37 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

Resources for learning Chemistry

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.; ...
33 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, ...
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27 votes

Resources for learning Chemistry

Video Resources (online) The University of Nottingham's Periodic Videos The periodic table of videos includes introductions to all elements. The molecular videos section focuses on interesting ...
26 votes
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Is Hexafluorocyclohexane the "Most Polar" Small Molecule?

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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25 votes
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What would follow in the series sigma, pi and delta bonds?

tl;dr The next in the series is called φ bond. There is even a tiny Wikipedia article about it. Nicolau pointed me to the Wikipedia article, that had at the time a tiny section about the φ ...
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22 votes

Resources for learning Chemistry

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 ...
21 votes

Resources for learning Chemistry

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.; ...
20 votes

Resources for learning Chemistry

Software ChemOffice Professional Commercial software for drawing molecular structures, 3D models and many more. High price but most higher education institutes will provide students/staff with free ...
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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 ...
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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 ...
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19 votes
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What is the isomer distribution in monosubstituted fluorobullvalene?

Extensive NMR studies of substituted bullvalenes were done in the 1960's and 70's, by Oth et al. Much of their original work was published in German. Thankfully, some of these topics were revisited (...
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19 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 ...
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18 votes

Resources for learning Chemistry

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: ...
18 votes

Do symmetric hydrogen bonds in neutral molecules exist?

It appears that perhaps water may have symmetric hydrogen bonds between oxygen atoms, but it would take at least 60 GPa of pressure, or more, to make water to bond like that. I guess water stops being ...
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18 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 ...
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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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17 votes

Which substance has the highest temperature range between melting and boiling point

Gallium melts at 30 °C but doesn't boil until 2200 °C. If 30 °C is a bit too warm to count as "room temperature" or "normally" for you, I found an old paper that recommends tetralkyl ...
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16 votes

What is the isomer distribution in monosubstituted fluorobullvalene?

Let me begin by thanking Martin and long for supplying the key reference (J. Am. Chem. Soc. 1996, 118 (34), 7995–8005). Importantly, long also provided the isomer ratio I was asking for; according to ...
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16 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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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 ...
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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 ...
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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 ...
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14 votes
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What are the most extreme chemicals?

Densest gas Densest element Greatest range between melting and boiling temperature Highest melting point Lowest solubility product constant Most dangerous: Is there any substance that's a 4-4-4 on ...
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 ...
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14 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

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 ...
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13 votes
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Conductivity as a function of acid concentration

At low concentration, conductivity is proportional to concentration (a linear relationship). Each ion will have its own unique mobility, as discovered by Kohlrausch. $\ce{H+}$ has the highest ...
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13 votes
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Has a non-carbon-based form of life been discovered since 2010?

Just because an organism might need a nutrient, whether arsenic or cobalt (which homo sapiens needs for making RBC's) does not mean that the organism is not carbon-based. What had been announced was ...
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