texts: Is there a model for (quality of) two-component-polymerization (dependent on e.g. concentration)?

texts:
Sadly my chemistry background is only from high school (I'm a roboticist), but I try my best to explain the problem:

Situation: Lets say I have two water based solutions/suspensions. One contains cells with A-hooks and one contains proteins with B-hooks. Now i mix those two liquids and then the As will attach to the Bs. And so they will form sort of a polymer (not sure if this is the right phrase here)

Question: Now is there a model that tells me how "well" the polymerization works, dependent on the concentration of the two solutions, temperature, affinity of A to B, whatever other parameters there might be. I think a good measure for "good polymerization" would be the distribution of lengths of the chains or connectivity or some other graph metric.

The Background is the idea to build a 3D tissue printer without support structures. A and B refers to Biotin and Streptavidin

Clarifications:

each cell will have several 100 A-hooks, the proteins can be engineered to have an arbitrary number of B-hooks (we would like to optimize that)
to make it work we obviously need to connect each cell with as many different individual proteins as possible and vice versa.


texts: Reaction mechanisms for organohalides from alcohols

texts:
For the syntheses of organohalides from alcohols, what would plausible reaction mechanisms be for the three following reactions?

$$
\ce{R-OH + NaBr + H2SO4 -> R-Br + NaHSO4 + H2O}
$$

$$
\ce{R-OH + PCl5 -> R-Cl + POCl3 + HCl}
$$

$$
\ce{R-OH ->[red P][Br2 or I2] R-X}
$$


texts: Why can UV light initiate a reaction between hydrogen and chlorine gas?

texts:
Can someone explain me how does UV light help combine chloride gas and hydrogen to produce hydrochloric acid?

$$\ce{Cl2(g) + H2(g) -> 2HCl(g)}$$


texts:
I do a lot of short term ocean field deployments where system electronics are self contained in a submersible enclosure. A new project I'm working on requires a long term deployment in the deep ocean. Therefore, once the enclosure is deployed, I can not just go recover the instrument if something fails. I've spoken to a lot of colleagues about how they prepare electronic enclosures and one of the standard protocols is purging the enclosure of atmospheric air. For one, any moisture in the air can condense at cold, deep depths, which can cause electrical problems. I think another reason they do it is to reduce oxygen exposure. Typically the purging is done with argon from an air cylinder. However, this is something I don't have. Now I know I can go out and get one...that's not the point of this question. What I do have is a small nitrogen generator that was needed for other projects.
The question I would like to ask here is, can I use the 99.x% dry nitrogen air from the nitrogen generator as a substitute for argon? I know argon is denser than nitrogen, so clearly is a better choice, but I'm not concerned with the better choice. I want to know if I can use what I have at my disposal to achieve the same goal: replace atmospheric air with 99.x% dry nitrogen air?


texts:
I know that crown ethers have the interesting property of strongly complexing alkali metals, which allows them to be used in organic solvents (eg. as "dissolving-activity enhancing agents" for potassium permanganate or potassium tert-butylate).

Having never used such molecules myself, I was wondering: is there a procedure employed in order to remove the complexed metal, hence allowing a recycling of that ether?

I am sorry if the question might be trivial, but I couldn't find an aswer online.


texts: Mathematical properties of free Gibbs energy

texts:
I'm wandering, if some mathematical properties of the free Gibbs energy (also called thermodynamic potential) are well known.
For instance in chemistry, if $n_i^\alpha$ denotes the number of moles of species $i$ in phase $\alpha$ and G is the free Gibbs energy.
I know that G must be an homogeneous function of degree one in $n_i^\alpha$.

Do we have more information like continuity or coercivity properties of G ?


texts: What can we say about the dipole moment of terephthalic acid?

texts:
The dipole moment of quinol is not zero because it can exist in two different energetically favourable conformations. The weighted average is calculated to arrive a dipole moment of 1.6 D.

According to Wikipedia, the dipole moment of terephthalic acid is zero.
But few sources have a different opinion.

Can we say that terephthalic acid can also exist in these two conformations, leading to a high dipole moment?


texts: Dominant contribution of v = 0 → v = 1 transition in vibrational spectroscopy

texts:
Recently I had studied vibrational spectroscopy using the quantum harmonic oscillator model.

After stating the gross selection rule [that vibrational oscillation demands a change in dipole moment for polar molecule] and showing that transitions are possible only between adjacent energy states ($\Delta v = \pm 1$), my professor's notes state that:

  Most of the molecules will populate the lowest energy states, following Maxwell–Boltzmann distribution, the dominant contribution to IR absorption spectra comes from $v = 0 \to v = 1$ transition and is called fundamental transition.

I do not understand the point that 'Most of the molecules will populate the lowest energy states...'. What does it mean and how does it lead to the conclusion that most of the times a transition of $v = 0 \to v = 1$ will take place?


texts:
There is the .csv file with a large amount of descriptors and known experimental activity.

Which software can find and describe model for prediction. Most important - numerical representation of model - which descriptor is taken with coefficients.

I am looking for any software, not necessary free.


texts: expression of apparent reaction quotient

texts:
question
When computing the Gibbs energy change of a reaction using Legendre-transformed $\Delta_fG'$ values for a given $\mathrm{pH}$, the formula of the $\Delta_rG'$ of the reaction is:

$\Delta_rG' = \Delta_rG'^\circ + RT \ln Q'$

How should $Q'$ be expressed in practice? Should it include $\ce{H^+}$? Based on the reasoning below, I think it shouldn't, but I would like to have confirmation.
example
Lets consider the following reaction;

$\ce{A^- + H^+ <=> AH}$

In conditions of constant temperature and pressure, the Gibbs energy change of the reaction can be formulated as

$dG_{T,P} = \mu_{\ce{A^-}} dn_{\ce{A^-}} + \mu_{\ce{H^+}} dn_{H^+} + \mu_{\ce{AH}} dn_{\ce{AH}}$

If we suppose that the reaction occurs in a buffered medium such that the activity of $\ce{H^+}$ is constant through the advancement of the reaction, a correct way to represent the system is as an open system exchanging $\{\ce{H^+}\}$ with its surrounding (c.f., Ref.1):

$dG_{T,P} = \mu_{\ce{A^-}sys} dn_{\ce{A^-}sys} + \mu_{\ce{H^+}sys} dn_{\ce{H^+}sys} + \mu_{\ce{AH}sys} dn_{\ce{AH}sys} + \mu_{\ce{H^+}buf} dn_{\ce{H^+}buf}$

where $sys$ denote the chemical system and $buf$ the buffer, which acts as the "surrounding" in the sense of the 2nd law of thermodynamics.
A commonly used way to enforce constant $\mathrm{pH}$ in this system is to apply a Legendre transform on $dG$ such that

$dG'_{T,P} = dG_{T,P} - d(n_{\ce{H^+}sys} \mu_{\ce{H^+}sys}) = \mu_{\ce{A^-}sys} dn_{\ce{A^-}sys} + \mu_{\ce{AH}sys} dn_{\ce{AH}sys} + \mu_{\ce{H^+}buf} dn_{\ce{H^+}buf} - n_{\ce{H^+}sys} d\mu_{\ce{H^+}sys}$

since $\mathrm{pH}$ is constant, $d\mu_{\ce{H^+}sys} = 0$ so

$dG'_{T,P,\mathrm{pH}} = \mu_{\ce{A^-}sys} dn_{\ce{A^-}sys} + \mu_{\ce{AH}sys} dn_{\ce{AH}sys} + \mu_{\ce{H^+}buf} dn_{\ce{H^+}buf}$

We can develop this formula by expressing $\mu_i = \mu_i^\circ + RT \nu_i \ln \frac{\{i\}}{c^\circ}$, with $\nu_i$ being the stoichiometric coefficient for chemical species $i$, $\{i\}$ being its activity and $c^\circ$ being its reference activity in standard state (i.e. $1$) to get to this familiar expression:

$dG'_{T,P,\mathrm{pH}} = \Delta_r \mu^\circ + RT \ln \frac{\{\ce{AH}\}}{\{\ce{A^-}\}} + RT \ln \frac{\{\ce{H^+}buf\}}{c^\circ}$

$RT \ln \frac{\{\ce{H^+}buf\}}{c^\circ}$ being constant, what is called $\Delta_r G'^\circ$ should be $\Delta_r \mu^\circ + RT \ln \frac{\{\ce{H^+}buf\}}{c^\circ}$, which means $Q' = \frac{\{\ce{AH}\}}{\{\ce{A^-}\}}$. The contribution of $\ce{H^+}$ is then not present in $Q'$ as it is in $\Delta_r G'^\circ$ already. Is that right?

Reference:

Lionel M. Raff, William R. Cannon, "On the Reunification of Chemical and Biochemical Thermodynamics: A Simple Example for Classroom Use," Journal of Chemical Education 2019, 92(2), 274–284 (https://doi.org/10.1021/acs.jchemed.8b00795).


texts: What did I do wrong in my temperature change calculations?

texts:
I am doing an online assignment where I am being asked to find temperature change but there is something wrong in my calculations as I am getting the answer wrong. Can someone help me figure out where I went wrong in my calculations?
Assignment Instructions:
Solve for the unknown variable using the specific heat formula. Input your answer (without units) and using the correct number of sig figs.
Question:
If 31,500J of heat is used to warm 750g of water, what is the temperature change?  The specific heat of water is 4.184J/goC.
My Answer: 10
Since I am being asked to find the change in temperature in this question, I split the original equation up. First, I did (750) * (4.184) and got 3138. Then, I did (31,500) / (3138) and got 10.0382409178. The lowest number of significant figures is two, so I rounded 10.0382409178 to 10. Why is the computer counting my question as wrong?
I used the equation temperature change = (heat) / (mass) * (specific heat). The variables I used are q (heat), m (mass), and c (specific heat).


texts:
Is there some kind of database that has information about phase diagrams of different substances? I'm mostly looking for phase diagrams of elements (silicon, iron, hydrogen, etc.) because I'm trying to write a planetary generator, but I cannot find any information about the mathematics of a phase diagram.

Better yet, is there some way to simply approximate the phase diagrams of different compounds? I'm looking for simulation complexity and variation more than I want realism.


texts: Is the chemical structure of an amide bond (-CONH) or (-CONH2)?

texts:
The Dictionary definition of an amide is

  an organic compound obtained by replacing the −OH group in acids by the −NH 2 group.

So from this, I deduced that the bond would be CONH2.

But when I searched around, I found some images that showed the bond only had one hydrogen atom, like so:

Which is the correct bond structure? I'm looking specifically at the condensation polymerization of diamine and diacarboxylic acid to form nylon.

And also, I see online that lots of bond structures (like NH2 and COOH) are prefixed with a dash, so they'd appear like -NH2 and -COOH. Is this just a personal preference, or is there a more elaborate reason behind this?

I'm currently doing the GCSEs.

Thanks


texts: Trend in ionisation potential in period 2

texts:
Carbon has valence electronic configuration of $2s^2$ $2p^2$. Beryllium has configuration $2s^2$.So carbon should have less ionisation potential than Beryllium as it is easier to remove electrons from $2p$ subshell than fully filled $2s$ subshell.

But I found that in JD Lee it is mentioned that carbon has more I.P. than beryllium. How can it be explained?


texts: What is the explanation of the odd even effect in liquid crystals?

texts: What is the most accepted theory for explaining the odd even effect in liquid crystals? Can anyone explain and refer the corresponding paper?


texts:
I premise, I’m a physicist and I’m working on a transfer procedure for graphene via CVD, which involves the use of PMMA as a resist layer. Studying this polymer, I still haven’t found what is the cross-link temperature (or window of temperatures) for it. Can someone give me a hand? or just a good reference?

UPDATE
Ok, maybe I’ve been misunderstood. My PMMA is diluted in anisole, and I apply it as a photoresist over the graphene sheet via spin coating. After this deposition NO Initiator is used, but it came across various heat treatment, depending in the recipe I use. My question is: does anybody know at what temperature the PMMA starts to seriously crosslink? or better: if I do more heat treatments, all at temperatures above 150 °C, am I going to have an highly crosslinked PMMA, so that a removal process in acetone solvent is impossible because it can’t get into the chains to districate them?


texts: Why can the acidic strength between H2S and HCl be explained on the basis of electronegativity but H2S and H2O can't?

texts:
Consider simply aqueous solutions of $\ce{H2S}$  and $\ce{HCl}$ . It is pretty much known that $\ce{HCl}$ is stronger than $\ce{H2S}$ in water. The reason behind that first is the electronegativity of $\ce{Cl}$ is higher than $\ce{S}$, so, in a polar medium, it becomes easier for the $\ce{H-Cl}$ bond to break than the other one.  More ever , $\ce{Cl^-}$ ion being smaller in size is extensively hydrated in water than $\ce{HS^-}$ ion, which also favours in the increased acidity of $\ce{HCl}$.

But now consider acidity of $\ce{H2S}$ and $\ce{H2O}$ in water. If we apply the similar reasons as before, we will ultimately conclude water is  a stronger acid than $\ce{H2S}$. But actually it’s the reverse. The only fact supporting the actual phenomenon is the weaker bond energy of $\ce{H-S}$, but if we apply this to the earlier case of $\ce{HCl}$ and $\ce{H2S}$, it will again contradict the actual phenomenon.

Why is this the case ? If my reasoning is incorrect, what is the actual reasoning that will support the correct acidity in both the cases ?


texts: Conservation equation in an enzyme-catalysed reaction

texts:
Consider the reaction scheme:

$$\ce{S + E ->[k_1] C1} \qquad \ce{C1 ->[k_2] E + P} \qquad \ce{S + C1 <=>[k_3][k_4] C2}$$

where $\ce{S}$ is the substrate, $\ce{E}$ is the enzyme, $\ce{P}$ is the product, $\ce{C1}$ and $\ce{C2}$ are enzyme-substrate complexes. Let $[\ce{S}] = s$, $[\ce{E}] = e$, $[\ce{C1}] = c_1$, $[\ce{C2}] = c_2$ and $[\ce{P}] = p$ be the concentrations of each respective chemical. I have used the law of mass reaction to convert this reaction into a system of differential equations:

\begin{align}
\frac{\mathrm{d}s}{\mathrm{d}t} &= -k_1se-k_3sc_1+k_4c_2\\
\frac{\mathrm{d}e}{\mathrm{d}t} &= -k_1se+k_2c_1\\
\frac{\mathrm{d}c_1}{\mathrm{d}t} &= k_1se-k_2c_1-k_3sc_1+k_4c_2\\
\frac{\mathrm{d}c_2}{\mathrm{d}t} &= k_3sc_1-k_4c_2\\
\frac{\mathrm{d}p}{\mathrm{d}t} &= k_2c_1
\end{align}

I am asked to find a conservation equation and use it to simplify this system however I haven't been taught as to what a conservation equation is. Can anyone push me in the correct direction? (and check the above differential equations are correct).


texts: Strength of hydrogen bonding in phenol or methanol

texts:
I wanted to know whether hydrogen bonding is stronger in phenol or methanol.
I saw on Wikipedia about the enthalpies of hydrogen bonding in various cases.
but could not find the answer to this question of mine.

I also want to know whether the hydrogen bond strength depends upon the carbon atom to which oxygen is attached.


texts:
Synopsis
We are given a proposed mechanism for the condensation of $\ce{(CH_3)_2CO}$ as follows
First Step: $$\ce{(CH_3)_2CO + OH^- <=> CH_3C(O)CH_2^- + H_2O}$$
Second Step: $$\ce{CH_3C(O)CH_2^- + (CH_3)_2CO -> Product}$$
Attempt and Question
I assume $\ce{CH_3C(O)CH_2^-}$ is in steady-state, and obtain subsequently that $$ k_1 \ce{[(CH_3)_2CO][OH^-]} = k_{-1}\ce{[CH_3C(O)CH_2^-][H_2O]} + k_2[\ce{CH_3C(O)CH_2^-][(CH_3)_2CO]}$$ since I'm assuming the rate of change of $\ce{[CH_3C(O)CH_2^-]}$ is $0$.
From here, in my original attempt, I factored out the $\ce{[CH_3C(O)CH_2^-]}$, solved for it, and plugged it in to my rate equation $$\ce{Rate = $k_2$ [CH_3C(O)CH_2^-][(CH_3)_2CO]}$$ to obtain $$\ce{Rate = \frac{$k_1k_2$ [(CH_3)_2CO]^2[OH^-]}{$k_{-1}$[H_2O] + $k_2$[(CH_3)_2CO]}}.$$ But looking at my solution, I realize I didn't eliminate the $\ce{H_2O}$ term. This is where my question lies. In the steady state approximation, do I assume $\ce{H_2O}$ is in steady state too and follow the same steps, substituting it into my equation for the concentration of $\ce{CH_3C(O)CH_2^-}$? I tried that, but in doing so, I obtain $$\ce{$k_1$[(CH_3)_2CO][OH] = $k_{-1}$[CH_3C(O)CH_2^-][H_2O]}$$ and that $$\ce{[H_2O] = \frac{$k_1$[(CH_3)_2CO][OH^-]}{$k_{-1}$[CH_3C(O)CH_2^-]}}.$$Plugging that in to my equation for $\ce{CH_3C(O)CH_2^-}$, I obtain something that seems absurd, mainly that $$k_1 \ce{[(CH_3)_2CO][OH^-]} = \ce{$k_1$[(CH_3)_2CO][OH^-]} + k_2[\ce{CH_3C(O)CH_2^-][(CH_3)_2CO]}.$$ This, being obviously wrong, led to great confusion. How do I deal with the $\ce{H_2O}$ term? I recognize it has no role in forming the products, but it does have a role in the rate of disappearance of $\ce{CH_3C(O)CH_2^-}$, so I can't just throw it away right? If I can, why is that? What am I missing here? This is my first chemistry course in college, so if this is a stupid question or if it's already been asked, please just kindly point me to a helpful resource.


texts: Finding cubic ice CIF files in crystal database

texts:
Could anyone please tell me where I could find the the structure of cubic ice (ice Ic) as a CIF file?

I have been searching the cambridge structural database using "H2O", "water", "dihyrogen oxide" and "ice" as search key words, but cannot find anything!


texts:
In Dow's process of manufacture of phenol, $\ce{PhCl}$ is fused with $\ce{NaOH}$ at high temperature and pressure. What are the possible side products? And what is the intermediate formed?

I think the intermediate will be benzyne. After the formation of benzyne, $\ce{OH-}$ nucleophilic attack takes place. the reaction mixture also contains some phenoxide ions. So Diphenyl ether is a possible side product (Formed by nucleophilic attack of $\ce{PhO-}$). But the answer given species two side products: Diphenyl ether and p-phenyl phenol. How can I explain the second product?


texts: What is meant by the "probability density" of finding an electron?

texts: Could someone please explain to me in layman's terms what probability density of finding an electron means, just as probability means chances of finding an electron. With due respect, please don't answer the formula or the distribution curves as I understand and can plot those, I just need the definition.


texts: Would Z and E isomers show different optical activity?

texts: Consider this compound, which is in E-configuration and that red asterisk denotes the chiral carbon. If I were to somehow cause the E-configuration of the alkene part to Z-configuration keeping the rest of the molecule same, would it have the same optical rotation?


texts: What are the concentration changes when diluting an equimolar acetic acid: acetate buffer?

texts:
When a buffer (for example, a mixture of 100 mM acetic acid and 100 mM acetate), is diluted 10-fold, all the concentrations change drastically. Surprisingly, after re-establishment of equilibrium, the pH is not much different from the starting pH.

How can you visualize how diluting a buffer disturbs the equilibrium of a buffer  and how the system returns to equilibrium? To make things simple in a thought experiment, we will posit that dilution is faster than acid/base chemistry, i.e. the first step is dilution without any reactions, and the second step is acid base chemistry without further dilution.

The explanation/visualization could be at the molecular or bulk level, and could use kinetic or K vs. Q or Gibbs free energy arguments.


texts: What reaction is expectable from the atomized reactants?

texts:
Let we have a reaction that starts from some reactants to produce some products. When the activation energy is provided to the reactants they will be atomized and produce a gas of individual atoms. The gas contain the whole atoms that can either form again the reactants, or form the products, or instead form the elemental molecules of themselves from which the reactants or products can be produced in other reactions. Now that the gas of all individual atoms is common for all these different reactions my question is what conditions decide which reaction to happen?

Can I say the reaction happens in the direction at which the Gibbs free enthalpy decreases more rapidly? Or do thermodynamic conditions like temperature, pressure and especially concentration of the species also play a role, independent of the variation in the Gibbs function?


texts: How can you use indicator titration to determine the pH of a complex solution like ocean water if at all

texts: Could you measure the pH of ocean water by using a strong acid-weak base titration? I was thinking that you could set up a standard titration with ocean water as the "unknown", and drip the known HCl solution into it until the equivalence point but I don't know you would go about figuring out the equivalence point and consequently the pH of ocean water using this method. Is it even possible?


texts: What is (approximately) the minimum exchange current for a potentiometric measurement?

texts:
Is there a rule of thumb for what should be the minimum exchange current to detect a certain redox couple in an aqueous solution?

I would like to make a rough calculations to see whether any of my hypothesis is feasible but I have no idea about the order of magnitude an exchange current should have in water. I could find a few examples for "normal" exchange currents for pH measurements or $\ce{Fe^{3+}/Fe^{2+}}$ but no minimum.

Background: I am trying to figure out, why one can measure a negative ORP in fermentations. There has been a lot of work done on the role of the microorganisms and their exofacial sulfhydryl groups. However, the question of WHAT is actually measured/happening at the electrode has not been answered.
I want to tackle this as part of my thesis and I can think of two mechanisms:
A) Direct interaction of sulfhydryl groups with the electrode surface
B) Mediation, e.g. via Fe or Mn ions.
My concerns about A are that cells are pretty big compared to ions so I am not sure whether enough cells could ever interact with the electrode to make this scenario realistic. In the case of B I am not sure if the concentrations are high enough.

Apologies if my language is too sloppy.


texts:
This is the molecular orbital diagram for nitric oxide:

Now, we know that nitric oxide can dimerize. However, why does nitric oxide dimerize as to form an $\ce{N-N}$ bond? Why not an $\ce{O-O}$ bond? Wouldn't the lone electron be more likely "possessed" by the oxygen since oxygen is more electronegative (if we were to step away from molecular orbital theory for a second).

Is this a Coulombic effect? Oxygen, by nature of being more electronegative, attracts more electron density to itself. This in turn would weaken any hypothetical $\ce{O-O}$ bond due to electron-electron repulsions.


texts: ChemDraw: how to change the default aromatic ring style for drawing from SMILES

texts:
I'm a beginner at ChemDraw.
I'd like to draw a molecule from SMILES and the ring bond should be drawn like the left image:

In my case, my image is drawn like the right image.
Is there any method to change the default style setting?


texts: How to calculate the concentration H3O+ in a solution with pH=6.99?

texts:
What is the correct way to calculate the concentration $\ce{H3O+}$ in a solution with $\ce{pH}=6.99$?

Attempt 1.

  pH<7, therefore there are only $\ce{H3O+}$ particles in the solution. $[\ce{H3O+}] = 10^{-\ce{pH}} = 10^{-6.99} = 1.02 \cdot 10^{-7}$

Attempt 2.

  We have $[\ce{H3O+}] = 10^{-\ce{pH}} = 10^{-6.99} = 1.02 \cdot 10^{-7}$ and $[\ce{OH-}] = 10^{-\ce{pOH}} = 10^{-7.01} = 9.77 \cdot 10^{-8}$.   Because of $\ce{H3O+ + OH- -> 2 H2O}$ we are left with $[\ce{H3O+}] = 1.02 \cdot 10^{-7}- 9.77 \cdot 10^{-8} = 4.6 \cdot 10^{-9}$

When the pH is smaller than 6 or greater than 8, one will not notice the difference, but here it is logarithmically speaking very large. So I wonder what the correct way is?


texts: Can a NOESY NMR experiment be halted partway through and give meaningful results?

texts:
Some NMR experiments can be halted partway through the acquisition and still give perfectly valid results: The traditional 1H experiment for example. Others, like a Saturation Transfer Difference Spectrum will have errors in the magnitude of the peaks in it if it is halted, due to the fact it uses groups of pulses and takes the difference of between them.

Can the standard proton-proton NOESY pulse sequence be halted halfway through and give a usable spectrum, or will this introduce artifacts?


texts:
In a book, I read that the wave function of a system should not become infinite in a finite region and also should vanish at infinity.
For the first part I think that if wave function is infinite in finite region the normalization constant becomes zero due to which wave function vanishes.
But I am not able to find the reason behind the vanishing of wave function at infinity.
Please clarify this doubt.


texts:
Is there a publicly available API that serves physical property data for organic molecules?

Pubchem does not serve properties, ChemSpider closes property access to API calls, and Toxnet only serves html.  Im basically looking for a free programmatic interface to the kind of info in a CRC handbook. Thanks for any suggestions.


texts: steam distillation of 4-bromoaniline , why render it basic prior

texts: In the multistage synthesis of 4-bromobenzenamine, why must the solution be rendered alkaline prior to the steam distillation after the hydrolysis of 4-bromo-N-ethanoylbenzenamine?


texts:
1) Which Lewis structure is preferential of the two below? EN considerations suggest the first structure. Size/charge density suggests the second one; the second structure would likely be more stable because if we think of the halide series of binary acids - the bromide anion is more stable than the chloride anion - and hence hydrobromic acid is a stronger acid than hydrochloric acid - the sheer size of the bromide ion is able to effectively dilute its charge and overcome its lack in electronegativity.

2) I am told that peripheral atoms should have octets. Why is this so? What is the physical reasoning behind this? Does this have anything to do with minimizing the overall potential energy of the molecule - i.e. the peripheral atoms are perhaps more subject to attack than internal atoms (due to steric factors) - so molecules try to minimize such a possibility by completing the octet for peripheral atoms? On the other hand, the octet rule is more of a guideline rather than a rule.

3) What is the bond-angle of the Cl-Br-Cl bond? I am told that the bond angle is a perfect 180 degrees. What about the first structure? If we consider the first structure a resonance contributor, wouldn't that lead to a distorted/non-linear bond angle? Or would that still lead to a perfect 180 degree bond angle, because to me, it seems that all the lone pairs on the bromine can participate in resonance (if not all at once).


texts: I can only find info on sec-butanol (aka butan-2-ol) and ethanol. I need to know whether isobutanol forms an azeotrope with ethanol. Can you direct me to a legitimate info source too, please?


texts: During the decomposition of sodium bicarbonate lab, the mass of the final solid I received was less than expected. Errors?

texts:
The lab procedure that my class used can be found in the photo attachment.
The purpose of the lab was to determine the equation for the decomposition of sodium bicarbonate. The two possible equations were:

$\ce{2NaHCO -> Na2CO3 + CO2 + H2O}$
$\ce{2NaHCO -> Na2O + 2CO2 + H2O}$

I understand that the correct equation is supposed to be the first one where sodium carbonate was produced. However, through calculations using the ratio between reactant and solid product, my experiment showed that equation 2 where sodium oxide was produced is supposed to be correct.
I know that this is caused by the mass of product I produced which was 0.716 grams rather than the expected expected 1.187 grams. However, what I do not understand is what errors could have potentially lead to this less than expected mass?


texts:
Which factor drives the stability in chelated complexes?

  Stability, I guess, is supposed to be associated with a release of energy. Does something like this happen in chelated complexes?


texts: I know the traditional explanation, which says that ice has large spaces between $\ce{H2O}$ molecules because hydrogen-bonding gives it an open structure. But what does the open structure have to do with hydrogen-bonding? Why isn't a similar phenomenon observed in other species which exhibit hydrogen-bonding, like $\ce{HF}$ or $\ce{NH3}$?


texts:
Can someone explain to me the coupling pattern by proton $5$? Why is it triplet of quintet? Is it long range coupling?

I'm assuming that the proton $5$ couples to two other protons on carbon $4$. But what's next?


texts: Reduction of hemiaminal by triethylsilane / boron trifluoride

texts:
I was trying to understand how the following reaction occurs (taken from a synthesis of homopipecolic acid[1]):

I thought that triethylsilane, $\ce{Et3SiH}$, would reduce the ester to an aldehyde. However, it turns out that the hemiaminal carbon has also been reduced with cleavage of the $\ce{C-N}$ bond. How does this happen?
References:

Chiou, W.; Chen, G.; Kao, C.; Gao, Y. Syntheses of (−)-pelletierine and (−)-homopipecolic acid. Org. Biomol. Chem. 2012, 10 (13), 2518. DOI: 10.1039/C2OB06984A.


texts: How to explain molecular geometry without the help of VSEPR, valence bond, or hybridization theories?

texts:
I was taught, at the high school level, how to rationalise molecular geometries with the help of VSEPR, valence bond, and hybridization theories.

However, I have recently also come to know that these theories are outdated and have many limitations. So, how can I rationalise these geometries without the help of these theories? Can I use molecular orbital theory for that, and if so, how?


texts: I was studying carbon compounds and this popped up in my mind:


texts:
I was given $\ce{K2CrO4}$ and was asked to name the compound.

Can this be done by:

1) Determining the molecular compounds oxidation state

or

2) Does one need to memorize the polyatomic ions and that is the only way to know what is what?


texts:
I am not chemist, I am mathematician and interested in Population Balance Equations. I have a question about particle size-(breakage) energy distribution which mentioned in this article: http://www.sciencedirect.com/science/article/pii/S0032591011001458.

In this paper, author says (in top of section 3.2) he divide size and energy interval to 100 intervals. I divide size interval (0-6 mm) to 100 intervals but I don't know how can I divide energy interval. Is there anybody can help me?


texts: Regioselectivity in addition of hydrogen iodide to vinyl chloride

texts:
I encountered a question which was stated as:

  The reaction of vinyl chloride with hydrogen iodide to give 1-chloro-1-iodoethane is an example of anti-Markovnikov addition. Is this true or false?

The way I could see it, vinyl chloride has a dipole moment as shown below, since chlorine is more electronegative than the carbons in the double bond.

Therefore the carbon on the left would have a greater partial positive charge than the carbon on the right. I therefore concluded that in a Markovnikov addition, the iodine atom would add to the CH2 carbon.

Since the question states that the product is 1-chloro-1-iodoethane, with the iodine atom adding to the CHCl carbon, that would thus be an example of anti-Markovnikov addition, according to the argument above.

I was told, however, that the reaction shown above was indeed Markovnikov addition. How is this so?


texts: What would affect the rate of recharge of a lead-acid battery?

texts:
I am trying to perform an investigation regarding lead-acid batteries and would like to specifically look into the recharging mechanism. However, I realised that this might be quite difficult since the recharge equation is
$$\ce{2PbSO_4 +2H_2O->4H^+ +2SO_4^2- + Pb + PbO_2}$$
Would anything except for the voltage supplied affect the rate in which the charging takes place (or the current through the electrodes)? For example, would changing the concentration of the electrolyte affect the rate of recharge?

EDIT: I was just looking at the equation and thought that if I increased the concentration of the electrolyte, which is the sulfuric acid, it would actually cause the equilibrium to shift left, meaning that the current would be lower with higher concentrations of sulfuric acid. Is this correct?


texts: Role of tautomerism and its difference from hyperconjugation

texts:
I would like to know the role of tautomerism, if any, in increasing stability of an organic compound. Moreover, how is it different from that of hyperconjugation?

I know that hyperconjugation involves shifting of protons between adjacent
atoms in different hypothetical structures to form a practical hybrid structure.

I am not clear with tautomerism, so kindly deliver a precise explanation.


texts: What is the meaning of writing a catalyst name with two compounds split by a hyphen?

texts: In literature, sometimes I see catalysts written with "-" between elements/compounds. Does this mean the first element/compound is supported on the second, or is the second a promoter? (e.g. $\ce{Fe}$-$\ce{KCl}$).


texts: Factors controlling enzymatic phosphorylation of D-ribulose 5-phosphate

texts:
Considering the Metabolic Pathway:
http://www.genome.jp/kegg-bin/show_module?M00166

Consider the reaction R01523(the very first reaction). How is it possible to know that the compound C00199(D-Ribulose 5-phosphate) will get transformed to C01182(D-Ribulose 1,5-bisphosphate)? What are the factors on which this transformation depends? One factor I know is structure but how does structure effect this transformation? Does two similar structured compound means that one of the compound can get transformed to the other one?
Note: It ia a part of biology but a chemical reaction or transformation is basically a part of chemistry, so asked this here


texts: Do some alkyloxiranes possess surfactant properties?

texts:
As an example, i notice that decyloxirane has a long non-polar "tail" and a tiny "head" that features two polar bonds. This molecule looks not so different from a common soap to me.
Would it act as a detergent when added to an industrial lubricant or hydraulic oil?


texts: Could someone please explain the difference between m/z and m/e in mass spectroscopy

texts:
The definition:

  The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio although m is not the ionic mass nor is z a multiple or the elementary (electronic) charge, e. The abbreviation m/e is, therefore, not recommended. Thus, for example, for the ion $\ce{C7H7^2+}$, m/z equals 45.5.

Could someone please explain the definition? I found it a bit difficult to comprehend.

What is "ionic mass"?
What do they mean by "z a multiple or elementary charge"?
$\ce{C7H7^2+}$, m/z equals 45.5 -> what did they do here?


texts: Is perovskite symmetric under exchange of A and B atoms?

texts:
A perovskite is any crystal with the general formula $\ce{ABX3}$ where if the $\ce{B}$ atoms form a cube, an $\ce{A}$ atom sits in its center and the $\ce{X}$ atoms sit between neighboring $\ce{B}$ atoms.

Is the perovskite structure symmetric under exchange of $\ce{A}$ and $\ce{B}$ atoms? That is, if I replace every $\ce{A}$ atom with a $\ce{B}$ atom and vice versa, will I end up with the same exact structure as before?


texts:
HEPES, the buffer, has the chemical formula $\ce{C8H18N2O4S}$.

Using the Ionic Strength formula from Wikipedia.

I have calculated that $0.1M$ of HEPES would have a strength of $1.7M$, would it be possible to confirm whether this is correct or not? (I have little chemistry knowledge).


texts: I'm doing a DIY project on if it's possible for gelatin to be used as rocket fuel. This is just standard gelatin in a standard rocket. I know that gelatin is made from animal fat and that it has lots of sugar in it. So is it possible?


texts: Is identifying a chemical equivalent to be able to produce it?

texts:
This question is a follow up of another thread, where we are discussing Theresa May's accusation of the Russian government which is supposedly behind the recent chemical attack in the UK.

Soon after the attack the UK implemented a chemical analysis which again supposedly shows that this compound can be produced by only one government in the world: the Russian government.

So, my question is, if the UK Chemical Weapons Institute can carry out such a chemical analysis and figure out what chemical weapon was used, does it mean that they themselves possess this technology?

On 14 March 2018, at UN Security Council Russia's representative Vasily Nebenzya claimed:

  For the British specialists to be perfectly confident that this was a Novichok agent and not any other kind, they would need a control standard for proof. It [the substance used in the attack] must be compared to a control substance... They have a collection and they have the formula. In other words, if the UK is so firmly convinced this is Novichok, they have samples and formula and are capable of formulating it themselves.

Nebenzya in his speech refers to some professional chemist and I wonder what other professional chemists think of this.

Further reading:

A BBC article explaining the Novichok agent; the Wikipedia page about the same as well
Another BBC article detailing the timeline of political events.


texts: My teacher told me that order of lewis basic strength is inversely proportional to electro negativity. Comparing between iodide ion and chloride ion, chloride ion is more electronegative than iodide ion therefore iodide ion should be more basic than chloride ion but the order is reverse that is chloride ion is more basic than iodide ion. Why this is so? Is it related to localised and delocalize lone pair?


texts: Accuracy of quantum chemistry calculations on iodine neglecting relativistic effects

texts: Triiodothyronine is a molecule with three iodine atoms. If we attempted to calculate its properties with ab initio methods like Hartree-Fock or more complicated ab initio methods which included electron correlations, would neglect of relativistic effects lead to significant error in estimates of its chemical properties?


texts: Derivation of the relation between temperature and pressure for an irreversible adiabatic expansion

texts:
I have a formula for finding the final temperature in an irreversible adiabatic expansion:
$$T_2=\left[\frac{C_V+\frac{P_2}{P_1}}{C_p}\right]T_1,$$
where $T_1$ is the initial temperature.
$C_V$ and $C_p$ are the molar heat capacities at constant volume and constant pressure, respectively.

I am interested in how this formula is derived.


texts: Finding the Freundlich adsorption isotherm from the graph of log(x/m) v/s log(p)

texts:
The following problem was asked in JEE Mains 2020 (Sept 2, Shift 1),

The mass of gas adsorbed, $x$, per unit mass of adsorbate, $m$, was measured at various pressures, $p$. A graph between $\log\frac xm$ and $\log p$ gives a straight line with slope equal to $2$ and the intercept equal to $0.4771$. The value of $\frac xm$ at a pressure of $\pu{4 atm}$ is: (Given $\log 3 = 0.4771$)

I know the Freundlich adsorption isotherm formula, but I decided to write the equation of given line $( y = c + mx)$ as,
$$ \log \frac xm = \log 3 + 2\log p $$
So, the relation comes out to be,
$$ \frac xm = 3p^2 $$
On plugging $p = 4$, we get,
$$ \frac xm = 3(16) = 48 $$
But, the answer was wrong as per the official key, which mostly has genuine answers. Where am I wrong?

The answer given is,

 6


texts:
I am performing relaxed scan in Gaussian (B3LYP/6-31G(d,p)). There are two small organic molecules, one of which is a radical, the other has a benzene ring.

I'm trying to understand the optimization output. Specifically, the line Optimization completed on the basis of negligible forces. I understand that these forces are the maximum and RMS forces above.

Some examples of "negligible forces" from my output file:

        Item               Value
Maximum Force            0.000004
RMS     Force            0.000001
Maximum Displacement     0.019917
RMS     Displacement     0.004747

        Item               Value
Maximum Force            0.000002
RMS     Force            0.000000
Maximum Displacement     0.002231
RMS     Displacement     0.000490

        Item               Value
Maximum Force            0.000002
RMS     Force            0.000001
Maximum Displacement     0.003132
RMS     Displacement     0.000805

However, some small values like

        Item               Value
Maximum Force            0.000002
RMS     Force            0.000001
Maximum Displacement     0.000666
RMS     Displacement     0.000149

are followed only by Optimization completed. So what does "negligible" mean? How small do they need to be to say they are negligible? Or is this connected to at least one NO in convergence criterion section?

Next question, how reliable is optimization when such message pops up? If it's unreliable, what do I do about this? Would altering the initial geometry fix it when in only happens in a couple of scan steps?


texts: Applying the Solubility Guidelines is AgClO4 soluble or insoluble?

texts:
The book I am using is "General Chemistry: Principles and Modern Applications
by Ralph H. Petrucci. On page 158 the Solubility Guidelines for Common Ionic Solids is given. Rule 3 states that, "Salts of silver, lead, and mercury(I) are insoluble, however, my book states that $\ce{AgClO4}$ is soluble. Can someone explain?


texts: Baking Soda and Vinegar: Are there any secondary reactions?

texts:
I want to run a Lego Pneumatic Engine on the CO2 that is produced, but before I do, I want to be sure that that's the ONLY gaseous product from a real-world reaction.  Everyone seems to assume that it is, just by omission, but no one actually says it.

I'm sure it would run, but I'd rather not damage the ABS plastic or probably-steel parts (shiny metal piston shaft), or a rubber seal or the factory lubricant or something else that I can't see.  CO2 seems inert enough by itself, but is that really ALL I'll get?
(assuming of course, that I keep the foam out)


texts: What additives could make a masonry unit water-repellent but vapor-permeable?

texts:
I'm curious about some of the wondrous materials available today are able to repel liquid water but permit water vapor to pass through. I've heard that housewrap-type plastics accomplish this by being perforated with microscopic holes that are slightly too large for liquid water, but large enough for the vaporous form to pass through. I have no idea how silicate mineral paints do it, though.

Housewraps and paints are thin films, though. I'd like to learn about how such properties could be imparted to a masonry unit like a compressed earth block. Could you cast such a block with a mixture of soil and some additive that would grant this kind of water repellency but allow water vapor to pass though?


texts:
Which of the following compounds possess more than one percent enol content?

I understood that stability of enols are dependent on the hydrogen bonding in the compounds. But here, what is the significance of more than one percent enol content?


texts: Why do ionic solids change to a structure with a higher coordination number at high pressures?

texts: This seems counter intuitive to me since ionic radius increases with increasing coordination number. Surely the solid doesn't expand under high pressure? Can you explain?


texts:
Why are there two possible bond angles for the nitrous acid molecule?

After perusing Wikipedia I found that there are both cis and trans forms of the nitrous acid molecule. I also note that the cis form is sterically hindered. Could this be a reason for the two different bond angles - there are two different geometric isomers and in one case there are larger van der Waals repulsions, which in turn expands the bond angle?


texts: At which temperature does carbon monoxide explode?

texts: I had doubt whether carbon monoxide explodes or not. I checked out this resource and found out that carbon monoxide explodes when heated. But they didn't mention the temperature at which it explodes. So my question is that at which temperature does carbon monoxide explode and also at which pressure?


texts: How to rationalise the planar structre of I2Cl6?

texts:
$\ce{I2Cl6}$ is a dimer of $\ce{ICl3}$. $\ce{ICl3}$ is T-shaped, with $\ce{I}$ being $\mathrm{sp^3d}$ and having two lone pairs.

I read in Inorganic Reaction Mechanisms by R. K. Sharma that $\ce{ICl6}$ is formed by the extra two $\ce{Cl-I}$ bridge bonds. What I don't understand is, why does the bridge bond form? And is it a coordinate bond or something like a banana bond (as in $\ce{B2H6}$)?

Source: Sharma, R. K. Inorganic Reaction Mechanisms; Discovery Publishing House: 2007.


texts: Can superglue (cyanoacrylite) be thinned with acetone and still harden?

texts:
I'm looking for something with an extremely low viscosity to use as a binder for cold casting iron oxide with very fine detail (it's to make a slotted winding core for an electric motor with $\pu{1mm}$ slots). My plan is to thin out the superglue with acetone enough to make a slurry for pouring in the mold - possibly also mix in some water just before the pour to speed the setting process.

My question will superglue still harden if it has been thinned with acetone or would this destroy whatever properties that make superglue such a useful substance once it hardens? It's stated in many places on the internet that acetone works as a solvent for CA glue but this is only ever mentioned in the context of dissolving the end result.


texts:
So I was recently looking at this website.

http://www.fizika.si/magnetism/MagSusceptibilities.pdf

It lists the susceptibility values for inorganic compounds, and I've noticed that the trends don't appear to follow logic. The stronger the ligand OH, CN etc.., the larger the energy needed to reach the higher orbitals, and thus more paired electrons so a stronger diamagnetic effect, whilst the weaker ligands cause the pairing energy to be higher relative to the energy needed to go up to the higher shells, so less paired electrons so higher magnitude of magnetic susceptibility.

If one takes a look at CuI, CuBr, CuCl, and CuCN we can see that the negative susceptibility values become more positive (from -63, to -49, to -40, to -24) as ligand strength increases. Similarly, some compounds don't follow the trends of stronger ligands like $\ce{NiI2}$, to, $\ce{NiBr2}$, to $\ce{NiCl2}$. How can this be?

Also, I've tried plotting transition metal radius alongside their susceptibility values for bonding w/ Br for same oxidation states. I got a proportional relationship. Apparently, the atomic radius of the transition metal increases the susceptibility. Does this make a bit of sense? I mean, logically, larger radius essentially means larger diamagnetic and hence lower paramagnetic susceptibility values, right?


texts: How to Choose Orbitals for Hybridization

texts:
Recently, I was reviewing my textbook regarding orbital hybridization, and one of the problems was to determine the hybridization of each of the atoms in $\text{CO}_2$. I understand why the hybridization on the C atom is $\text{sp}$ and the hybridization on each of the O atoms is $\text{sp}^2$, but what I don't understand is how to determine which of the three p orbitals becomes hybridized.

This becomes especially relevant with the O atom, since in its normal state one of its p orbitals is full (2 electrons) while the other two p orbitals only have 1 electron each (meaning that the 3 p orbitals aren't interchangable). How do I know which of these 3 p orbitals become hybridized into $\text{sp}^2$ orbitals and which orbital stays as a regular p orbital?

Thanks for the help.


texts: Identifying a quadruply charged anion containing three carbon atoms

texts:
This linear polyatomic ion containing three atoms of carbon has a negative four charge and is only found bonded with lithium and magnesium.

Could anyone identify this for me? It's from a quiz bowl clue that doesn't have the answer with it.


texts: is there any evidence that there are ~75 extra elements on the periodic table?

texts: there are 118 currently existing elements on the periodic table, and recently I've found like 77 elements that quote on quote "may exist" on our periodic table. Is this true?


texts:
I have 12 experimental tables with OD(substrate concentration, time), where OD is optical density and one table with $\mu$ (substrate), where $\mu$ is growth speed. OD and $\mu$ are functions.
The experiment is "growth of proteins on a methanol substrate".

With passage of time, the concentration of substrate and oxygen is decreasing (substrate to zero, and $\ce{O2}$ to 10% from 100% and the process is terminated).

With substrate decrease the number of particles in bioreactor is growthing. I must determine the parameters $(s, \ce{O2})$ when the growth speed is $\rm max$ to $\mathrm{max }- x\%$. $x$ may be $10\%-15\%$ of $\rm max$.

I need a model to determine the functions $\mu(s)$, $\mu(\ce{O2})$ and $\mu(s, \ce{O2})$ or the max value of miu(s,o2), where $\mu$ = growth speed, $s$ = substrate concentration and $\ce{O2}$ = oxygen concentration.

I must simulate the function $\mu(s,\ce{O2})$, to observe the maximization surface(sized by $s$ and $\ce{O2}$) through variation of parameters $s$ and $\ce{O2}$. The surface formed by $s$ and $\ce{O2}$ when $\mu$ values are between $\mathrm{max}(\mu) - 10\%$ and $\mathrm{max}(\mu)$.

The volume of bioreactor is $15\:\mathrm{L}$ and the density inside is $\approx 1$.


texts: Reaction (or lack thereof) between oxygen and halogen gas

texts:
I understand that oxygen and halogens are both very electronegative elements and it would makes sense that they don't want to associate with each other at all. However, I know that oxides of halogens ($\ce{Cl2O, ClO2, ClO, Cl2O2}$ etc.) do exist. When reading about halogens, it says that chlorine gas doesn't react with oxygen gas. I tried to find the intuitive reasoning behind this phenomenon online, but to no avail.
I know that chlorine and fluorine gas can react to produce chlorine trifluoride (fluorination of chlorine), proving that two diatomic, covalent and non-polar gases of electronegative elements can react.
$$\ce{Cl2 + 3F2 -> 2ClF3}$$
Also, drawing comparison with the reaction between nitrogen and oxygen gas:
$$\ce{N2 + O2 -> NO}$$
$$\ce{N2 + 2O2 -> NO2}$$
Nitrogen's triple bond is loads stronger than the covalent bonds from oxygen or chlorine, and it can still react with oxygen gas, albeit only under extreme conditions (lightning). Is this the case with chlorine? Even so, it only makes sense that it requires a lower temperature, as the energy needed to atomize them is lower (I haven't done the calculations with enthalpy and entropy yet). I can't find any reference to a reaction such as this online, though.
Most oxides of chlorine can only be made from compounds like chlorites and chlorates or by other novel methods. Is there a reason oxygen and chlorine (or other halogens, but chlorine in particular) can't react with oxygen gas? Is there something stopping them from reacting that I don't know about? Is it due to undesirable entropy changes? Or are the reactions I mentioned special, allowing two relatively nonreactive gases to react?


texts: How to know if something will be a good oxidizing/ reducing agent? (Besides the activity of the metal)

texts:
One of first redox reaction I was taught in school, is probably single replacement. It is easy to predict cause all you need is a table of metal activity series.

But then there are more complicated or less well-known agents. Like permanganate ion, which is used commonly in determining the purity of iron.

For agents like this, how do you know if it is strong enough to reduce or oxidize the other elements?

(Is there also a table for this?)


texts: Is it safe to inhale O2 from electrolysis of a pH 13.7 KOH solution?

texts: I'm conducting electrolysis of water with a 0.25M KOH solution in water (about 14 on my pH meter) using graphite electrodes, and I was wondering if the O2 would be safe to inhale, as in an oxygen bar?


texts: Why can't Schiff's reagent distinguish between glucose and fructose?

texts: I have heard that Schiff's base only gives a positive test for aldehydes. Glucose is an aldehyde. However, I was told that glucose doesn't give a positive Schiff's base test. Is this correct? If so, how?


texts: Making a glow in the dark substance glow only when heat is applied

texts:
I want to make a glow in the dark substance that glows only if it gets warm.

How do I obtain this substance, or what chemicals to I need to mix to make it?

It's going to go in a sealed glass jar with some magnetic materials, and I'll use a magnet to move around the magnetic part (iron filings?) to heat up the substance and make it glow.

Ideally, the substance should only glow if it goes above 110 degrees Fahrenheit.
It can't be a gas, because it's going in a sealed glass jar. It also can't produce toxic fumes, but it can be toxic. Also, I don't want the magnets to be the only things to make the substance glow. I want to put it next to an oven, in the bathroom while I take a hot shower, next to the heater, or near a light-bulb as a temporary light source for when the power goes out.

I don't care if it's a solid or a liquid, or uses a state change to achieve the glow effect. However, it absolutely CANNOT be a gas, because if the glass breaks, I don't want to have all of the fire alarms going off at the same time while everyone has passed out from lack of oxygen.

An idea for a use for this:

because it's going to be warm when it's glowing, It could act as a good solid-state heater, and you could reheat it when the glow starts to fade. Kids will love it on a cold winter's night, because it's a night light that helps to warm their cold room (or their feet).

A half joke:

  Now I need to make it glow yellow when it's warm and turn cold gray
  when it's cold, and then I can say that I'm an accomplished alchemist,
  and that I can turn lead into gold!

On a serious note,
I have a budget of around $100 to make this work, but the cheapest way of doing this would be best.
However, any way of doing this will work because it will be helpful to lots of people even if I can't afford it.


texts: Thought Experiment: Applying a high frequency high voltage to methane

texts:
I am in the process of constructing a kitchen waste digester (vegetable/fruits) from which, hopefully, over time adequate methane may be collected to burn. The digester won't be complete for several months yet - a few minutes each week or so.

Anyway, if a high frequency high-voltage field were to be applied to the methane (taking due care to avoid sparks) would the methane decompose into carbon, and hydrogen? A google search seems to indicate that methane may decompose, or form a plasma; I understand there may not be a simple/straight answer for this - but a general direction would be nice to have.


texts: What is the definition of a bipolaron and a dipolaron?

texts: I wondered about the exact definition of a bipolaron? In particular, if I have an oxygen vacancy in a metal oxide and the 2 excess electrons (when forming a neutral oxygen vacancy) localise on the 2 surrounding metal atoms, is this a bipolaron? And does the term "dipolaron", for having two electrons (holes) localised at the same (metal) centre, exist?


texts: How do I solve this Ionic Equilibrium problem?

texts:
Problem :

  Equal volumes of $\pu{0.02M}$ $\ce{AgNO3}$ and $\pu{0.02M}$ $\ce{HCN}$ were mixed. Calculate
  $\ce{[Ag+]}$ at equilibrium assuming no cyano-complex formation.
  $K_{sp}(\ce{AgCN})= \pu{2.2\times10^{-16}}$, $K_{a}(\ce{HCN})=\pu{6.2\times10^{-10}}$

My solution:
Concentration of $\ce{AgNO3}$ and $\ce{HCN}$ before reacting when mixed will become $\pu{0.01M}$. Since $\ce{AgNO3}$ is a strong electrolyte it dissociates completely. So, initial concentration $[Ag^+]$ is $\pu{0.01M}$.
$$\ce{HCN<=>H+ + CN-} $$
After reaction let
$[\ce{HCN}]= \pu{0.01-x}$, $[\ce{H+}]=\pu{x}$, $[\ce{CN-}]=\pu{x}$.
Now $\ce{CN-}$ reacts with $\ce{Ag+}$
$$\ce{Ag+ + CN^-<=> AgCN}$$
Initial $[\ce{Ag+}] = \pu{0.01}$, $[CN^-]=\pu{x}$.
After reaction let $[\ce{Ag+}] = \pu{0.01-y}$, $[\ce{CN-}]=\pu{x-y}$, $[\ce{AgCN}] = \pu{y}$.
Now, $K_{a}(\ce{HCN})=\pu{6.2\times10^{-10}}= \frac{[\ce{H+}][\ce{CN-}]}{[\ce{HCN}]}=\frac{x(x-y)}{0.01-x}\approx\frac{x(x-y)}{0.01} $.
And $K_{sp}(\ce{AgCN})=\pu{2.2\times10^{-16}} = [\ce{Ag+}][\ce{CN-}] = (0.01-y)(x-y)$.
Solving these two equations I get $\pu{(0.01-y)= 8.9\times10^{-11}=[\ce{Ag+}]}$.
But the solution in my book says the answer is $\pu{5.9\times10^{-5}}$.
I don't where am I going wrong.


texts: Coming up with a Mathematical Model to Predict how long a redox reaction can last

texts:
The description of my problem is as follows:

I will like to find out how can I obtain a mathematical equation which could give me a surface plot of the current output as a function of both concentration and time from an electrochemical cell which uses the following redox equation:

O2 + 2Pb -> 2PbO

I have the following information:

Mass of Pb - 10g
A fixed concentration of oxygen gas - 20.9% over volume of air in room

Assumptions made:

Unlimited supply of oxygen
The gas is supplied at constant room temperature and pressure (25 degree Celcius and 1 atm)

Tentatively, my plan was to use Farday's Law of Electrolysis (https://en.wikipedia.org/wiki/Faraday%27s_laws_of_electrolysis) to calculate the current which flows as a result of the transfer of electrons from the redox reaction. My hypothesis is:

The magnitude of the current generated by the following reaction will be proportional to the rate of oxygen consumption.
The magnitude of the current generated will decrease over time as the rate of reaction decrease (from the decrease in concentration of Pb).

My problem is that the plot I obtained shows me that the current vs time relationship is a reciprocal one under fixed concentration of oxygen gas.

This does not agree with the experimental results I obtained which shows that current output is steady and starts decreasing after a long period of time (a few months at least). Can someone help point out my the flaw in my argument? What should I do instead to obtain the plot I described?


texts: Which of the following has maximum nucleophilicity?

texts:
Question

The answer should be (D) as the inductive effect of 3 methyl groups increases negative charge on oxygen and thus makes it a good nucleophile.But the answer is (A).


texts: Finding rate constant from a change in pressure experiment

texts:
I measured the change in pressure for the decomposition of hydrogen peroxide in the presence of a manganese(IV) oxide catalyst at 5 different temperatures:
$$\ce{2 H2O2 (l) ->[MnO2 (s)] O2 (g) + 2 H2O (l)}$$
Is there any way that I can find concentrations and then find the rate constant, $k$? And, using them, make an Arrhenius graph to find activation energy? Any help would be much appreciated.
Edit:
Change in pressure was found using a Vernier Gas Pressure Sensor. The starting concentration of hydrogen peroxide was 3% or $\pu{0.88 mol}$. The starting pressure was always around $\pu{98kPa}$. The catalyst and hydrogen peroxide were mixed together after the stopper was put on the flask. The increasing pressure was measured and the highest it went to (at $\pu{70 ^\circ C}$) was around $\pu{145kPa}$.
Here is an example of what I have done so far to try and find the rate constant to plot on an Arrhenius graph:
At $\pu{303.15 K}$:
$PV=nRT$
$\frac{P}{RT}= \frac{n}{v}$, which is the same as concentration.
$\frac{120.3}{8.314 \times 303.15} = \pu{0.477 mol dm-3}$
$\pu{0.477 mol dm-3}$ is the final concentration of oxygen created after $\pu{180s}$ had elapsed.
$\frac{\pu{0.477 mol dm-3}}{\pu{180 s}} = \pu{0.00265 mol dm-3 s-1}$
The ratio between oxygen and hydrogen peroxide is 1:2, therefore the rate at which hydrogen peroxide was depleted at is $\pu{0.0053 mol dm-3 s-1}$.
The ending concentration must be $\pu{0.88 M} - \pu{0.0053 mol dm-3 s-1} \times \pu{180 s} = -\pu{0.074 mol dm-3}$.
And this is where I think something has gone wrong... The pressure continued to increase even after this $\pu{180s}$ so I do not think the reaction went to completion.
I would then use the equation   $k =  \frac{\text{rate}}{\text{[final concentration hydrogen peroxide]}}$ to find $k$.


texts: Looking at resonance structure 1a, it doesn't seem that tropone is aromatic. However, the resonance structure 1b with $\ce{C+-O-}$ satisfies Hückel's rule for aromaticity. Is it correct to say that tropone is then aromatic?


texts: How do you know that Sodium Hydrogencarbonate is amphiprotic?

texts:
Do you just have to remember that it is?

For example, I know that substances with CHs are hydrocarbons. Does such a 'code', if you will, exist for amphiprotic substances ?


texts: why bond energy of hydrogen molecule is twice the chlorine molecule?

texts:
why Bond energy of Hydrogen molecule is greater than chlorine and HCl molecule?
Here's a link