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1500 questions
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4 answers
Shouldn't the pH at the equivalence point always be 7?
I learned in class that the equivalence point in an acid-base titration is reached when the solution contains an equal amount of substance of $\ce{OH-}$ and $\ce{H+}$ ions. However, in a weak acid and strong alkali titration, the pH at the…
Eliza
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Finding the number of cyclic isomers algorithmically
Is there an algorithm for finding the number of cyclic isomers a given compound might have?
I've found a general algorithm for all isomers: link, but I'm not sure how to apply it for cyclic isomers only.
JonathanReez
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Determining Kohn-Sham and Hartree Fock virtual orbitals: The underlying field
In Frank Jensen Introduction to Computational Chemistry from 2007, I stumbled upon this paragraph about whether to assign meaning to the KS orbitals or not
Another difference is that the unoccupied orbital energies in Hartree–Fock theory are…
Jes Aasbæk
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15
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What is the nature of the Fe–O2 binding in oxymyoglobin and oxyhemoglobin?
Deoxymyoglobin ($\ce{Mb}$) is known to have iron in the +2 oxidation state; I believe this was deduced from its magnetic moment, which corresponds to four unpaired electrons in high-spin $\mathrm{d^6}$ Fe(II).
However, upon binding of $\ce{O2}$…
orthocresol
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15
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Are there any non-Jahn-Teller type distortions?
My question is essentially, if ANY gradual type of deviation from a higher possible symmetric arrangement of the nuclei in a molecule is covered by the Jahn-Teller model.
More specifically I have in mind some lets say "ionic complexes" between a…
Raphael J.F. Berger
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15
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5 answers
How do manufacturer remove oxygen from metal during melting?
How do manufacturers remove oxygen from metal during melting? I melt aluminium with nichrome wires and during melting it, it forms lots of slag (aluminium oxide) and I have to remove it manually.
tattoo556
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Is there a consensus on whether amber can seal in air bubbles for millions of years?
I read about deriving the oxygen content in the atmosphere in the Cretaceous by analyzing the air trapped in bubbles in amber from that period, but I have also found papers disputing the study's methods and showing that air isn't actually trapped in…
Oosaka
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3 answers
How to calculate the height of an hcp lattice?
A hexagonal closed packing (hcp) unit cell has an ABAB type of packing. For calculating the packing fraction we require the volume of the unit cell.
Volume of hcp lattice = (Base area) $\cdot$ (Height of unit cell)
Each hexagon has a side = $2\cdot…
Sourabh Yelluru
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15
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3 answers
Why do helium balloons expand in volume as they go higher?
I realize as balloons go higher, the atmospheric pressure decreases, doing less to counteract the force of the gas particles pushing against the inner walls of the balloon. But at the same time, doesn't the outside temperature decrease, causing the…
Nick
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2 answers
Can I test for lead with household chemicals?
I picked up a metal fence loop cap today and took it home just because I liked the shape.
(^ not mine)
I cleaned it, but some of the paint is chipping off. I'm only vaguely thinking about lead, and I'm not going to chew on it, so I don't want to…
Maddy Byahoo
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1 answer
Mechanism for basic hydrolysis of α-chloronitrile to ketone?
In Corey's 1969 prostaglandin synthesis,1 compound 2 is formed from compound 1 by:
[...] treatment with 2.5 equiv of potassium hydroxide (added as a hot saturated aqueous solution) in dimethyl sulfoxide for 14 hr at 25-30°.
Can anybody explain…
Saba Tavdgiridze
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15
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5 answers
Why doesn't LiHCO3 exist in solid state?
I have read that $\ce{LiHCO3}$ does not exist in solid state. Is it because of the size of anion-cation concept or is it something else? So why is it only for lithium and not for sodium too?
Vishal M Variar
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2 answers
Does exotic potassium exist?
I was reading a book called 'Hundred and Seven Stories of Chemistry'.
There is a chapter about how the attributes of different elements can change in presence of enormous pressure and temperature. The book says in presence of enormous pressure and…
Mockingbird
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3 answers
What is the reason of the color difference for the cis/trans isomers of tetraamminedichloridocobalt(III) chloride?
The cis and trans isomers of $\ce{[CoCl2(NH3)4]Cl}$ are quite famous as one is purple and the other one is green which is a huge difference in color. Now I can't find any information to why this is the case?
I remember they told me in the lecture…
Justanotherchemist
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15
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7 answers
Which is anode and which is cathode?
A maybe (hopefully) simple question about the denotations of "anode" and "cathode". The below image is a schematic of a polymer solar cell (Source (WBM)). (The figure text is quoted as well for the sake of context).
My question is only about the…
Steeven
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