Most Popular
1500 questions
44
votes
2 answers
Why does CaCO3 react with HCl, but not with H2SO4?
I have a wonderful reaction of marble chips, $\ce{CaCO3}$, with hydrochloric acid, $\ce{HCl}$, and carbon dioxide was released beautifully (fast, large volume, easy to measure and makes good visual effect too). But there is no reaction between…
Sleepy Hollow
- 960
- 4
- 13
- 26
44
votes
4 answers
What is more acidic: D3O+ in D2O or H3O+ in H2O and why?
What is more acidic:
$\ce{D3O+}$ in $\ce{D2O}$
or
$\ce{H3O+}$ in $\ce{H2O}$
and why?
I think it's $\ce{D3O+}$ in $\ce{D2O}$ as I saw somewhere that this property is used in mechanistic studies (the inverse isotope effect), but I need a proper…
EJC
- 14,302
- 15
- 67
- 157
44
votes
7 answers
Why is BCl3 a monomer whereas AlCl3 exists as a dimer?
What makes dimerization possible in $\ce{AlCl3}$? Are there 3c-2e bonds in $\ce{Al2Cl6}$ as there are in $\ce{B2H6}$?
Papul
- 1,332
- 3
- 13
- 21
44
votes
3 answers
Carbon atoms at the edge of a diamond
It is well known (the simplest textbook example) that a diamond has a well-defined arrangement of sp3 carbon atoms, as each atom is connected to four others in a tetrahedral structure.
But what about the last carbon atoms at the edge? For each of…
jimyy
- 855
- 2
- 8
- 10
43
votes
10 answers
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 orbitals.
Why is there no set of rules to follow which…
Tyler M
- 533
- 4
- 10
42
votes
1 answer
In what way could benzoin give Tollen's test?
In Q29 of Joint Entrance Exam (JEE) 2016 India, the official answer key mentions that benzoin gives Tollen's test. However, I saw this post which says that it doesn't: Why do α-hydroxy ketones give Tollens' test?
Benzoin:
I'm very confused now. If…
Jeevesh Juneja
- 739
- 7
- 10
42
votes
4 answers
Do symmetric hydrogen bonds in neutral molecules exist?
As far as I know, there have only few truly symmetric hydrogen bonds been observed. Unquestionable is the existence of it in the bifluoride ion, $\ce{[F-H-F]-}$, see also here. There are a couple of more, like in a water hydroxyl complex…
Martin - マーチン
- 44,013
- 13
- 159
- 319
42
votes
3 answers
What is the difference between ∆G and ∆G°?
In Brady's Molecular Nature of Matter, I read that $\Delta_\mathrm{r} G^{\circ}$ is $\Delta_\mathrm{r} G$ at $25~^\circ\mathrm{C}$. But later, it gives a value for $\Delta_\mathrm{r} G^\circ$ at another temperature.
What is the meaning of…
Vieri_Wijaya
- 511
- 1
- 7
- 9
42
votes
7 answers
Is there any chemical that can destroy PTFE or Teflon?
Polytetrafluoroethylene was discovered by accident. It now is an important material in the industry mainly because of its extremely high bonding energy, which prevents corrosion, halts reaction, and reduces friction (yeah carbon-fluorine bonds!)
And…
HyperLuminal
- 2,227
- 4
- 19
- 28
42
votes
6 answers
Can an atom bond with more than 8 other atoms?
Is it possible for an atom to bond with 8 other elements (same or other type)? If yes, then please give some examples. If no, then what could be the possible reason for it?
My question is not about valence shell electrons. My question is about…
Anoneemus
- 979
- 2
- 11
- 22
42
votes
2 answers
How can the dipole moment of carbon monoxide be rationalised by molecular orbital theory?
Despite the fact that oxygen is much more electronegative than carbon, the bond in $\ce{CO}$ presents a weak dipole moment.
This observation can easily be explained using the concept of "dative bond", that is, one bond is formed with two electrons…
Isaiah G.
- 673
- 1
- 6
- 6
42
votes
3 answers
Why do impurities lower the melting point of an isolated substance?
It is known that impurities in a desired isolated product lower the melting point of the mixture, even if the impurities' melting point is much higher than the desired product. Why is that so?
LanceLafontaine
- 1,742
- 1
- 17
- 22
42
votes
2 answers
Difference between shells, subshells and orbitals
What are the definitions of these three things and how are they related? I've tried looking online but there is no concrete answer online for this question.
Amuna
- 1,193
- 6
- 23
- 28
42
votes
1 answer
Why is the vanadium(3+) ion paramagnetic?
I know that the electron configuration of vanadium is $[\ce{Ar}]\mathrm{4s^2 3d^3}$.
None of the electrons in the 3d subshell are paired. Once it loses these three electrons, shouldn't the remainder of the electrons be paired? How can $\ce{V^{3+}}$…
Zolani13
- 1,105
- 3
- 12
- 11
42
votes
2 answers
Why do SN1 and SN2 reactions not occur at sp2 centres?
I was told in my organic chemistry course that $\text{S}_\text{N}1$ and $\text{S}_\text{N}2$ reactions did not occur at $\text{sp}^2$ centres. When I asked why, I was not given a satisfactory explanation. For $\text{S}_\text{N}2$ it was suggested…
Jordan Barnes
- 575
- 1
- 4
- 7