Most Popular
1500 questions
17
votes
1 answer
When we heat a borax crystal, why does it first expand and then contract?
In the borax bead test, we take a crystal of borax and then heat it.
A small loop is made in the end of a platinum or nichrome wire (as used in the flame test) and heated in a Bunsen flame until red hot. It is then dipped into powdered borax, and…
ManishEarth
- 15,177
- 14
- 76
- 114
17
votes
1 answer
Quadrupole moment of a molecule
What is a quadrupole moment of a molecule and how does it arise? How is it measured for a particular molecule?
I've read the Wikipedia article on quadrupoles and understand that it has to do with the distribution of charge, but I'd like a more…
EJC
- 14,302
- 15
- 67
- 157
17
votes
2 answers
Rock that transfers image
This is a question that has been bugging me for over 15 years!
In high school while studying elements our teacher showed us a clear white rock or element.
It was simply flat on both sides but when placed on a sheet of paper would transfer the…
Frank
- 459
- 2
- 8
17
votes
2 answers
Is the cyclopropenyl anion antiaromatic?
According to my book, a compound is antiaromatic if it is cyclic, planar, and possesses a fully conjugated system of p-orbitals with $4n$ π-electrons.
However, I have also been told that the cyclopropenyl anion is neither aromatic nor…
Henry
- 433
- 3
- 6
- 11
17
votes
2 answers
How to rationalise with MO theory that CO is a two-electron donor through carbon?
A question I am looking at is as follows:
$\ce{CO}$ is isoelectronic with $\ce{N2}$. Sketch MO diagrams for $\ce{CO}$ and $\ce{N2}$. Point out key differences between the diagrams and use the diagram to explain why $\ce{CO}$ acts as a two-electron…
Adam
- 171
- 1
- 1
- 4
17
votes
2 answers
Is the specific heat capacity of liquid iron constant?
Does liquid iron have a constant specific heat capacity? Everywhere I've looked (save one sourceless online reference to $c_p = 611\ \mathrm{J\ kg^{–1}\ K^{–1}}$ here), I find no value listed for liquid iron. Is this because the heat capacity is…
Excellll
- 281
- 2
- 6
17
votes
1 answer
Is it possible that diamond can be grown from aqueous solutions?
Assume a cubic diamond crystal with hydrogen-terminated surface bonds. The terminating hydrogen atoms will form pairs that are geometrically close together in alternating diagonal pairs (think of the rectangles on corrugated walking steel).
Next,…
Terry Bollinger
- 3,708
- 14
- 25
17
votes
1 answer
Does acetic acid give a positive result with the iodoform test?
Acetic acid contains a $\ce{-COMe}$ group, so theoretically, it should give a positive result in the iodoform test (i.e. a yellow precipitate of $\ce{CHI3}$ being formed).
But apparently the iodoform test is used to distinguish between acetic acid…
rishab bairagi
- 387
- 2
- 4
- 8
17
votes
1 answer
What material are heat bags made of?
I just bought a heat bag from store and it has special property.
It is made up of transparent plastic bag and transparent unknown liquid inside when sold. There is a tiny circular metal piece in there. If you bend the metal piece, crystalization…
lamwaiman1988
- 273
- 2
- 5
17
votes
1 answer
What is the mechanism for oxidation of ketones by the Popoff's rule?
Ketones are relatively much harder to oxidise, but they do undergo oxidation reactions at extreme temperatures. Our teacher also told us about Popoff's rule which states that, on oxidation of unsymmetrical ketones, the $\ce{>C=O}$ group remains with…
nilanjana
- 863
- 1
- 9
- 12
17
votes
3 answers
Why do Magnesium and Lithium form *covalent* organometallic compounds?
Lithium and magnesium are Group 1 and Group 2 elements respectively. Elements of these groups are highly ionic, and I've never heard of them forming significantly covalent inorganic compounds.
Yet these elements form a variety of organometallic…
ManishEarth
- 15,177
- 14
- 76
- 114
17
votes
2 answers
How to determine gerade & ungerade symmetry of a MO orbital?
J.D.Lee writes in his book Concise Inorganic Chemistry:
[...] An alternative method for determining the symmetry of the molecular orbital is to rotate the orbital about the line joining the two nuclei and then rotate the orbital about the line…
user5764
17
votes
1 answer
What is the mechanism of the Clemmensen reduction?
I have learned that we can reduce a ketone to an alkane using the Clemmensen reduction, where we treat the ketone with amalgamated zinc in the presence of $\ce{HCl}$.
My book didn't mention the mechanisms for this type of reaction and I couldn't…
Newton
- 1,195
- 1
- 13
- 29
17
votes
1 answer
Are chiral quasicrystals possible?
Quasicrystals are materials that have long-range atomic order but lack the translational symmetry of conventional crystals. All quasicrystalline tilings and packings I have read about thus far, whilst lacking translational symmetry, have rotation…
Richard Terrett
- 10,800
- 2
- 51
- 69
17
votes
3 answers
Is there a point at which Ethanol (E10) fuel becomes harmful to gas tanks or engines if not used?
This is not the typical chemistry question on this website, but I think it's an important practical question.
When I got a gas string trimmer, the woman who worked at the gardening shop told me that E10 (fuel commonly sold in the USA - 10% Ethanol,…
chrishiestand
- 273
- 2
- 5