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1500 questions
16
votes
1 answer
Splitting of $d$ orbitals when ligands approach central metal ion
In my high school chemistry book, it is written that when ligands approach the central metal ion (transition metal ion) to form dative bonds, the $3d$ orbitals split into two: two which are in higher energy level and the other 3 in lower energy…
Eliza
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3 answers
PBE vs. PBEPBE functional
I've found good explanation what the PBE functional is. However, sometimes I see PBEPBE and I cannot find any good information about what this means and how it's different from PBE.
The Gaussian manual explains PBE and also provides the reference…
DSVA
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16
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3 answers
What is the effect on humans of using dry ice and liquid nitrogen as food additives?
I have seen on a TV show that some guy uses dry ice (solid $\ce{CO2}$) to make ice cream and on an another TV show, liquid nitrogen ($\ce{N2}$) is used with tequila. Both are edible.
I know that both gases are inert, but could these gases…
Eka
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16
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6 answers
Is there a cheap, safe liquid that evaporates EXOthermically around room temperature?
The heating and AC system in the building where I occasionally work, works like this (basically a thermostat):
The administrators set some temperature that is maintained automatically. Say, in the winter, the outside temperature is 0 °C. The admins…
iammax
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16
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Why is the 2-position of pyridine electron richer than the 4 position
I am wondering about the electronic structure of pyridine.
If we look at nucleophilic substitution, which favored on electron poor centers, for 2-chloro and 4-chloro pyridine we see that the substitution in 4 position is about 5 times faster…
DSVA
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16
votes
0 answers
Tetrahedrane Properties and Analogs
I took a look into some tetrahedrane ($\ce{C4H4}$) analogs, platonic hydrocarbon, basically very strained tetrahedral geometry at every carbon. I was wondering what will be the predicted delta H of formation for the tetra nitro analog…
AS_1000
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4 answers
Easiest way (software) to visualize charge density from an .xyz file with point-charges?
I have an .xyz file which contains partial charges calculated by a Quantum-Chemistry software (NWChem).
The system looks like this, here I show the partial charges calculated from the electrostatic surface potential (using CHELPG method).
I want…
khaverim
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16
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2 answers
Is there a haloalkane for astatine?
I'm studying organic chemistry, and I noticed that there are fluoro-, chloro-, bromo-, and iodoalkanes. However, there are none for Astatine. Could someone shed some light on this, and what it would be called?
Yusuf Abukar
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16
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4 answers
What can this chemical be? (Qualitative Analysis)
I have an unknown white powder, which is an ionic solid, and I need to identify what it is by using qualitative analysis. I've run quite a few tests, but I am having a lot of trouble identifying the anion. The data I've collected is below.
General…
L. R. J.
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2 answers
Is zero-point vibrational energy an intensive or extensive property?
The zero-point vibrational energy (ZPVE) is the non-zero amount of non-electronic energy that molecules have even at zero kelvin and is purely quantum mechanical in nature. For a molecule with $c$ countable normal modes, it is defined…
pentavalentcarbon
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1 answer
Why does 2-chloropropane's mass spectrum have a peak at 27?
I have noticed that all halogenoalkanes of the form 2-Xpropane seem to have a mass spec peak at 27, implying that a $\ce{C2H3+}$ ion is being formed.
Forming a $\ce{C2H3+}$ ion, however, would mean breaking three bonds and, given its abundance,…
DividedByZero
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1 answer
What is happening in this video of solvated electrons donated from sodium in ammonia?
I just saw the Periodic Video Liquid Electrons - Periodic Table of Videos where sodium is added to liquid ammonia. The demonstration shows that even if electrons are solvated, if you have a high enough electron density, the substance will turn shiny…
uhoh
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16
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1 answer
How to name this cyclic compound with an O in it?
How to name this cyclic compound with an O in it?
I was going to name it cyclobutane, but not all of the atoms making up the ring are carbons, one is an oxygen. So, then I decided to name it butane, but that doesn't make sense because there is a…
user176105
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16
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1 answer
Determining the pH of an organic solvent
Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $\mathrm{p}K_\mathrm{a}$ of those groups. However,
How…
bobthejoe
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16
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3 answers
Why is anhydrous copper(II) sulfate white while the pentahydrate is blue, even though both have one unpaired electron?
We all know that $\ce{CuSO4.5H2O}$ is blue and it turns to $\ce{CuSO4}$ on heating which is white. I also learnt about coordination complexes and d–d transitions and how transition metal compounds are colored. Recently I came to know that…
Kartik
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