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Why are some salt solutions coloured?

I notice that salt solutions of $\ce{NaCl}$ and $\ce{KCl}$ are colourless while those of $\ce{CuSO4}$ and $\ce{FeSO4}$ are coloured. I got as far as figuring that it has to do with the transition metal ions, but I can't explain why the salt…
jokerdino
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Symmetry lost in orbitals?

I've always thought that orbitals lead to a loss of symmetry, and have never been able to give myself a satisfactory answer to this. I'll explain via an example: Let's take an $\ce{N^3+}$ atom. It's perfectly spherical, and has no distinguishing…
ManishEarth
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How does NaCl maintain its crystalline structure?

My understanding is that $\mathrm{NaCl}$ is an ionic compound, in which $\mathrm{Cl}$ becomes (effectively) $\mathrm{Cl^-}$ and $\mathrm{Na}$ becomes $\mathrm{Na^+}$. So I understand why I would get a "sea" of particles that would stick…
soandos
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Is the ring or the chain chosen as the parent structure in octan-2-ylbenzene?

How would you name the above compound according to IUPAC rules? I see some sources say it is 2-phenyloctane, but ChemDraw and a few other sources say it is 2-octanylbenzene.
1110101001
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What makes carbon dioxide gas "sticky" in pipes?

There's some perceived wisdom where I work that when flowing $\ce{CO2}$ gas in pipes it acts somewhat "sticky", in the sense that it lingers around longer and takes more $\ce{N2}$ or air to purge out than, say, methane or $\ce{N2}$. Unfortunately,…
Alexander Johnson
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What is charge shift bonding?

Can someone explain to me charge shift bonding? I recognize that it is proposed as another domain of bonding - one different from ionic and covalent bonding. I am also told that $\ce{C-F}$ exhibits charge shift bonding. But why—and firstly, what…
Dissenter
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What is the origin of the bactericidal properties of silver in water?

I often hear that water gets purified by being in a silver vessel, which sounds plausible because of bactericidal feature of silver. What doesn't sound plausible, though, is the way it's explained: that silver releases ions into the water. Since…
Evgeni
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What is the origin of the differences between the MO schemes of O₂ and N₂?

Here are the MO schemes of $\ce{N2}$ (left) and $\ce{O2}$ (right). Why is the $\sigma$-MO formed by the $p$ AOs energetically above the $\pi$-MO for $\ce{N2}$ but not for $\ce{O2}$? Can it be explained this way: In second period elements with more…
EJC
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Is this poor laboratory safety?

I'm a formulation chemist. My co-worker, is also a formulation scientist but has no previous formal training in chemical safety or lab chemistry settings. I always work in the hood unless I’m just mixing fruit extracts or something non-volatile. My…
user98623
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Why does mercury have low melting and boiling points?

Many metals have relatively high melting and boiling points, but mercury has relatively low melting and boiling points. What are the possible reasons for this?
Naila Naveed
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Storing hydrofluoric acid before the invention of plastics

The first person to synthesize hydrofluoric acid in large quantities was Carl Wilhelm Scheele in 1771. This acid is known for its ability to corrode glass and metals. What materials were the containers in which it was stored before the invention of…
Ginasius
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What is the role of ammonium chloride in the workup of a Grignard reaction?

In the following Grignard reaction, why is aqueous ammonium chloride used to get to the products? I don't see how it participated in or modified the reaction from what is normally expected.
Jhagrut Lalwani
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Synthesis Golf X: TAK-457

I shall try to revive this! A full FAQ post has been written on chemistry.meta.SE, explaining the premise of synthesis golf and the 'rules'. Please take a look at this before answering (if you haven't already). TAK-457 is a drug (more accurately,…
orthocresol
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Which has stronger hydrogen bonds: water or ice?

As ice is the solid form of water and it has more hydrogen bonds than water, because it's oxygen atoms are precisely tetrahedrally positioned and each oxygen is hydrogen bonded by four neighbouring oxygen atoms. This changes the density of ice by…
Rabik John
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What's the longest C=C bond?

There's been ample work and media coverage on how to make a long C-C single bond. To my knowledge, the longest stable C-C bond is currently 1.704 Å, prepared by Schreiner Nature 477, 308–311 in 2011. All around us, there's considerable plastics,…
Geoff Hutchison
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