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What are the differences between the HMQC and HSQC experiments?
This afternoon, I was having some trouble with an HSQC (Heteronuclear Single Quantum Coherence Spectroscopy) spectrum I was trying to acquire, and the spectroscopist recommended I try HMQC (Heteronuclear Multiple Quantum Coherence) spectra, as they…
Canageek
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Hydration of H⁺ ion
I know that $\ce{H+}$ is not possible in water and it is present as $\ce{H3O+}$. But later on I come to know that even $\ce{H3O+}$ is not possible and that it is present as $\ce{H9O4+}$.
Why does this happen? What give that compound so much…
Ashu
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What does dl- mean in nomenclature
I came across the compound dl-stilbene dibromide, and I am confused by exactly what this means. I thought it might have meant a racemic mixture but there is only one chemical structure given.
ringo
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What is the origin of the "positive-to-negative" convention concerning dipole moments in chemistry?
I'm a physics professor who often teaches students who have taken a lot of chemistry (read: pre-meds). In physics, the dipole moment of a charge configuration is defined as pointing from concentrations of negative charge towards concentrations of…
Michael Seifert
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Why copper(I) is unstable in aqueous medium?
I am expecting that $\ce{Cu+}$ attains a $\mathrm d^{10}$ configuration by losing one electron from s-subshell. Since it has fully filled d-orbital, it should be stable. But it is found that it is unstable and tends to disproportionate in aqueous…
Nilay Ghosh
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Why doesn't nitrogen monoxide dimerize?
Why doesn't Nitrogen monoxide dimerize even though there is an odd electron present whereas nitrogen dioxide does (because of the odd electron on nitrogen)?
vpp
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Is it possible to compute the colour of *any* molecule?
Above are some spectral emission lines for hydrogen, helium and neon.
Using the Schroedinger equation, it's possible to derive the colours that hydrogen will emit when light is fired at it. A little more complicated (although beyond my rudimentary…
Meow
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Has a carbon compound ever been found having an ionic bond?
Though it is highly unlikely, has any carbon compound been found to make an ionic bond and to exhibit ionic properties?
Harshit Garg
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Symmetrize nearly symmetric molecule
In the overall good paper of Beruski et. al.,[1] an algorithm of how to symmetrize an "almost symmetric" molecule by symmetrizing the distance matrix is given for the example of Methane.
The main idea is that symmetric equivalent atoms have the same…
Rainer
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How do the molecules know the future? How do they proceed to form "Most Stable" compound?
I'm tutoring few students for Chemistry. During the course, I many times use the phrase "Out of these possibilities this one is stable. So it is formed". I get questions like, "How do the molecules know?"
Honestly I don't know. How do the molecules…
claws
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Does benzene's resonance structure allow it to enter DNA?
According to this link, benzene is able to insert itself into the human DNA. It isn't an authoritative source and appears to be quite biased, so I'm wondering if there's any truth to this.
The resonance hybrid structure of the benzene molecule…
Ben
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Why is nitrogen dioxide (NO2) brown?
I don't understand why nitrogen dioxide $\ce{NO2}$ is coloured brown when nitrate $\ce{NO2-}$ and dinitrogen tetroxide $\ce{N2O4}$ are not. I understand it is due to absorption of light when its frequency matches the energy of an electronic…
saatwik upadhyay
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Why is the van der Waals coefficient b equal to four times the volume of the particle?
In the van der Waals equation of state
$$\left[p + a\left(\frac{n}{V}\right)^2\right](V-nb) = nRT$$
the coefficient $b$ is supposed to represent the volume occupied by the particles. Why then is it equal to four times the volume and not simply the…
piyush pachauri
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Similarities and Differences between Resonance and MCSCF treatments
Recently, there has been a question by Voldemort concerning different resonance structures of $\ce{NCO-}$, requesting an explanation why one resonance structure would be more preferred than another.
There has been a little discussion on that between…
pH13 - Yet another Philipp
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Why is it that the least reactive metals are the best electrical conductors?
Silver, Gold and Platinum are amongst the best conductors of electricity, but also the amongst the most unreactive. Since electrical conductivity depends on the number of delocalized electrons (along with resistivity), if an element gives up its…
Razorlance
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