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17
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4 answers
How does sulfuric acid dehydrate sugars?
I know sugars have $\ce{-OH}$ groups, and that sulfuric acid is a strong acid. What I'm failing to see is how exactly sulfuric acid dehydrates sugars. Does it protonate the hydroxyl groups, making them good leaving groups? What about the case of…
Dissenter
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Is tropone aromatic?
Looking at resonance structure 1a, it doesn't seem that tropone is aromatic. However, the resonance structure 1b with $\ce{C+-O-}$ satisfies Hückel's rule for aromaticity. Is it correct to say that tropone is then aromatic?
EJC
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17
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Why do many transparent plastics turn opaque when deformed?
Many transparent plastic materials, rigid or not, turn opaque (white) when subjected to stress, deformations or when folded (if not rigid) . The effect seems to be irreversible.
What is the cause?
I would have guessed that some internal…
leonbloy
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Reaction mechanism for reduction of nitrobenzene to aniline in catalytic and acidic media
Can anyone explain the reaction mechanism of the two reactions given below?
They are the conversion of nitrobenzene to aniline in catalytic ($\ce{H2/Pd}$ in ethanol) and acidic ($\ce{Sn/HCl}$ or $\ce{Fe/HCl}$) mediums respectively.
$$\ce{Ar-NO2…
jNerd
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Why "monoxide" but not "diodine"?
When naming compounds, sometimes when there are two vowels in a row the second is elided: this happens for example with "mono-oxide", which becomes "monoxide" instead.
Why is this not always applied, e.g. with "diiodine"? Why aren't the repeated i's…
Dan L
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4 answers
Are there reactions where the stirring direction would make a difference?
I'm not a chemist. I don't really do anything with chemistry, so I know little of the subject.
I know a bit about chiral molecules. For example, I know that homochirality can affect light polarity.
I'm just curious: Are there chemical reactions…
ChocolateOverflow
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votes
1 answer
Can entropy increase during bond formation?
Recently the question was asked, "Is bond formation “strictly” exothermic?" As a corollary to that question, what is the relationship between entropy and bond formation? Does the entropy of the bond formation reaction always decrease when a…
ron
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17
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1 answer
Neutralizing a sulfuric acid spill
From my AP Chem Prep Book:
What should you do if you spill sulfuric acid on the countertop?
A) Neutralize the acid with vinegar.
B) Sprinkle solid NaOH on the spill.
C) Neutralize the acid with NaHCO3.
D) Neutralize the acid with an Epsom salt…
TheGodlyBeast
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17
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Why is the exo product formed in the Diels–Alder reaction between furan and maleic anhydride?
For most Diels–Alder reactions, the major product is endo because there are favourable interactions between the newly forming pi bond and the electron withdrawing groups of the dienophile.
Why is the reaction between furan and maleic anhydride an…
oneCoderToRuleThemAll
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17
votes
3 answers
Is there an uncertainty associated with the value 0 K for absolute zero?
When I say absolute zero, I’m not talking about the hypothetical temperature 0 K; I’m talking about the temperature at which a thermodynamic system has the lowest energy.
Everywhere I look, sites maintain that this should be –273.15 ºC, but I can’t…
gen-ℤ ready to perish
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What is the oxidation state of Mn in HMn(CO)5?
What is the oxidation state of $\ce{Mn}$ in $\ce{HMn(CO)5}$? If $\ce{H}$ has an oxidation state of $+1$, then $\ce{Mn}$ should have oxidation state of $-1$, which I'm not sure is possible.
On the other hand, if $\ce{H}$ has an oxidation state of…
Cyclopropane
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5 answers
Why isn't pressure filtration popular compared to vacuum filtration?
I want to build a DIY vacuum filtration apparatus with a bike pump but it's very difficult to find one the could be easily converted into a vacuum pump. This prompted an idea to simply build a reverse version where above atmospheric pressure is…
Francis L.
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2 answers
Why doesn't tantalum and tungsten form amalgam?
User @Poutnik has recently answered a question in which he quoted this statement from Wikipedia:
Almost all metals can form amalgams with mercury, the notable
exceptions being iron, platinum, tungsten, and tantalum.
I am not sure about the…
Nilay Ghosh
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17
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Disproportionation of Au(II)
$\ce{Cu(II)}$ and $\ce{Ag(II)}$ complexes are known to exist while $\ce{Au(II)}$ is unstable and disproportionates to $\ce{Au(I)}$ and $\ce{Au(III)}$.
My guess as to possible reasons to this effect is that $\ce{Au(II)}$ like $\ce{Cu(II)}$ and…
Maan
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How to interpret parts-per notations? Is 1 ppb equal to 1 μg/kg?
In an article I recently submitted, a reviewer asked that I provide a concentration in μg/kg instead of ppb (parts per billion), and mentions that the later is not correct. I am not a chemist, and I thought that 1 μg/kg = 1 ppb.
Is 1 ppb equal to 1…
Nakx
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