38
votes
Storing hydrofluoric acid before the invention of plastics
In the original 1771 experiment, Scheele used a very simple setup consisting of a glass retort with a glass receiver (round-bottom flask).
Yes, the glass was etched to some degree by the fumes, but ...
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35
votes
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Which is the currently accepted mechanism of a Wittig reaction?
tl;dr: I don't think there is any mechanism that is 100% correct, and, in cases like this especially, I think it would completely depend upon what set of carbonyl/ylid/base/solvent etc. was used. But, ...
- 17.2k
21
votes
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How can benzaldehyde have a pKa of 14.9?
Significant amount of geminal diol of benzaldehyde exists in an aqueous solution of benzaldehyde at 25 °C because $\mathrm{p}K_{\text{hyd}} = 2$ (Ref. 1)
The $\mathrm{p}K_{\mathrm a}$ of benzyl ...
- 41.1k
20
votes
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Theoretical basis behind orbital correlation diagram for pericyclic reactions
Introduction
Instead of the usual cycloadditions (which has some extra complications in terms of the reacting orbitals), let's consider the concerted reaction $\ce{H2 + D2 -> 2HD}$. We'll come ...
- 71.7k
20
votes
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Melting point of aspirin, contradicting sources
Wolfram company doesn't conduct any experimental determinations of physical constants for chemical compounds and uses literature data sources.
The webpage for ChemicalData Source Information lists ...
- 38.4k
18
votes
Do symmetric hydrogen bonds in neutral molecules exist?
This question crossed my mind during a lab today because we were making $\ce{Ni(dmg)2}$, which is shown below.
Well first, this is charged in some sense, but it is net-neutral. Also, the ...
- 13.1k
18
votes
What is the least dense liquid under normal conditions?
Isopentane $\ce{C5H12}$ has the density of $0.6201~\mathrm{g\,cm^{-3}}$ at $20~\mathrm{^\circ C}$ [1, p. 3-330].
References
Haynes, W. M.; Lide, D. R.; Bruno, T. J. CRC Handbook of Chemistry and ...
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18
votes
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Does the largest known cycloalkane contain 288 carbon atoms?
According to Makromol. Chem., Rapid Commun. 1985, 6 (3), 203–208[1], Kwang Sup Lee and Gerhard Wegner, attempting the synthesis and study of $n>100$, $\ce{C_nH_{2n}}$ cyclo-alkanes and linear ...
- 7,050
17
votes
Is Hexafluorocyclohexane the "Most Polar" Small Molecule?
At first I checked common organic compounds and solvents in CRC Handbook [1, 9-59] that have dipole moment above $\pu{4.5 D}$:
\begin{array}{llrr}
\hline
\text{Name} & \text{Formula} & \text{...
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16
votes
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Caffeine molecule representation and orientation
Wondering if there are IUPAC rules or conventions about structure orientation.
There are recommendations, which aren't really rules per se (in fact even the IUPAC nomenclature books are all ...
- 71.7k
15
votes
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Storing hydrofluoric acid before the invention of plastics
Based on research inspired by andselisk's answer, chemists stored it in glass vessels coated in wax (similar to the receiver setup Scheele used to prove the silicon dioxide precipitate was from the ...
- 266
15
votes
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What is "super" in superphosphate?
The term superphosphate is really old, even well before the concept of atoms was proposed by Dalton. Therefore it is difficult to rationalize the choice of this terminology.
In the unabridged version ...
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14
votes
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What is "gold number"?
A red gold sol is a colloidal suspension of gold nanoparticles with average size of particles less than 100 nm. The suspension is quite stable — the nanoparticles don't aggregate because of the ...
- 2,098
14
votes
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What are introductory level books on chemical engineering?
I'm studying chemical engineering for more than two years and what I can tell you is that there is not really a lot of "good" books you may read as an introduction.
You have to understand ...
- 4,205
14
votes
Density range of table salt?
The density of $\pu{2.17 g/cm³}$ refers to the density within a crystal of NaCl. In chemical engineering, the terms of powder density, tapped powder density and settled apparent density take into ...
- 30.5k
13
votes
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Is there an iron–iron bond in diiron nonacarbonyl?
tl;dr: There probably isn’t an Fe–Fe bond. We should probably stop drawing an Fe-Fe bond. Textbooks and lecturers should really stop teaching students that there is an Fe-Fe bond. But all that said, ...
- 17.2k
12
votes
List of functional groups in a molecule
Norbert Haider from the University of Vienna has been working on the identification of functional groups for quite a while.
You might want to have a look at his checkmol/matchmol tool, which natively ...
- 44.1k
12
votes
What is "chemical pressure"?
External and internal pressure
To study the effect of pressure on properties of a solid, is equivalently to learn how changes in volume transform physical parameters. For external pressure at ...
- 7,159
12
votes
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Image of crystal structure
I recommend to fetch the crystal structures of inorganic compounds via specific Google search pattern site:crystallography.net <keyword(s)>, e.g. in your case
...
- 38.4k
12
votes
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Inorganic chemistry handbook with reaction lists
An Intro in Russian edition of Reactivity of Inorganic Substances by Lidin et al. claims its uniqueness:
Настоящее пособие носит информационно-справочный характер, не имеет аналогов в отечественной и ...
- 38.4k
12
votes
What is the least dense liquid under normal conditions?
According to
Hans Jaffe: Eine metallische Verbindung von Lithium mit Ammoniak. Elektrische Leitfähigkeit und galvanomagnetische Effekte. Z. Physik 93, 741–761 (1935) https://doi.org/10.1007/...
- 12.2k
12
votes
What is "super" in superphosphate?
Superphosphate is a name used in agriculture, therefore, it does not mean the same super in the superoxides. There are two important types of fertilizers in agriculture: Nitrogenous and phosphatic ...
- 41.1k
12
votes
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Does high pressure reverse reaction between zinc and sulfuric acid?
As a very rough estimation of pressure when the hydrogen redox potential equals zinc standard redox potential, we can use the extrapolation of the Nernst equation:
\begin{align}
E^\circ_\ce{Zn/Zn^2+} &...
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11
votes
Is Hexafluorocyclohexane the "Most Polar" Small Molecule?
Calicene ($4.66~\pu{D}$, 14 atoms) and its derivatives are also good candidates.
For Hexaphenylcalicene, a hydrocarbon with 74 atoms, a dipole moment of $6.3~\pu{D}$ has been reported.[1] 2,3-dicyano-...
- 7,260
11
votes
Do symmetric hydrogen bonds in neutral molecules exist?
In Schaefer's paper,[1] which you linked, the authors describe nitromalonamide as being the compound with the lowest calculated barrier to intramolecular proton transfer, or tautomerisation.
Earlier ...
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11
votes
Do modern dispersion-corrected DFT methods give more accurate molecular geometries?
I am afraid I do not know of a paper specifically discussing the effects of DFT dispersion corrections on intramolecular properties. However, it should be noted that for short-range descriptors (such ...
- 23.8k
11
votes
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Modern open-source tools for simulation of NMR spectra
In Org Biomol Chem 2016, 14, 3943, Goodman reports the replacement of some "tradition" (expensive) programs with free/open-source ones, as applied to their dp4 method.
Specifically:
Molecular ...
- 17.2k
11
votes
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Radius of hydride (H⁻) ion
Unfortunately, there is no caliper-like tool to measure ionic radii directly.
They are determined based on experimental data such as crystal structure or crystal lattice energy using empirical ...
- 38.4k
10
votes
Accepted
What is the structure of trifluoromethanesulfonic acid in the gas phase?
Has the structure of trifluoromethanesulfonic acid or a structurally strongly related acid been studied in the gas phase? (Please provide a reference)
Yes. See Gas Phase Structure of Methyl ...
- 40.9k
10
votes
Serious introduction to the chemistry of explosives recommendation
To be clear, that is absolutely not what I'm after. I want an academically oriented introduction, not some "recipe" book.
I'm glad to read that!
I'm aware of Chemistry of Energetic Materials (Eds. ...
- 44.1k
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