shouldn't it be opposite? In interhalogen compounds too, in XYn, X should be of greater size than Y. So why opposite in case of complex compounds?


texts: If radium has such a long half-life, how can radon possibly be a threat to us?

texts: If the probability is so low that a radium atom will decay into radon at any given time (the half-life is over 1600 years), then there will be a low amount of radon produced, granted it will be produced for a long time. If this is so, how can radon possibly be dangerous to us?


texts: Multi-solvent recrystallization to extract solute from glycerol?

texts:
I have compound A contaminated with impurity B. Recrystallization in water would not yield pure compound A since impurity B is less soluble in it. The only solvent in which substances A and B have opposite solubility is glycerol. Compound A is soluble in it while impurity B is insoluble.

I would propose my first step to be heating the glycerol to minimize the amount of solvent needed to fully dilute compound A. I would then filter the solution to have my purified compound A in glycerol solution (impurity B would remain in filter).

As far as I have heard though, glycerol is not as easy to boil as water, being similar to cooking oil. Unfortunately, I don't have a vacuum distillation apparatus to extract the glycerol without caramelizing it.

I was thinking of slowly add anhydrous ethanol to (purified compound A + glycerol), since compound A is insoluble in it. I would expect multi-solvent recrystallization to occur as I add ethanol and lower the mixture temperature.

Would it work and does it seem to be the easiest method of purification at home?

For the curious: $A = \ce{KNO3}, B = \ce{K2SO4}$.
No, I don't want the $\ce{KNO3}$ to make a bomb, but to make a sugar rocket for model rocketry.


texts:
I was trying to determine the reaction mechanism behind the production of diethyl ether. Looking at the ethyl alcohol + sulphuric acid method, I have come to the following conclusions for the reaction steps:

The ethanol nucleophilic oxygen gets protonated by the addition of sulphuric acid. This is more favourable because of the high density of electrons surrounding the oxygen. The bond broken between the carbon and oxygen is also needed to form the bond with hydrogen.

Water is then released and the ethyl alcohol conjugate base is formed (H3C-CH2+). The remaining ethyl alcohol molecules can either react with the HSO4- or the ethyl conjugate... Since HSO4- is more stable than the ethyl conjugate, ethyl alcohol reacts with the ethyl conjugate. Carbon is more electronegative than hydrogen and is an electrophile. It is attracted to the oxygen from the ethyl alcohol and replaces the H, thus forming diethylether, H+ and H2O where the sulphuric acid essentially acts as a catalyst!

Am I correct in presenting the mechanism this way? If the sulphuric acid still remains in the solution, why does it not protonate the diethyl ether? Is it because the stability of the diethyl ether conjugate base is unstable?

Thanks


texts: Silicone based polymer that can be functionalised on one end?

texts:
I am looking for a silicone based polymer (think PDMS but I need to do some chemical reactions with it) where I can attach on one side (or both, I am not sure yet) another molecule that has a carboxylic acid at the end or an amine. Maybe some of you know of a PDMS derivative that's functionalised at the end?
Many thanks in advance.


texts: What is the chemical structure / hybridization of sulfuric acid?

texts:
I was looking at the chemical structure of $\ce{H2SO4}$.

Intuitively, I would have expected this molecule to be square planar in accordance with $p^2d^2$ or $sp^2d$ hybridization, but instead it is shown to be in a tetrahedral geometry consistent with $sp^3$ hybridization. Why is this?

I guess that an alternative way of asking this question is: What is the hybridization of the sulfur atom in $\ce{H2SO4}$?


texts: Equilibrium constant of a reaction whose order of forward and reverse reaction is not same

texts:
Suppose, a reaction is like,
$$\ce{aA + bB <=> cC + dD}$$
and that A, B, C, D all are gas.
Now it is known that:
$$K_c = \dfrac{[A]^a[B]^b}{[C]^c[D]^d}$$
Now if the forward reaction is second order and the reverse reaction is in first-order somehow then, how will this change.
I read some articles online but it was not actually clear that if all the reactants or products are in the same state like gas or aqueous then how $K_c$ or $K_p$ (for gas) will change depending on the rate of reaction or if they don't depend on that totally.
It will be helpful if one example is provided.


texts: Does Copper reacts with Sodium Sulfate solution?

texts: Okay I am trying to make a capacitor in which current collector is copper foil and electrolyte is sodium sulfate. Would this work? Do these two react with each other or not?


texts:
Bromination of an alkene in presence of water results in its mechanism in a cyclic bromonium ion and "afterwards $\ce{H2O}$ binds to the carbon atom surrounded by more electron donating groups."
This is what we learned in class and I couldn't understand why. Shouldn't an electron donating group decrease the "strength" of an electrophile?

Also to my surprise, in an exercise, $\ce{H2O}$ was added to the formerly $sp2$ carbon bonded to $\ce{-OCH3}$ which donates electrons by resonace in an alkene.
But $\ce{H2O}$ was added to the cyclic bromonium and not to the alkene directly! So why to care about  the resonance effect of $\ce{-OCH3}$?


texts: CSTR reaction cooling jacket - Transfer Functions

texts:
I have a CSTR where an irreversible exothermic liquid reaction takes place. Coolant is flowing in the jacket of the tank to regulate the temperature of the fluid in the reactor and control in this way the concentration of component A. The cooling jacket stays at a uniform temperature. An on-line infrared spectrometer with no lag is the sensor used to measure the concentration of component A. Reaction rate is given by r(t) = k(T(t)) Css.
The goal is to get all transfer functions between the input and output variables.


texts: How to calculate what temperature change in entropy for the reaction equal to the change in entropy for the surroundings given Enthalpy and entropy

texts:
A reaction has $\Delta H_\textrm{rxn} = \pu{-107 kJ}$ and $\Delta S_\textrm{rxn} = \pu{285 J/K}$. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings?

My thoughts:
I wasn't really sure if there was an equation that related the entropy and the enthalpy and would like to know if there is such an equation.


texts: Relating a compound's radii and unit cell dimensions

texts:
We're asked often to calculate the density of a crystal, and there is a known formula for that related to the unit cell volume.  Now, for simple geometric structures such as the bcc structure (and since it is close packed), I know how to relate the different radii of the constituent compounds with the unit cell's (unique in this case) dimension (the length a), but how do I relate it for such other complex structures?

In general given a certain crystal geometry (cubic , tetragonal , orthorhombic), how does one relate the unit cell dimension with the radii of the constituent atoms?


texts: What is the order of stability of the resonance structures of furan?

texts: I want to know which are the most stable furan resonance structures. I know that structure number 1 is the most stable, but which one comes after?


texts: Reaction of phosphorous acid (H3PO3) and potassium hydroxide (KOH)

texts:
For the reaction of phosphorous acid ($\ce{H3PO3}$) and potassium
hydroxide ($\ce{KOH}$), write (a) the balanced molecular equation
and (b) the net ionic equation. Note that phosphorous acid is
a diprotic acid.
$$\ce{H3PO3(aq) + 2KOH (aq) -> 2 H2O(l) + K2HPO3 (aq)} \tag{a}$$
$$\ce{H3PO3(aq) + 2 OH-(aq) -> 2 H2O(l) + HPO3^2-} \tag{b}$$

The answers are above. Can somebody explain why it is $\ce{K2HPO3}$ in (a)? I am familiar with monoprotic acid, and this is my first encounter of diprotic acid. Thanks.


texts: Help understanding the synthesis of HOCl

texts:
My goal is to add acetic acid to sodium hypochlorite to reach a ph of between 3.8-5.5 and produce hypochlorous acid. I’ll be using bromocresol green as a ph indicator. I was reading about how to synthesize it from an article here by the acidification of hypochlorite, which was noted to be the safest and most controlled way. My initial question was how do I calculate how much acid is needed to reach the specified pH range. However, other users noted that this may dangerously produce chlorine gas, in which case this experiment should be executed under a fume hood with care and proper safety precautions.
Figure 2 from the article notes the production of various byproducts of the reaction at different pH levels. It appears that chlorine gas is produced at both low pH and at high pH, but it is a bit confusing since it is overlapping with another line making it hard to understand.

Ideally, I'd like to reduce any production of Cl$_2$. Is there a way to do that? Anything to help me better understand this reaction is appreciated.
For the moderators,
I don't understand why this question was so poorly received and closed. It clearly lies within the allowed topics listed in the help center. Even though my question was about a potentially dangerous experiment, it is an important one nonetheless. I was able to learn an important detail concerning the safety of the experiment from this post. If anyone else was to follow down the same path as me, they should be able to google about it, see this question, and learn of the safety concerns as well. I think this question should be reopened to educate people instead of being heavily downvoted because OP is an inexperienced chemist trying a dangerous experiment, because that is not the case.


texts: I understand why solids and liquids are not included in the $K_{eq}$ expressions. However, I'm wondering what the $K$ value for a reaction involving only solid or liquid reactants and products looks like. Theoretically, it'd be 1 no matter what since $1^n = 1$. Is this right? Also, do all such reactions go to completion?


texts: Tight binding model with Extended Huckel Approximation

texts:
I've been reading Albright's Orbital Interactions in Chemistry. In the chapter on solids, he provided a general approach to find the band structure of a solid state system

Now if we are to model a one dimensional hydrogen chain, let $|1s(r)\rangle$ denote the $1s$ orbital centered at $r$. The band energy at each $k$ point will just be $e(k)=\frac{H_{11}(k)}{S_{11}(k)}$ according to the secular determinant. I then use a first neighbor interaction simplification, so $H_{11}(k)=\langle 1s(r)|H_{eff}|1s(r)\rangle+2\cdot\exp(ika)\langle 1s(r)|H_{eff}|1s(r-a)\rangle$ and $S_{11}=1+2\cdot\exp(ika)\langle1s(r)|1s(r-a)\rangle$.

It's worth noticing that assuming orthogonality of neighboring orbitals will set $S_{11}=1$, then $\langle 1s(r)|H_{eff}|1s(r-a) \rangle$ and $\langle 1s(r)|H_{eff}|1s(r)\rangle$ are just analogous to $\beta$ and $\alpha$ parameters in the simple Huckel model. But for the sake of realism I’m considering overlaps(the textbooks is also doing that) That is why the plots below show an asymmetric split with regard to hydrogen 1s ground state energy.

So far so good. I can even get a quick numerical estimate of $H_{11}$ using the extended Huckel approximation because then I just need to know the overlap integral between neighboring $1s$ orbitals. However, when I plot the result in Matlab it's different from the plot in the textbook:

Especially, the energy at the edge of the Brillouin zone is too positive. Anybody knows why that might happen? Thanks!


texts:
When a solid element is reacted with chlorine, a gaseous chloride of vapor density $68.75$ is formed. If this reaction is performed at constant temperature and pressure, the volume of the system reduces by $\frac{1}{3}$. What is the equivalent weight of the solid element?

I found out the molar mass of the gas $68.75 \times 2$. But don't know how to proceed from here?


texts: What can I  mix with hand sanitizer to make it heat up as I apply to/rub into my hands?  Something that doesn't affect the sanitizing.


texts:
I have recently started doing DFT calculations as part of my PhD. The general approach to DFT in my department appears to be that it is regarded as a tool for doing calculations, which need not be understood in detail. While I understand this to some degree, I however still feel the need to at least understand the basic theoretical ideas behind a DFT calculation. I am therefore using this post to summarize a few of my questions about DFT starting from the basic theory.

As I understand it, the formalism of DFT rests upon the Hohenberg-Kohn theorems, stating that the ground state properties of a many-body system are unique functionals of the ground state density, which furthermore minimizes the total energy functional $E[n(\mathbf{r})]$ of the system:

$$
E[n(\mathbf{r})] = T[n(\mathbf{r})] + E_H[n(\mathbf{r})] + E_{ext}[n(\mathbf{r})] + E_{xc}[n(\mathbf{r})]
$$

Here $T[n(\mathbf{r})]$ is the kinetic energy functional, $E_H[n]$ the Hartree functional and $E_{ext}[n(\mathbf{r})]$ the energy due to external potentials while $E_{xc}[n]$ is the unknown exchange-correlation energy functional, which encompasses the exchange and correlation effects of the many-body problem and must be suitably approximated by e.g. the LDA.

In practice DFT calculations are based on the Kohn-Sham approach, which makes the ansatz that there is a non-interacting system, which reproduces the density of the many-body system one wishes to describe. Consequently, instead of solving a many-body Hamiltonian, one solves a set of single-particle equations, the Kohn-Sham equations:

$$
(\nabla^2 + V^{KS})\phi_i(\mathbf{r}) = \epsilon_{i}\phi_{i}(\mathbf{r})
$$

with the Kohn-Sham potential given by:

$$
V^{KS}(\mathbf{r}) = V_{ext}(\mathbf{r}) + V_{H}(\mathbf{r}) + \frac{\delta E_{xc}}{\delta n(\mathbf{r})}
$$

The density is then readily evaluated as a sum over the occupied orbitals:

$$
\rho(\mathbf{r}) = \sum_{occ}\lvert \phi_{i}(\mathbf{r}) \rvert^2
$$

My main question is essentially, if anyone can walk me through how the above theoretical ideas are used in a concrete DFT calculation. Say, e.g., I want to calculate the ground state energy of some molecule. How does a DFT calculation proceed using the equations outlined above?

My own (partial) answer: The first step is specifying the energy functional, which relies on choosing a suitable approximation for the exchange-correlation functional. My guess is then that the next step is to solve the Kohn-Sham single-particle equations. To do one needs the Kohn-Sham potential, which must be found from the functional derivative of the total energy functional. I am honestly not sure if this is how a DFT calculator proceeds, but it seems like the only way to get the Kohn-Sham potential. Having solved the KS system, one can then calculate the electron density, which should then equal the density of the interacting system. However, I speculate that the procedure may involve some sort of self-consistency such that one should in practice make an iterative procedure to find the correct interacting density.

Assuming everything is correct so far, how does one then get the ground state energy? So far we have only calculated the ground state density and the energies of the Kohn-Sham orbitals are not physical energies of the system.


texts: How did Millikan measure the mass of these oil droplets?

texts:
I was reading the R.A. Millikan's oil drop experiment and the following part confused me:

By measuring the rate of fall, Millikan was able to measure the fall of the oil droplets (which were dropped through a tiny hole in the upper electrical condenser).

In Newtonian physics, the rate of fall (or velocity) of a freely falling body does not depend on the mass of the object. So, how did Millikan measure the mass of these oil droplets? Does anyone know the equations he used?


texts: Why does milk clot when it becomes yogurt? Is it only because of the decrease in the $\mathrm{pH}$ of milk? If it does so, what is happening when I increase the $\mathrm{pH}$ level? And by decreasing the $\mathrm{pH}$ level can I clot any type of liquid like milk?


texts: Predict the number and nature of bonds using Molecular Orbital Theory

texts:
I found the following question in a high school chemistry problem book:

According to Molecular Orbital Theory which of the following is true:
(A) In $C_2$ molecule both the bonds are $\pi$ bonds.
(B) In $C_2^{2-}$ ion there is one $\sigma$ and one $\pi$ bond.

Both of these are true. But how can one know this using Molecular Orbital Theory?
P.S.: I don't know anything about Quantum Mechanics as I am a high school student. My textbooks only provide a result-oriented explanation. I would appreciate if the answers keep this in mind.


texts: Are molecules on surface of liquid stationary due to surface tension

texts: Are the molecules which are on the surface of a liquid ie the molecules on the top film stationary ie not move about each other under steady conditions ie unlike molecules in the bulk because of surface tension and because surface acts like a stretched film and leaving or coming to the surface for any molecule requires gain or loss of energy ?


texts: Can % location of electron on metal or ligand be negative (EPR)?

texts:
Given an EPR spectrum of [Co(3-methoxysalen)(py)] :

and equations:
A(x) = A(iso) + B
A(z) = A(iso) - 2B
%Co in SOMO = B/B0
where A(x) and A(z) are hyperfine coupling constants measured from the spectrum and B0 = 7.6 mT, we have to calculate %Co. This is straightforward, but returns a negative percentage answer (-43%) - does this mean that there is no %Co in SOMO, or the value should be taken as an absolute and SOMO is in 43% based on the cobalt?
Thank you in advance for help.


texts: Can a reaction have more than one rate determining step?

texts:
There are many organic reactions in which two steps have comparable rates. Can we say they are both RDS?
For example, the rate of iodination of benzene and deuterated benzene is different even though the step is not considered RDS.


texts: If we are supplying energy continuously, why will the electrons jump down to the lower state?

texts:
We know in a flame test an electron goes into excited state. When it jumps down to a lower energy state, we can see the color of the flame if it's in our visible region.

My question: we are supplying energy continuously, so why will the electrons jump down to the lower state?


texts: My mechanism for this conversion is an intramolecular attack sn2 to displace Cl- anion. OH- can then attack this aziridinium intermediate, but will the nucleophile not attack preferentially at the most substituted site (where greatest positive charge resides i.e. tertiary center)? This gives the incorrect product?


texts: Is there any actually observed excited state of a "hypervalent" main-group molecule that actually involves d-orbitals?

texts:
It is well known that, even in periods 3 and higher, the bonding in so-called "hypervalent" main-group molecules nearly always do not involve d-orbitals, and I've heard that it's because the d-orbitals are just too high in energy.

I now have a question: if the energetic difference is the only problem, then can bonds involving d-orbitals exist ("exist" as in "actually be observed") in excited states of "hypervalent" molecules?

For a more concrete example- do the bondings in sulfonate groups in Brilliant Blue FCF and indigo carmine get "elevated" from S(-O)3 to S(=O)2(-O) (charges omitted and S=O bonds involving sulfur's 3d orbitals) as they absorb red-light (opposite of blue) photons, and, if they do, to what extent?


texts: Separating lanthanides using ion-exchange method

texts:
Following statements are on Separation of rare earth metals (lanthanides) via in-exchange method

  The tripositive ions are strongly sorbed by cation exchange resin: $\ce{La^{3+}}$, the largest is most strongly held; $\ce{Lu^{3+}}$, the smallest is least strongly held. Elution of $\ce{HCl}$, therefore removes $\ce{Lu^{3+}}$ first and $\ce{La^{3+}}$ last.

Generally, the smallest cation forms the strongest bond, so shouldn't $\ce{Lu^{3+}}$ be most strongly held? The most common cation exchangers, such as $\ce{RSO3^-Na+}$, where $\ce{R}$ is a cross-linked matrix are hard bases, so shouldn't according to HSAB principle also, $\ce{Lu^{3+}}$ be most strongly held?

Follow-on excerpt,

  The separation is however not good, particularly between the heavier lanthanides, but is markedly improved by the addition of complexing agents such as $\ce{EDTA}$, or ammonium citrate/citric acid buffer to the eluting solution. The citrate ion complexes most strongly with the smaller elements, i.e. with the heavier elements.

Now, the two compounds (cation-exchanger and complex) helds strongly  different elements, one smaller in size and other larger in size. How will presence of two enhance separating property? Also here ammonium phosphate is mono-, di- or tribasic?

Following graphs are also given

Please explain the meaning and significance of the graphs.


texts: According to KMT, is the velocity of an ideal gas always sqrt(3RT/M)?

texts:
It is a common textbook question to treat the root mean square velocities of an ideal gas as given by the following equation:
$$v_\text{rms}=\sqrt{\frac{3RT}{M}}$$
I was wondering about the validity of this equation, particularly as it applies to gases that are not monatomic. For example, in the following question from Zumdahl et al., it says:

Calculate the root mean square velocities of $\ce{CH4}$ and $\ce{N2}$ molecules at
$\pu{273 K}$ and $\pu{546 K}$.

The answer key gives $\pu{652 m/s}$ for methane at $\pu{273 K}$, $\pu{493 m/s}$ for nitrogen at $\pu{273 K}$, $\pu{922 m/s}$ for methane at $\pu{546 K}$, and  $\pu{697 m/s}$ for nitrogen at $\pu{546 K}$. These were all calculated with the equation $$v_\text{rms}=\sqrt{\frac{3RT}{M}}$$
Why is this equation valid for all ideal gases? Shouldn't it be $$v_\text{rms}=\sqrt{\frac{6RT}{M}} \text{ for methane}$$ (because there are $3$ rotational degrees of freedom in addition to $3$ translational degrees of freedom), and
$$v_\text{rms}=\sqrt{\frac{5RT}{M}} \text{ for nitrogen}$$ (because there are $2$ rotational degrees of freedom)?
If my thoughts are not true, then why is it commonly reported that the average molar specific heat of an ideal monatomic gas (at constant volume) is $3/2RT$, that of an ideal diatomic gas is $5/2RT$, and that of a nonlinear gas is $3RT$?


texts: why HI isn't fully miscible with cold water when HF is?

texts:
HF is more soluble in water than HI , due to greater hydrogen bonding in HF , accepted
but, on the other hand HF is a very weak acid so it's dissociation will be meagre when compared to HI's dissociation , so why is HF and not HI more soluble , am I misinterpreting the concept of solubility ?


texts: Distinguishing between octahedral and tetrahedral holes

texts: I know the question sounds a bit silly and there are many similar answered questions but my 3D visualization (imagination) is very bad. There are some images of octahedral and tetrahedral holes but still there's no easy explanation. Can someone help me?


texts:
What is the colour of $\ce{C2N2NiS2}$ (Nickel thiocyanate)?

In most of the web sites it only molecular weight,formula and other specifications but its colour is missing every where.


texts: Why does the molar conductivity decrease with increasing charge density?

texts:
This is a question in a problem sheet I have been set. Is it do do with the following equation: $\Lambda=\Lambda_0-a\sqrt c$? Surely charge density is proportional to concentration so therefore molar conductivity would decrease linearly with the square root of concentration (and $c$ $\alpha$ charge density?). Also, what is the physical origin of this equation; my lecture notes simply say that the ions interact with each other, is it as simple as that?

The second part to this question asks "Does the actual conductivity decrease?". Presumably by "actual conductivity", he means $\kappa$ where $\kappa=\Lambda c$. I have no idea about this part so any help would be much appreciated.


texts: Aromatic Apparent Substituion Reaction Mechanism

texts:
The first molecule reacts with $\ce{NaOH}$ to form the second molecule. I am told that it does't undergo via a substitution mechanism. I am asked to draw the mechanism for it.

I am thinking that the double bond will attack the OH group (addition reaction) so that it will add onto the meta carbon.  Then the bromine group will leave (elimination reaction) which then the OH group attacks the para carbon.

I am not really sure if that is correct. Could someone please help me out. Thanks.


texts: Temperature at which the reaction Oxalic acid + KMnO4 becomes autocatalytic

texts:
As described many times, the reaction between oxalic acid and potassium permanganate can be autocatalytic due to the production of Manganese ions.
I've read that this only occurs at higher temperatures though, but I cannot find a procedure suggesting a range of temperatures at which to perform the experiment.


texts: Why is water considered ionic in fuel cells but otherwise covalent?

texts:
If water, $\ce{H2O}$ is a covalent compound formed by sharing of electrons, why is it said (in case of fuel cells) that formation of water from hydrogen and oxygen is a redox reaction (transfer of electrons, not sharing). This would make it an ionic compound.

Any insights?
Note that, the concept of water being formed as a result of redox reaction is highlighted in fuel cells (which is the basic principle of fuel cells - generating electricity by exploiting this transfer of electrons).

I know how fuel cells work, and it is indeed a redox reaction; but my doubt is - can water be formed by both covalent/ ionic means?  (In textbooks, or in exams when asked to identify bonding present in water); when both covalent and ionic type can be achieved in its formation? Is both "covalent" and "ionic" correct while describing the formation of $\ce{H2O}$ molecule?


texts: Diagonal line going through groups IIIA-VIA on the periodic table

texts:
Why is there a diagonal line cutting through some of the nonmetals and metalloids on the periodic table in groups IIIA, IVA, VA, VIA, and VIIA?

Is there any historical background about it?


texts:
$$\ce{FeO}$$

Is called "Iron(II) oxide ".

$$\ce{Fe_2O_3}$$

Is called "Iron(III) oxide ".

The number in the parenthesis is "Valence" of the substance. Frankly, I don't know how to calculate such number. Can you explain to me, with this example, how come $\ce{FeO}$ has valence $2$ and the other one has valence $3$?

The only thing I know how to do is calculate the electron configurations of each element.

For Iron, it is $1s^22s^22p^63s^23p^64s^23d^6$.

For Oxygen, it is $1s^22s^22p^4$.

I am told that based on the electron configuration you can get the valence of each element. And then, you can calculate the valence of $\ce{FeO}$ and $\ce{Fe_2O_3}$. But how?

I made a question before Calculating valence of oxides, but it was wrongly formulated (they corrected me on the definition of Valence, but turns out what I actually need was how to calculate it), so I'm flagging it to be closed.

Edit The question How to get the valencies of elements? doesn't explain how to calculate the valence of a combination of two elements.


texts: Why does meta directing group also pull electrons from ortho and para positions?

texts: I have been taught that electron withdrawing groups are meta directing. If it cannot modulate electron density over ortho and para positions during resonance, why does it help in nucleophilic substitution in a aromatic ring in which the leaving group is situated at ortho/para positions?


texts: Why is contact angle higher when I let the glass to be dried in silan solution?

texts:
I've read in literature that the silanization reaction is completed in a second. However, I realized an interesting thing; after one hour that my cleaned glass beads are deep coated in a silan bottle two things might happen:

1) If I take out the beads from the silan bottle and then wash them with water and then acetone, contact angle is ~102 deg and the beads are still transparent.

2) But if I take out the beads and then put them on a flat surface (in one layer) and pour some silan solution on them and let them to be dried in silan, then the contact angle is ~118 deg and glass beads are not transparent anymore (they're milky white).

Has anybody had a similar experience or know the reason of this?


texts: Could anyone explain why the adsorption tanks are being fed twice, with one input from the top of the tank (Strong and weak slurry), while also another input from the bottom (Fresh Carbon). Why does the tank process slurry (top) and adds carbon through the bottom?


texts: How does one test for lead in dry paint?

texts:
What analytical methodologies are capable of identifying lead in peeling paint? I am a hobby chemist owner of a Clinical Research Investigative Site.  Please tell me if this site is only for professional chemists.
If so, I will cancel my registration.


texts: What is the net ionic equation of the following?

texts:
Aqueous chlorine is added to a solution of aluminum bromide in a single replacement reaction which forms no precipitate and bromine liquid. Determine the net ionic equation.

Since this is a single replacement reaction, it will take the form of  $$\ce{A + B-C -> A-C + B}$$

Since this reaction forms no precipitate, the new compound will not be a solid.

$$\begin{multline}
\ce{aqueous chlorine + solution of aluminum bromide ->}\\
\ce{ non-solid compound + liquid bromine}
\end{multline}$$
\begin{align}
\ce{Cl2(aq) + Al^{3+}Br3^-(aq) &-> \text{non-solid compound} + Br2(l)}\\
\ce{Cl2(aq) + AlBr3(aq) &-> \text{non-solid compound} + Br2(l)}\\
\ce{Cl2(aq) + AlBr3(aq) &-> Al^{3+}Cl3- + Br2(l)}\\
\ce{Cl2(aq) + AlBr3(aq) &-> AlCl3 + Br2(l)}
\end{align}

Since most chloride salts are soluble (except for silver halides), $\ce{AlCl3}$ is predicted to be aqueous.

\begin{align}
\ce{Cl2(aq) + AlBr3(aq) &-> AlCl3(aq) + Br2(l)}\\
\ce{3Cl2(aq) + 2AlBr3(aq) &-> 2AlCl3(aq) + 3Br2(l)}
\end{align}

Here is the complete ionic equation:

$$\ce{6Cl⁻(aq) + 2Al^{3+}(aq) + 6Br-(aq) -> 2Al^{3+}(aq) + 6Cl-(aq) + 3Br2(l)}$$

Cancelling out the spectator ions, we get

$$\ce{6Br-(aq) -> 3Br2(l)}$$

In lowest terms:

$$\ce{2Br-(aq) -> Br2(l)}$$


texts: Why does calcium carbonate decompose in sulphuric acid?

texts:
Here's the reaction:

$\ce{H2SO4(aq) +  CaCO3(s)  ->   CaSO4(s)  + H2O(l)  +   CO2(g)}$

I don't understand why calcium carbonate decomposes in sulphuric acid. It's not soluble in water. I could understand the hydrogen ions oxidizing the calcium, yet the reaction isn't a redox reaction; the oxidation states remain the same!


texts:
I have been asked to identify suitable reagents for the following transformation:

(Apologies it's back to front - the question is a map of reactions and I took a snapshot).

I really have no idea about this one. Don't even know where to begin, sorry. For the purposes of the question I only need reagents but I would appreciate a mechanism if you know it. Thanks.


texts: Why is disilyne $\ce{Si2H2}$ bent when the steric number of silicon is 2?


texts: Finding out the concentration of oxygen in water

texts:
I read in a biology course that you can determine the concentration of oxygen in water by adding some $\ce{NaOH}$ and then a small amount of $\ce{MgCl2}$. They say that a dark coloured precipitate is formed.
I can't see a way of writing this reaction. Can anyone help me?


texts: Why are there no edge dislocations in a face-centered cubic (FCC) lattice?

texts:
In crystallography, we know that the Burgers vector is parallel to the dislocation direction in a screw dislocation, and perpendicular in a edge dislocation.

Furthermore, I have in my lecture notes "FCC cannot have edge dislocations" but there is no explanation of why, aside from "in FCC, the Burger's vector belongs to the family of the dislocation direction vectors"

I don't understand what this means.


texts: Safe chemical reactions to start a campfire

texts:
I'm looking for a way to start a small fire electronically with widely available chemicals. It would be great if they are safe to use with metals (not necessarily). But the biggest requirement is that it should be SAFE at medium scales and should not make an explosion.
I have found out $\ce{H2SO4 + KMnO4}$ can start a fire. But is it possible to do it with diluted H2SO4 because concentrated is not safe to handle?
NB: I only want a small ignition. The rest can be continued with some fuel, I believe.
Also, I doesn't possibly need to be a chemical reaction. Anything that can trigger a safe fire is enough


texts: What is the scaling for % completion time in a Michaelis–Menten scenario as a function of substrate concentration?

texts:
Say I have a straightforward Michaelis-Menten reaction where an enzyme $E$ at some fixed concentration $[E]$ forms an interaction complex $ES$ with a substrate $S$ (with initial concentration $[S]_0$), and at a rate $k_{cat}$ can irreversibly convert the substrate $S$ to a product $P$.  The rate of interaction complex formation $ES$ is $k_f$ and its dissociation rate is $k_r$, such that overall, we have the reaction:

$E + S \rightleftharpoons^{k_f}_{k_r} ES \to_{k_{cat}} E + P$

Is there an explicit expression for the time $\tau_{v}$ to convert some percentage $v$ of the substrate $S$ to product $P$?  In lieu of an explicit expression for $\tau_{v}$, what scaling for this time should we expect for $\tau_{v}$ as a function $[S]$ (holding $[E]$ fixed)?

Ultimately, for $\tau_{v} \approx 1$ I suppose the steady-state approximation will begin to fail?


texts:
I need to make a cloudy white liquid where the particles won't eventually settle out. It will be exhibiting the Tyndall effect for a very long time.

I'd use milk, but I don't want it to become rancid. I've tried white inks and fabric softener, but both eventually tend toward the bottom half of the container. I think it's a matter of particle size.

What substance would hit the sweet spot - small enough to stay dispersed, large enough to scatter light, and not reactive?


texts: Why does the nitrile carbon experience more shielding than a carbonyl carbon in CNMR?

texts:
In organic chemistry lecture, we were given a chart of approximate signal shift ranges for different carbon types in CNMR spectra. carbonyl carbons (C=O) have a range of about 155-210 ppm, but the nitrile group (C≡N) has a signal range of about 110-140 ppm. I understand that oxygen is a more electronegative atom, so it might pull electron density away from the bonded carbon (deshielding), but the C≡N is a more polar bond, which means the electron density spends a lot of time around nitrogen in this bond. Doesn't this imply the C≡N carbon would produce a signal more downfield than that of the C=O carbon?

From the given data ranges, it seems the opposite is true and the carbon of nitrile is more shielded despite the bond polarity.


texts: Why is it that energy of electrons in higher orbits is greater than the ones in lower orbits?

texts:
There is this picture I found online which indicates that the energy level is higher as we go up and more electrons are added to the atom.

What I'm having trouble understanding is why the energy level is higher and not lower. The electrons are further and further away from the nucleus, at infinity their energy would be zero. Is it correct to say that the electrons' energy is negative and as we go further it increases, going to zero at infinity?

That is the only way I can see all this make sense.


texts: What are good books about MO theory that don't require a lot of math background?

texts: Are there any books about MO theory that explain the theory to a certain detail but don't rely on a lot of math background or explain the math within the book?


texts: Find the structural compound from carbon and proton NMR spectrum

texts:
The proton and carbon NMR spectrum datas for compound W (201 g/mol) are
shown below. Based on Diagram 1 and Diagram 2, draw the structural formula of compound W according to the type of hydrogen and carbon.

I have extracted the information from the NMR spectrum into a table.


texts: Does anyone have information about Piquet and Calitet (chemists)?

texts:
I was given a set of names of chemists to research and one of them was actually a duo that I understand to have been French chemists (at least their last names suggest it). I have queried and queried not simply Google, but also academic databases (Wiley, ProQuest, Elsevier, etc.), yet I've found nothing.

I believe I am spelling the names correctly, but for clarity, phonetic expression of their surnames is:

  "PEA-ket and CAL-ee-TET"

Hath anyone information on these names within chemistry (or similar natural science discipline)? It would allow me to end a nearly two month search – one way or another.

Most appreciative for any corrections if I have erred in spelling, nation of origin, etc.


texts: Why is it impossible to liquefy a gas with only pressure?

texts: Why is it impossible to turn it to liquid by using only pressure after it reaches critical temperature? What happens in the molecular level? If we put enough pressure, the molecules are supposed to come close enough to become liquid. Then why it is impossible?


texts: What is the Natural abundance of Potassium

texts:
The three naturally occurring isotopes of potassium are $\ce{^39K}$ ($38.963707\:\mathrm{amu}$); $\ce{^40K}$ ($39.963999\:\mathrm{amu}$); and $\ce{^41K}$.

  The percent natural abundances of $\ce{^39K}$ and $\ce{^41K}$ are $93.2581\%$ and $6.7302\%$ respectively.

  a) What is the natural abundance of $\ce{^40K}$?

  b) Determine the isotopic mass of $\ce{^41K}$.

So I started to utilize this equation:

$\mathrm{atomic\:mass = (fractional\:abundance\:isotope\:1
\cdot mass) + (fractional\:abundance\:isotope\:2 \cdot mass)}$

But then I realized that I did not have some values. $\ce{^39K}$ is the only isotope which has two values. $\ce{^40K}$ only has the mass weight, however, if I were to multiply $\ce{^40K}$'s mass with ($1-0.932581$) would that help me arrive at an answer?

Also, would that answer be accurate since it only takes into account that there are only to values that add up to 100%.


texts: How can I rationalise the different basicities of cyclohexylamine, piperidine and morpholine?

texts:
Compare the basicity of the following compounds:

Comparing compounds I and II
Since there is no conjugated system, there is no resonance at play and we only have to discuss hyperconjucation and inductive effect.
The conjugate acid of compound I has one α-hydrogen while the conjugate acid of  compound II has four α-hydrogens. So, according to hyperconjugation, the conjugate acid of compound II is more stable than the conjugate acid of compound I and hence the basicity of compound II is more than that of compound I.
Further, the conjugate acid of compound I has one α-carbon, two β-carbons, two γ-carbons and one δ-carbon. While the conjugate acid of compound II has two α-carbons, two β-carbons and one γ-carbon.
Alkyl groups are electron releasing groups and, since the conjugate acid of compound II has its carbon atoms closer to the amine than in the case of compound I, it is further stabilised, and hence compound II is more basic.
Comparing compounds II and III
The conjugate acid of compound III has an ether group attached to the amine while that of compound II has an alkyl group to the amine. Since ether is an electron withdrawing group and alkyl is an electron releasing group, the former will destabilise the conjugate acid compound III while the latter will stabilise the compound II, and hence compound II is more basic than compound III.
So, I know that compound II is the most basic, but I still don't know how to compare compounds I and III.
Can anyone help?


texts: Is it possible and safe to use liquid nitrogen to quickly cool a 5 gallon tank of liquid from room teperature to say 34 °F? Or is there another way that can produce really fast results?


texts: Method to know the number of isomers of metal complexes

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Whenever I try to find the number of geometrical isomers (including optical isomers) of coordination compound, I got confused, and mostly miss few isomers. Is there any standard method to know the number of isomers of compounds such as $\ce{Ma2b2c2}$ or $\ce{[M(A-A)a2b2]}$.

where $\ce{M}$ is metal and $\ce{a,b}$ are monodentate ligands while $\ce{A-A}$ is a bidentate ligand.


texts: The pentagonal pyramidal structure of XeOF5-

texts: Why does the $\ce{XeF6}$ molecule have an octahedral structure while $\ce{XeOF5-}$ has a pentagonal pyramidal structure, despite both molecules having 7 electron pairs? I suppose the extra electron on oxygen would distort the molecule somewhat, but this seems like an extreme outcome.


texts: Are there any significant industrial processes that use liquid ammonia as a solvent?

texts:
There are some interesting laboratory reactions that use liquid ammonia as a solvent (for example, the Birch Reduction where an alkali metal is dissolved in liquid ammonia).

There have also been some high volume industrial processes that use liquid ammonia as a solvent (the weedkiller paraquat has two, quite different, production routes using liquid ammonia producing thousands of tonnes a year). One uses dissolving sodium (like the Birch reduction):

But are there any other significant chemical manufacturing processes that use it?

NB I would include the production of pharmaceuticals or their ingredients as well as any bulk chemicals.


texts: Cheap and not messy solvent for motor oil

texts:
I have an old oil cooler of  an old Volkswagen engine (the type where the oil itself is cooled, and uses no water) stained with decades of usage. If I pass water through it, it comes out clear, but if I pass a clear oil through it, it comes out black.

What is the best method to clean it that uses cheap and easy to find substances? I want to use it to cool clean mineral oil, I want my oil to remain clean.

My father suggested to pass mineral oil through it until what comes out is clean, then install it in the system, but that would be horribly expensive and messy, and I would need to discard all that dirty oil properly afterwards. I myself thought of using gasoline, filling halfways, shakink and discarding, until clean enough, but although that would be less expensive, it would be as messy as the first option, and probably dangerous. My sister suggested using water and kitchen wash-up liquid. That would be much less messier, because it is water soluble, but I don know the proportion of water and kitchen detergent tI must use for it to be effective. My last idea was to use some grese remover like Ajax, that would not be so.much messy, either.

So, what do you suggest?


texts: What is the reason of explosion of batteries?

texts: In social sites we see many pictures showing awareness of not using smartphone while charging because of the reason that battery explode while charging, is really batteries explode and if yes than what is the reason behind it.


texts:
IUPAC defines a monomer as,

  A molecule which can undergo polymerisation thereby contributing constitutional units to the essential structure of a macromolecule.

Bearing this in mind, I thought about molecules which exhibit hydrogen bonding. Take water for example: one water molecule bonds to another, and that one bonds to another, and another, etc. In the end, you'll have a long chain of water molecules bonded together. This process of water molecules coming together and hydrogen bonding sounds like they 'polymerise' in some way.

To explain my point, consider an infinite amount of water. Here, I'd imagine there to be an infinitely long chain of water molecules bonded together. This sounds like usual polymers I see, where there's an infinitely long chain of repeat units. However, the polymerisation is different for those.

Hence, I have two questions: could a single water molecule be described as a monomer? And, could a long chain of bonded water molecules be described as a polymer?

P.S. This doesn't just have to apply to water. The same could be said about a single alcohol molecule/a long chain of bonded alcohol molecules.


texts: Acid catalyst choice on reaction of carbonyl group and O/N nucleophiles

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For oxygen nucleophiles, e.g. $\ce{ROH}$, when reacting with a carbonyl group to form acetal, the acid catalyst used is protonated alcohol.
for nitrogen nucleophiles, e.g. $\ce{RNH2/RR'NH}$, when reacting with a carbonyl group to form imine/enamine, the acid catalyst used is $\ce{NH4+}$ instead of protonated alcohol.
According to both reaction mechanisms, both catalysts are just acting as $\ce{H+}$ donators & acceptors, so why 2 different acid catalysts need to be used? Can't I use protonated alcohol all the time?


texts: Why is the molecular dipole the main determinant of whether a substance dissolves in another substance?

texts: Consider a covalent molecule such as carbon tetrafluoride. In $\ce{CF4}$, each $\ce{C-F}$ bond is polar covalent. However, this substance is considered overall non-polar because each bond dipole moment cancels out each other, resulting in a negligible molecular dipole moment. This explains why it is non-polar. But how can that be the case? Certainly, such a substance with such strong bond dipoles would have some sort of strong interaction with polar solvents? Why do we not take the individual bond dipole moments into consideration?


texts: Where does the extra electron come from in the Lewis Dot Electron structure of say for example nitrate ion?

texts:
As most of you know, this is the diagram for nitrate ion:

To draw this, i have to make all bonds with electrons from nitrogen, nitrogen only has five valence electron so ONE of the bonds consists of one electron from nitrogen and the other from the MYSTERIOUS electron, that comes out of no where.

My book tells me that's if simply how you draw Lewis diagram for N, O, F, Cl. When the oxidation is positive, take away electron and when it is negative, add.

In any covalent compound, bonding atoms share their electron to complete octet.( yeh, there are exceptions)

In this case, N and O share their electron. But when I count the number of valence electrons, a negative charge means a extra valence electron. NOW, where does this extra valence electron come from?


texts: Does the crystallinity of seed crystals affect the final crystal structure? and is it different depending on the crystallized material?