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Reaction of alcohols with PCl5 and PCl3
The reaction of alcohols $\ce{ ROH }$ with $\ce{ PCl5 }$ and $\ce{ PCl3 }$ yields an alkyl halide $\ce{RCl}.$ With $\ce{ PCl5 }$, the reaction is quite simple leading to the formation of $\ce{ RCl }$ and $\ce{ POCl3 }.$
But with $\ce{ PCl3 }$ a…
miyagi_do
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Why does ice cream make soda fizz?
I've noticed that adding a chunk of ice cream to soda makes the soda fizz slightly near the soda-ice cream interface. I thought it was a physical effect due to the temperature, but adding ice has no effect.
It still can be a physical effect due to…
ManishEarth
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27
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Thermodynamic vs Kinetic Sulphonation of Naphthalene
The left hand isomer is clearly the kinetically favoured product and the right hand isomer is the thermodynamically favoured product. However, I have no idea why. Can you explain?
RobChem
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27
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What is the justification for Hückel's rule?
I know that experimentally, the rule has been verified but I am having trouble understanding why it works. I see no reason why equivalent cyclic structures can undergo resonance and be just as stable. Any clarification would be nice.
CognisMantis
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27
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Why does water evaporate spontaneously at room temperature despite ΔG > 0?
Standard Gibbs free energy of formation of liquid water at $\pu{298 K}$ is $\pu{−237.17 kJ mol-1}$ and that of water vapour is $\pu{−228.57 kJ mol-1}$ therefore,
$$\ce{H2O (l) -> H2O (g)}\qquad\Delta G =\pu{8.43{kJ mol-1}}$$
Since $\Delta G>0$, it…
Apoorv
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27
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How does Palladium dissociate H₂ so easily?
If I understand correctly, $\ce{H2}$ in the presence of $\ce{Pd}$ readily dissociates as it dissolves into the metal. With the dissociation energy for the $\ce{H—H}$ bond being so large, how is this possible?
At first I thought that the $\ce{H}$…
Cargo
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3 answers
What is the meaning of the "dot" notation in chemical formulas?
For example for 4 given elements A,B,C,D, what's the meaning of $\text{AB} \cdot x \text{CD}$?
Sparkler
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27
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Can magnetic fields affect a chemical reaction?
This question was asked recently in an interview and I just said that "Yeah, like if the reaction involves ions or paramagnetic species". But the interviewer went on and asked me to elaborate on HOW will the reaction change, and I was stumped.
So…
najayaz
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What benefits do higher-rated NMR tubes provide?
You can buy NMR tubes in a huge variety of qualities, with an equally huge difference in price between the cheapest and the most expensive NMR tubes. They are usually rated for a specific spectrometer frequency, e.g. 300 MHz+ or 600 MHz+.
What is…
Mad Scientist
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27
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Pros and cons of Cartesian vs. Z-matrix representations of molecules?
Over the course of my studies, I have switched largely from using Z-matrix representations of molecular geometries in calculations to Cartesian representations.
The software that I use now makes it easy to add the sorts of…
Richard Terrett
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Why are the rare earths erbium (Er), terbium (Tb), yttrium (Y) and ytterbium (Yb) named like that?
I know the history of the discovery of the rare earth elements, that they were discovered near the village Ytterby in Sweden in the 19th century. Four elements are directly named after that village: erbium (Er), terbium (Tb), yttrium (Y) and…
Gimelist
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Anomalous boiling point of "iso-" alkanes
I was attempting to compare the boiling points of iso-hexane and 3-methylpentane.
Boiling points of organic compounds depend upon three factors according to Master Organic Chemistry – 3 Trends That Affect Boiling Points. They are:
The relative…
Safdar Faisal
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27
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2 answers
Why does diamond conduct heat better than graphite?
Our teachers made us accept (without any explanation) that diamond conducts heat better than graphite. What is the reason behind this (alleged) fact?
mepkn
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What's the difference between PBE and B3LYP methods?
I can't find an answer to that question. I was told that in B3LYP, more variables implemented in the method are empirical, but I can't find anywhere if it's true, and I'm sure it's not the only difference.
I'm new to calculations, and it seems so…
Basia
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Why do we still need to know about the Rankine temperature scale?
I am learning process principles in chemical engineering and I was taught various temperature units like Fahrenheit, Celsius, Kelvin, and Rankine. I see the first three being used quite commonly, but I rarely see the fourth being used. Where is the…
Pritt says Reinstate Monica
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