pH13 - Yet another Philipp
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Acid Accident Treatment
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42 votes

My Lab First Aid book$^{*1}$ tells the following: The local therapy mainly consists of the instant, intense rinsing (at least 10 minutes) with tap water (ideally 15 to 20 °C). Don't try to ...

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Resources for learning Chemistry
34 votes

Books about Inorganic Chemistry General texts Housecroft, C. E.; Sharpe, A. G. Inorganic Chemistry, 4th ed.; Prentice Hall: Upper Saddle River, NJ, 2012. Weller, M.; Overton, T.; Rourke, J.; ...

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Is Hexafluorocyclohexane the "Most Polar" Small Molecule?
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26 votes

At first, I thought, that those 6.2 D of O’Hagan et al. have been measured somehow but it as later described, they calculated it (1): A molecular dipole value of 6.2 D for 1 was calculated at the ...

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Resources for learning Chemistry
21 votes

Online Courses Chemistry LibreTexts This collection was formerly known as UC Davis' ChemWiki: The Dynamic Chemistry Hypertext. It is a collaborative approach toward chemistry education where an Open ...

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Calculating the pH of a highly dilute solution of HCl
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21 votes

At first you have to think of where the protons come from. That is as you mentioned it, hydrochloric acid (for every chloride ion in solution there has to be a proton) and water (for every hydroxide ...

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Resources for learning Chemistry
20 votes

Books about Analytical Chemistry Schwarzenbach, G.; Flaschka, H. A. Complexometric Titrations; Methuen: London, 1957 (translated by H. Irving in 1969). Skoog, D. A.; West, D. M.; Holler, F. J.; ...

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Resources for learning Chemistry
18 votes

Books about General Chemistry Atkins, P. W.; Jones, L. L.; Laverman, L. E. Chemical Principles: The Quest for Insight, 6th ed.; W. H. Freeman: New York, 2012. Silberberg, M.; Amateis, P. Chemistry: ...

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Sp5 hybridization in cyclopropane?
18 votes

Until this post, $\mathrm{sp^1,~sp^2~\text{and}~sp^3}$ meant for me, that the hybrid orbitals would consist from one s orbital and one, two or three p orbitals. I thought of it being so, as this seems ...

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What's the longest C=C bond?
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12 votes

While the two other (so far) presented molecules look realistic (Martin) or are real (Marko), I couldn't find the constraint, that the molecules actually need to be realistic, so here we go. This is ...

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Does the number of H+ ions in solution go up on dilution of a weak acid?
12 votes

Let's say we have got a solution of an acid with a pK$_a=5$. The resulting pH dependent on the concentration of that acid would be like: $\hskip2in$ Examples: $0.1~\ce{M}$: pH$=3.0$; $0.001~\ce{M}$:...

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What is "ölsaurem Alkali"
11 votes

They were writing it fancy in old times. Sodium acetate would have been "essigsaures Natrium", potassium sulfate "schwefelsaures Kalium" and so on. Therefor, "ölsaures Alkali" is an alkali salt of ...

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Short Cut Method to Calculating pH of Polyprotic Acid?
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11 votes

The assumption that the second (and higher) deprotonation steps are negligible for the calculation of the pH of a polyprotic acid is valid for citric acid. You can compare this by calculating the ...

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Discrepancies between smell and taste
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11 votes

The food that you eat regularly is something that you are used to. You know exactly which smell combines with which taste ... but that does not imply that the chemicals you smell are the same that you ...

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What is the highest known bond order?
10 votes

In the paper that you've mentioned$^{\ast1}$, there is something described, which is called effective bond order ($\mathrm{EBO}$). $$\mathrm{EBO} = \frac{1}{2}\left(\sum_{i=1}^N \eta_{b,i}-\eta_{a,i}\...

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Why is a theoretical titration curve higher than a practical one?
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10 votes

One thing that that has already been mentioned in the comments is the impact of $\ce{CO2}$ on the equilibrium. If you look at the following figure you can see the pH diagram of carbonic acid. The ...

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How to analyze a acid and salt mixture using titrimetry?
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10 votes

Prologue The following will show you not only how to sketch a titration curve but how to produce an analytical form of a titration curve. So this might not be an easy solution even if I try to keep ...

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How to explain the discrepancy between the calculated absorption wavelength within the particle in the box theory and the observed wavelength?
8 votes

Luckily I found a source containing your molecule as an example. You need your equation for the energy difference between the HOMO and the LUMO, which is (nearly) defined as you wrote: $$\Delta E = \...

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What is the explanation of the structure of H2XeO4?
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8 votes

When I think about such structure, I draw all valence electrons around the atoms and connect them somehow reasonably. There are two ways to connect the hydrogens to xenon. Either directly bonded as H-...

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Easiest way (software) to visualize charge density from an .xyz file with point-charges?
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8 votes

I think, the easiest way is to use Multiwfn in combination with Jmol. There you can estimate/rebuild the ESP from partial charges. Multiwfn Load your xyz file with the charges into Multiwfn, which ...

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Which conformations of 2,3-dimethylbutane are more stable?
8 votes

The correct arrangement (from least stable to most stable) is probably: $4 > 2 > 3 \gtrapprox 1$ based on my calculations for the four gas phase rotamers you can see in the figure below. Your ...

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Reduction of butadiene with Na/NH3 - stereoselectivity
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8 votes

At first ... I don't like books that don't give proper solutions to their questions$^{*0}$. This doesn't help anyone ... or at least not me. Old sources I started my search on Reaxys and there are ...

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Calculate pH of a weak acid and weak base neutralization reaction
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7 votes

You have a system of an acid, an ampholyte and a base. As you are interested in the pH value, your main question is what does "produce" or "consume" them. The proton concentration for your specific ...

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When using Gaussian to calculate NMR, what's the default solvent and frequency?
7 votes

If I choose GIAO HF/STO-3G, is the default solvent $\ce{CD3Cl}$? No, the default is gas phase as usual. But you can choose whatever solvent is programmed through the scrf=(solvent=...) command. The ...

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Stability of beryllium carbonate
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7 votes

Why and how is this stability maintained? Beryllium carbonate decomposes into Beryllium oxide and Carbon dioxide. $$\ce{BeCO3 <=> BeO + CO2}$$ According to Le Chatelier's principle one simply ...

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Defining enantiomer of morphine by R/S designation
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7 votes

The structure that you are showing is neither R nor S. As it has five chirality centers you need to look at all of them. $\hskip3in$ You can see in the above figure that there are three R and two S ...

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What are the structures of potassium superoxide and xenon hexafluoride?
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7 votes

Xenon hexafluoride's geometry is not easy to be described but it is assumed to be in $C_{3v}$-symmetry - not octahedral! - in gas phase which is supported by electron diffraction measurements and ...

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Does computational chemistry get the molecular orbitals of dioxygen wrong?
6 votes

A triplet species, as your MO scheme shows, has two unpaired alpha spin electrons, which is why you don't have to look at the beta orbitals at all but you have to look, if the $\alpha$-HOMO and $\...

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How to set the memory for the Gaussian 09 cubegen utility?
6 votes

By reading the information from Gaussian about cubegen, you would find out, that use of cubegen is like the following: cubegen nprocs kind fchkfile cubefile npts format cubefile2 They further ...

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How can I perform calculations including the relativistic approximation SC-ZORA and solvent approximation COSMO in Gaussian 09?
6 votes

Gaussian can’t effectively treat relativistic effects (look up integral=dkh [1] and try its limited use. AFAIK you can only have 50 parameters in internal coordinates which is not very realistic for ...

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How to define a new solvent in Gaussian09 to run SCRF?
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6 votes

The correct input should be more like (replacing your Water2 with Generic) #p b3lyp/6-31G(2df,p) int(grid=ultrafine) SCRF(Solvent=Generic,Read) Comment 0 1 ... stoichiometry=H2O1 solventname=...

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