Chemistry Stack Exchange Community Digest

Top new questions this week:

Why "monoxide" but not "diodine"?

When naming compounds, sometimes when there are two vowels in a row the second is elided: this happens for example with "mono-oxide", which becomes "monoxide" instead. Why is this ...

nomenclature terminology  
asked by Dan L 13 votes
answered by andselisk 17 votes

What are the criteria for a molecule to be chiral?

What are the criteria for a molecule to be chiral? (We frequently get questions of this type, so this is an attempt to construct a suitable general answer for duping.)

stereochemistry chirality  
asked by Zhe 7 votes
answered by Zhe 9 votes

Mechanism of Hypervalent Iodine Phenolic Coupling

I need some help understanding the hypervalent iodine phenolic coupling reaction taking place in this synthesis of morphine, the reaction uses $\ce{PhI(OAc)2}$ as the hypervalent reagent and ...

organic-chemistry aromatic-compounds synthesis phenols  
asked by FriendlyGlove 7 votes

Why do the units of rate constants change, and what does that physically mean?

Just to be clear, I do understand that the units of the rate constant k is selected to make the equation dimensionally consistent. That is not what I am asking. It should be the case that k 'means' ...

physical-chemistry equilibrium units  
asked by Aerovolo 6 votes
answered by Karsten Theis 4 votes

How is 4H‐1,4‐oxazocine aromatic?

I’ve found 4H‐1,4‐oxazocine in my chemistry book and I’m perplex as it states as aromatic: I can count 6 electrons on p orbitals which could satisfy Hückel’s $n = 1,$ but the oxygen is sp3-hybridized....

organic-chemistry bond aromatic-compounds aromaticity  
asked by Pseuronimo Stilton 4 votes
answered by Nima Soltani 4 votes

Using a H NMR spectrum to determine the structure of a protein supplement

This question is about the H NMR spectrum of creatine. Creatine is a supplement taken by athletes to increase body mass. Recently, supplements containing derivatives of creatine have been marketed. ...

organic-chemistry spectroscopy protons  
asked by dubstep 4 votes
answered by Hans Wurst 3 votes

Identifying the molecular structure of compound with sum formula C8H14O3 formula using NMR and IR spectrometry data

I am looking to identify the molecular structure of a compound with the sum formula $\ce{C8H14O3}$ using the NMR and IR spectrometry data below. I was able to figure out the molecule as My friend ...

organic-chemistry molecular-structure nmr-spectroscopy ir-spectroscopy  
asked by xavitop 4 votes
answered by Jan 2 votes

Greatest hits from previous weeks:

Why do the melting and boiling points of the noble gases increase when the atomic number increases?

What causes the melting and boiling points of noble gases to rise when the atomic number increases? What role do the valence electrons play in this?

inorganic-chemistry boiling-point melting-point noble-gases  
asked by Ali Mustafa 18 votes
answered by Immortal Player 19 votes

Can an atom have more than 8 valence electrons? If not, why is 8 the limit?

According to some chemistry textbooks, the maximum number of valence electrons for an atom is 8, but the reason for this is not explained. So, can an atom have more than 8 valence electrons? If ...

physical-chemistry electrons electronic-configuration valence-bond-theory  
asked by moonw 170 votes
answered by Terry Bollinger 95 votes

What are the dimensions of a and b in van der Waal's real gas formula?

In the van der Waal's formula for real gases $\left( p+\frac{a}{V^2}\right)(V-b)=nRT$, what are the dimensions of $a$ and $b$? I learnt that $a$ is related to the average force of attraction between ...

asked by Tejas 4 votes

Will alcohol or soap damage plastic or rubber?

I have read conflicting advice on various sites about the appropriate methods for cleaning plastic and rubber items and would like to ask people who actually know what's going on what they would ...

everyday-chemistry solvents  
asked by iconoclast 21 votes
answered by Ben Norris 23 votes

What is the pKa Range for weak acids and bases?

Am I correct in assuming that the following is true? $\mathrm pK_\mathrm a < 3$ is for a strong acid $3 < \mathrm pK_\mathrm a < 7$ is for a weak acid $7 < \mathrm pK_\mathrm a < 11$ ...

physical-chemistry acid-base ph  
asked by user2679447 4 votes
answered by ShuklaSannidhya 11 votes

Why is the 2s orbital lower in energy than the 2p orbital when the electrons in 2s are usually farther from the nucleus?

My chemistry book explains that even though electrons in the $\mathrm{2p}$ orbital are closer to the nucleus on average, electrons from the $\mathrm{2s}$ orbital spend a very short time very close to ...

energy electrons quantum-chemistry orbitals  
asked by Gordon Gustafson 83 votes
answered by Philipp 60 votes

What is the difference between the KLMN and SPDF methods of finding electronic configuration?

I've always been puzzled by this because my teachers happen to use only the KLMN method, but what is the difference between the KLMN and SPDF methods of finding electronic configuration?

asked by Madhav Sudarshan 5 votes
answered by Ben Norris 11 votes

Can you answer these questions?

What is the rationale for calling something as an 'inorganic [organic compound]'?

While studying the main groups of p-block, I have seen many compounds being labeled as an analog to some popular organic compound. For example, borazine is termed as 'inorganic benzene', while boron ...

inorganic-chemistry nomenclature boron-family  
asked by Aryan Bhaskar 2 votes

Why are isomers of parathion less active acetylcholinesterase inhibitors than paraoxon?

Parathion itself has been found to be a very weak inhibitor of acetylcholinesterase. It normally requires metabolic activation and the conversion into paraoxon in the body to actually start exhibiting ...

organic-chemistry biochemistry proteins enzymes organophosphorus-compounds  
asked by user73910 2 votes

Why would T1 relaxation time change ~20 fold between solvents for the same substance?

I have a simple, completely conjugated pyridinium salt with MW of ~300 g/mol. The molecule consists of regular non-labeled atoms (only C, H, N). If the 1H T1 relaxation time for this molecule is ...

physical-chemistry nmr-spectroscopy  
asked by A small potato 3 votes
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