Chemistry Stack Exchange Community Digest

Top new questions this week:

Why is chemistry unpredictable?

Disclaimer: I am not a chemist by any means, and I only have knowledge limited to what I learned in my university's Chemistry III course. Basic understanding of everything up to valence electron ...

physical-chemistry experimental-chemistry theoretical-chemistry process-chemistry  
asked by Tyler M 15 votes
answered by orthocresol 20 votes

Placed in equivalent freezers, would a liter of water or a liter of lava turn from liquid to solid first? (question from a 6 year old)

Placed in equivalent freezers, would a liter of water or a liter of lava turn from liquid to solid first? (question from a 6 year old) Based on this page in a “Blaze” book, my six year old asked “...

thermodynamics  
asked by T.D. Smith 11 votes
answered by theorist 17 votes

Why does diethylmethylamine have such a low melting point?

According to PubChem, diethylmethylamine has a remarkably low melting point of $-196.0\ \mathrm{^\circ C}$. This is substantially lower than the melting points of dimethylethylamine ($-140.0\ \mathrm{^...

phase intermolecular-forces melting-point  
asked by Thorondor 6 votes

Why is work and heat energy always viewed from the perspective of the system?

So my answer was 3 and it was wrong, And i really would like to know what is the correct answer, after giving it some thought, I think the answer is 4 because indeed it is easier to control the system ...

thermodynamics  
asked by Stormin nn 6 votes
answered by M. Farooq 5 votes

Which textbook is this image on protein tertiary structure from?

I am trying to find the original textbook image that is the inspiration for many schematic figures showing tertiary interactions (hydrogen bonding, ionic interactions, hydrophobic interactions, ...

biochemistry structural-biology  
asked by Karsten Theis 6 votes
answered by andselisk 4 votes

"Nivea Sun protect & refresh" melted my tub

I stupidly applied spray sunscreen on my children inside our white, acrylic bathtub and the floor ended up with a white, very sticky residue that rubs off on things, but will not wash away with ...

solvents plastics  
asked by Bart Yarborough 4 votes

Absorption and Emission at same wavelength?

Is it possible for a molecule to absorb and emit at the same wavelength? What is the reason behind it? I’m working on charged Tin porphyrins and got the excitation and emission (fluorescence) ...

computational-chemistry absorption fluorescence td-dft emission  
asked by Pavithra J 4 votes
answered by porphyrin 4 votes

Greatest hits from previous weeks:

White powder observed after boiling water in electric kettle for many weeks

I used my water kettle (metal ones, not the plastic ones) to boil my water. Usually, if I did not consume all the water in the kettle and the water was cold, I usually topup extra water to the kettle ...

water  
asked by Jack 13 votes

Reaction between NaOH and CO2

So I wanted to know what the reaction between sodium hydroxide and carbon dioxide can be, and upon research I got 2 answers. The first one is $$\ce{CO2 + NaOH(aq) -> NaHCO3(aq)}$$ and the second ...

inorganic-chemistry acid-base reaction-mechanism aqueous-solution  
asked by user510 5 votes
answered by user213305 4 votes

Melting points and boiling points of primary alcohols do not follow the same trend

If one considers boiling points (in °C) of primary alcohols, one finds the following: methanol: 65 ethanol: 79 1-propanol: 97 1-butanol: 117 1-pentanol: 138 This trend is due to Van der Waals forces ...

organic-chemistry physical-chemistry boiling-point melting-point  
asked by mannaia 2 votes
answered by Nicolau Saker Neto 3 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 ...

gas-laws  
asked by Tejas 4 votes
answered by Ben Norris 6 votes

Why does chlorine have a higher electron affinity than fluorine?

Since fluorine has its valence electrons in the n=2 energy level, and since chlorine has its valence electrons in the n=3 energy level, one would initially expect that an electron rushing towards ...

periodic-trends electron-affinity  
asked by abhishek 23 votes
answered by ashu 14 votes

How do non-polar substances dissolve in non-polar solvents?

The case of polar solvents is clear to me - we get an attraction between opposite charges. However, how do non-polar substances dissolve in non-polar solvents? How could it be explained on a molecular ...

solvents intermolecular-forces  
asked by Stanpol 27 votes
answered by Ben Norris 29 votes

Calculate the pressure of the gas samples as indicated by the manometer

Part A) Given a barometric pressure of $\pu{764.0 mmHg}$, calculate the pressure of gas sample (a) as indicated by the manometer. Part B) Given a barometric pressure of $\pu{764.0 mmHg}$, calculate ...

physical-chemistry pressure  
asked by David Buffkin 2 votes
answered by Todd Minehardt 2 votes

Can you answer these questions?

Coordination compound nomenclature for [Cu(acac)(bpy)]BPh4

The title says it all really. I thought it would be acetylacetonatobipyridinecopper(II) tetraphenylborate. Is this correct? I feel as though it looks a bit clumsy and wasn’t sure if I was supposed to ...

nomenclature coordination-compounds  
asked by Marina Calder 2 votes

Units to use in Morse potential Equation

I am to graph the Energy potential curve (in $\text{cm}^{-1}$) for a molecule (HI),in the fundamental electronic state, according to the Morse oscillator. I believe I am to use this equation $$E(R)=...

physical-chemistry  
asked by user100003 2 votes

Misconception in valence bond theory

Since the overlap increases with directional properties of orbital, $$\ce{p - p > s - s > s - p}$$ However it is also observed that the bond strength of $$\ce{H-F &...

bond orbitals valence-bond-theory  
asked by newbie105 2 votes
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