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1500 questions
21
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1 answer
Molecular chirality and optical rotation
Why does having molecular chirality result in optical rotation? The dissymetry or chirality of molecules translates to the rotation of plane polarized light, the magnitude and direction depending on the concentration and the nature of the substance.…
stochastic13
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If you put two blocks of an element together, why don't they bond?
Say you have two lumps or blocks of an element, like lithium for example, say in the form of two bars.
Why, when you bring the two bars together so that they touch each other, do they not instantly bond with each other forming one larger bar or…
Paul
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Why isn't the orbital angular momentum also considered while calculating the magnetic moments 3d transition elements?
My textbook (Chapter: The d- and f- Block Elements) makes an interesting assertion, however, without any reason to back it up.
Paramagnetism arises from the presence of unpaired electons, each such electron having a magnetic moment associated with…
paracetamol
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1 answer
Brown stains on skin after working with Tollens' reagent
I was working in the lab preparing Tollens’ reagent. When I came back home, I observed that my fingertips were brown, and I tried to wash it with soap several times but it didn't work.
It has been a day and they don't seem to go.
What may have been…
Prakhar
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21
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3 answers
Does freezing a solution with water always cause the water to separate and form the ice lattice?
I'm curious, I was trying to look into the affect of freezing a solution with water even when the solution is completely miscible. I came across something that detailed this regarding salt water and basically said when it gets low enough to freeze,…
Jimmy Hoffa
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2 answers
What is the perfect definition for chirality?
Why is chirality defined differently for organic and inorganic compounds?
Why are inorganic compounds deemed to be optically active if they have more than one of the same ligands attached to the central metal atom, but glycine is optically inactive…
JM97
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2 answers
Shape of the P1/2 Orbital
I always thought that p-orbitals had a dumbbell shape as pictured below.
(image source)
However, I was reading an article (see Table 1, item 2) that says, "...the spherical $\mathrm{p_{1/2}}$ subshell..." (my emphasis). The implication being that…
ron
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21
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2 answers
Chemical compounds responsible for the colors in flowers?
I know that anthocyanins are a class of compounds responsible for the purple colors found in flower petals.
Anthocyanins (also anthocyans; from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = blue) are water-soluble vacuolar pigments that may…
Janice DelMar
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What is a rigorous definition of gas volume, and how is the Van der Waals equation derived?
I am confused about the justification for the corrections to the ideal gas law in the Van der Waals equation: $$p=\frac{nRT}{V-nb}-a\left(\frac{n}{V}\right)^2$$
I understand that the equation attempts to correct for attractive and repulsive forces…
Sean Mackesey
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6 answers
Why do atoms need 8 electrons to stabilize?
As the title says. I have surfed all of the net but could never find the answer to this question. Why do atoms need 8 electrons to stabilize? I mean why not 7 or 5 or 10 electrons? Why specifically 8? And what does stabilization of atoms even mean?…
MartianCactus
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3 answers
Why is manganese(II) coloured although the transition should be spin-forbidden?
In every basic coordination chemistry class, at some early point the crystal field theory and LFSE will be taught, explaining that there will be an energy difference between d-orbitals (typically named $\mathrm{t_{2g}}$ and $\mathrm{e_g}$) and that…
Jan
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21
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Reduction of carboxylic acids by LiAlH4
I've read that when a carboxylic acid reacts with $\ce{LiAlH4}$ the corresponding alcohol is formed:
But when I try to think of the mechanism, I get stuck here:
$\ce{LiAlH4}$ produces $\ce{H-}$. Since $\ce{H-}$ is a strong base it should…
Quark
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5 answers
Why is the magnesium(II) ion preferred over other ions in chlorophyll?
Chlorophyll has a $\ce{Mg^2+}$ ion. Why is it preferred over other ions? For example, what happens if there is $\ce{Zn^2+}$ or $\ce{Ca^2+}$ or any other (divalent) cation instead of $\ce{Mg^2+}$?
adianadiadi
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21
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4 answers
Is activation energy temperature-independent?
I know that activation energy for a reaction is the extra energy given to the reactants to reach the threshold energy so that they can collide and react. But then, why is it said that the activation energy does not depend on the temperature?
If the…
agdhruv
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What is Q-carbon? Does it exist?
Glowing press releases and news articles in 2015 proclaimed a new allotrope of carbon. However, even the journal article is light on chemical detail (e.g. no structural formula).
What is its bond structure?
Why is it ferromagnetic? fluorescent?…
Foo Bar
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