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1500 questions
21
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6 answers
What is the definition of of 'compound', 'mixture', 'element' and 'molecule'?
I am looking for the precise definitions, as I am very confused as to what they are exactly because although I mostly understand what they mean, I have encountered some conflicting definitions that confused me.
As it stands, this is what I…
Sophia
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Precedence of 1,2 carbocation rearrangement
How can one choose which group has more shifting tendency in 1,2 carbocation rearrangement? The obvious order is via the stability of the carbocation of the group. But, phenylic groups have high shifting tendency--and a phenylic carbocation is…
ManishEarth
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21
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3 answers
Oxidation state of the sulfur atoms in the thiosulfate Ion
What are the oxidation states of the two inequivalent sulfur atoms of the $\ce{S2O3^{2-}}$ molecule? For all I know is that Lewis Structure does matter in most of the cases.
Del Pate
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21
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Why is beryllium transparent to x-rays?
Beryllium has other fancy applications. It is transparent to x-rays, so it's used in the windows of x-ray tubes, which need to be strong enough to hold a perfect vacuum, yet thin enough to let the delicate x-rays out.
The quote is from the book…
favor
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21
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2 answers
What causes the really bad smell of rotten potatoes?
Rotten potatoes have a distinctive unpleasant odour, and I can't find any definitive answer as to what the chemical involved is. I was thinking it might be Butyric acid, from the fermentation of the starch, but according to Wikipedia:
Butyric acid…
stib
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21
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2 answers
Why formulate drugs as HCl salts when HCl is in stomach acid?
I know there are issues of formulation and industrial processing that make it advantageous to produce many amine containing drugs as their salts rather than as freebases. And if giving the drug intravenously, the increased water solubility is…
Sarah
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6 answers
Painting metal, does it matter if all rust is removed before?
In the context of automobile repair work, assume a metal surface has rust on it. Does it matter if all of the rust is removed before the metal surface is painted? If it does matter, then why?
It appears that at least some will claim you can do this,…
AttributedTensorField
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21
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1 answer
Raw green onions are spicy, but heated green onions are sweet. Why is this?
Raw green onions are spicy, but heated green onions are sweet. Why is this? More specifically; what change in the raw green onion's organic chemicals makes it no longer spicy when the green onions are slightly burnt, and is there some chemical…
Young Jun Lee
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21
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4 answers
Do lone pairs on substituents (e.g. in aniline) count towards Hückel's rule?
Why is aniline aromatic? Doesn't it have 8 π electrons including the lone pair on nitrogen, thereby violating Hückel's rule?
The way I see it, there are 6 π electrons from the benzene ring, and an additional 2 from the $\mathrm{sp^2}$hybridized…
Dissenter
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Why is the boiling point of fluorine lower than that of oxygen?
Fluorine boils at -188.1 °C and oxygen boils at -183 °C, but shouldn't $\ce{F2}$ boil after $\ce{O2}$?
Despite being electronegative elements, both are nonpolar molecules and posses dispersion forces as the only mean of intermolecular interactions.…
John Hon
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21
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6 answers
What exactly is temperature?
I've read at many places that temperature is the average kinetic energy of particles present in an object. I just don't intuitively get how kinetic energy is connected with temperature. And how is heat connected with temperature then? Then what…
steve wozniak
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21
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5 answers
How would I measure the Carbon Dioxide content in Coca Cola over a period of time?
I'm sorry if this is a broad question, but I am trying to plan a simple experiment. I am wondering is there a somewhat simple way of continuously measuring $\ce{CO2}$. I already know the initial carbon dioxide content is around $\pu{2.2g}$ from…
Vijay Reddy
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21
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1 answer
What happens when para-water ice is suddenly melted?
Background (hydrogen)
In the case of recently liquified hydrogen (which is quite cold of course) it must be re-equilibrated before loading on to a rocket as fuel to avoid a sudden exothermic equilibration of the ratio of the ortho- and para- forms.…
uhoh
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21
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4 answers
Why are equilibrium constants unitless?
I haven’t quite reached the point where I can read a full-fledged text on chemical kinetics and thermodynamics yet, so bear with me, please.
I’m wondering why a value like $K_\text{eq} = \frac{[\ce{NO}]^2[\ce{O2}]}{[\ce{NO2}]^2}$ wouldn't have…
readyready15728
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3 answers
What are known examples of drugs that racemize/stereoconvert in vivo, and how are they converted?
It is known that although only the (S)-enantiomer of the infamous sedative thalidomide possesses teratogenic properties, it is not very useful to administer the pure (R)-enantiomer since it is racemized within the body. Are there other known…
user95