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30 votes

Is there a commercial liquid with refractive index greater than two?

Taking the definition of refractive index $n = c/v$ into account, $n > 2$ means the velocity of light in the material $v$ is less than half than in vacuum $c,$ so there must be a strong interaction ...
C.X.F.'s user avatar
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21 votes
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How to think of solvated electrons?

The analogy with a proton is actually a good one if you are careful to remember that an electron is nearly 2000 times lighter than a proton. What does that mean? It means that despite the fact that an ...
jheindel's user avatar
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19 votes
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What is happening in this video of solvated electrons donated from sodium in ammonia?

I'll try an answer to this question because I watched this video a while back and did a bit of reading on it at the time and I think I understand the big picture. The problem is that these solvated ...
jheindel's user avatar
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19 votes
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Are there chiral compounds that don't rotate plane-polarized light?

Good question. There's a phenomenon named cryptochirality[1] (meaning “hidden chirality”), when a compound, though chiral, has practically unmeasurable optical rotation activity. It can happen to ...
mykhal's user avatar
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17 votes
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How is polarization of light measured?

The instrument used is called a polarimeter. You basically shine monochromatic linear polarized light through a solution of known concentration and you measure the rotation of the light on the other ...
DSVA's user avatar
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17 votes
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Difference between a "cartoon" flame test and a "real" flame test? How do chemists do flame tests correctly?

Your interest is greatly appreciated. As a first step, let's clarify that flame tests as an analytical tool are obsolete. No professional chemist will use them to identify a given unknown sample. ...
ACR's user avatar
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15 votes

Is there a commercial liquid with refractive index greater than two?

To complement @blu_potatos's answer, there are some other contenders having refractive index greater than 2 Arsenic di/trisulfide and sulfur and/or selenium and/or mercuric sulfide in arsenic ...
Nilay Ghosh's user avatar
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13 votes
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What is the difference between quantities reported as optical rotation and circular birefringence?

It gets very complicated, there are many papers and books on the topic and this little table, from Jensen et al. 1, gives a glimpse of the anisotropic effects: An extremely short answer is this: when ...
Ed V's user avatar
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13 votes

How is plane polarized light rotated by chiral compounds?

Circularly polarized light is like a helix that twists through space. The two components are mirror images of each other. Now, every molecule interacts with both the left-handed twisting light and the ...
Osal Thuduwage's user avatar
12 votes
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Effect of direct exposure to sunlight on various drugs

Conversion of D to L isomer or vice versa is about the last thing to worry about in this situation, even if it may be facilitated by sunlight to a significant extent (which I doubt). Also, storage of ...
Ivan Neretin's user avatar
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11 votes

Effect of direct exposure to sunlight on various drugs

Isomerism is only one (and probably a minor) pathway. Many substances have chromophores that absorb light. Absorption leads to a high energy intermediate that is more reactive and able to access ...
Zhe's user avatar
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11 votes

Is there a commercial liquid with refractive index greater than two?

Solutions of phosphorous in carbon disulfide are not only smelly and toxic, but they're hideously prone to catching fire. Methylene iodide is carcinogenic. Selenium and its compounds are toxic and ...
James Demers's user avatar
9 votes
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What happens when (+) 2-iodobutane is treated with NaI in acetone?

There is no equilibrium in the second reaction because the sodium bromide formed by the iodide displacement is not soluble in acetone so there is no Br- to displace iodide. In contrast with the first ...
Waylander's user avatar
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8 votes
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Can two lone pairs in different orbitals make a chiral centre?

Chirality refers only to the positions of the nuclei. So, if we have the situation you described where one Carbon is bonded to two other atoms (e.g. CX$_2$ or CXY) it can never be chiral. (i.e. a ...
PJ R's user avatar
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8 votes

How is 1,4,6-trichlorodiamantane optically inactive?

From this indeed Escheresque' screen photo, I assume the following molecular structure: which reveals to be and example of Note: There is a nice interactive symmetry gallery at Otterbein.edu, ...
Buttonwood's user avatar
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7 votes

Are all 'dextrorotatory' sugars in biology actually 'd' or '+' in chirality?

Dextrorotatory = d = (+). Levorotatory = l = (-). These terms describe the absolute sense of rotation in an optically active substance. D and L are older terms for the sense of chirality that can be ...
Zhe's user avatar
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6 votes
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Suggestions for 200-600 nm range transmitting polymers/materials

No plastic of any practically useful thickness$^\dagger$ has $80\%$ transparency down to $200~\mathrm{nm}$. Period. Below is a UV transmission chart for various materials from a marketing brochure ...
hBy2Py's user avatar
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6 votes

Is there a commercial liquid with refractive index greater than two?

In gemological testing of the refractive indices of gemstones, the upper limit of refractive index is $1.81,$ if a contact liquid is used in a conventional gemological refractometer. See, for example, ...
Ed V's user avatar
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6 votes

What is the difference between quantities reported as optical rotation and circular birefringence?

Ed V's answer above--which I am accepting--is correct and also allowed me to reach the conclusion on my own. I am just posting this because my confusion was not too hard to resolve once I saw the ...
daniel's user avatar
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6 votes
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How does Entropy influence the racemization of an optically active compound?

Where there is a mechanism to interconvert enantiomers, entropy will drive racemisation There is some context that is helpful but omitted from the question. Not all chiral compounds racemise under ...
matt_black's user avatar
5 votes
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When an electron returns to it's ground state does it release the same wavelength of light that promoted it in the first place?

Not necessarily... it can return to the ground state in multiple steps, releasing different wavelengths each time. Also, the excitation could be caused by something other than light in the first ...
iammax's user avatar
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5 votes
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D-Threose: reduction and optical activity

When you reduce the aldehyde (from the open chain threose, since the cycle cannot be reduced as it has only acetal-like functionality) you introduce a symmetry element (both ends of the molecule ...
James Dealon's user avatar
5 votes

Is the refractive index of a solution of four substances the median of the four substances' refractive index?

The answer by ron is quite correct, multiple methods exist for binary mixtures, as his reference details quite nicely. However, the question posed was for a mixture of four substances. I am unaware ...
user64780's user avatar
5 votes

How many stereoisomers can exist for 4,5-bis(3-hydroxyoct-1-en-1-yl)cyclopentane-1,3-diol?

The question is tricky, because the two ends of the wavy bond are both stereogenic units (chiral cyclopentane ring carbon atom, and the double bond), so there is some additional unintentional ...
mykhal's user avatar
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5 votes
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Why is FEP transparent and PTFE not?

Otherwise clear plastics lose their transparency from crystallization of the polymer. The crystalline phases have different refractive indices and when a sufficient number form the light becomes so ...
A.K.'s user avatar
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5 votes
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Would Z and E isomers show different optical activity?

Not necessarily. Although the change you suggest would not alter the absolute stereochemistry (S in both cases) of the asymmetric center starred, the two molecules are diastereomers and therefore will ...
Withnail's user avatar
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5 votes
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How to detect nM levels of Copper(I) Oxide in blood?

The main analytical problem in your case of detecting Cu(I) oxide in blood is that you do not know the fate of the particles once they enter blood stream. As I said earlier, Cu(I) is thermodynamically ...
ACR's user avatar
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5 votes
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Does syn-dihydroxylation form racemic mixture?

Oxidation of alkene to 1,2-syn-diol by cold basic $\ce{KMnO4}$ is a common classification test for alkene in undergraduate organic chemistry laboratory courses. OP had correctly recognized that this ...
Mathew Mahindaratne's user avatar
5 votes

Biocompatible, high refractive index medium for 780 nm?

First the refractive index of PEG varies by molecular weight and with time, as it gels. You might try using low-MW PEG, and letting it stand mixed with the YPD culture media. It is one of the most ...
DrMoishe Pippik's user avatar
4 votes
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Transparency and partially deuterated polymers

Deuteration lowers the vibrational frequencies C-H to C-D, but does not affect C-C etc vibrations. Thus some lowering of vibrational frequencies will make the ir region slightly more transparent by ...
porphyrin's user avatar
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