Questions tagged [optical-properties]
Questions related to color as well as the reflecting and refracting properties of chemicals.
130
questions
3
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2answers
108 views
Chirality and Optical activity
Do all chiral objects rotate the plane of polarization of EM waves? For example my hand is chiral, will it rotate the plane of polarization of EM waves of suitable wavelength?
0
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1answer
311 views
Which are the Geometrical isomers of the complex [Cr(NH3)2Cl2(en)]+?Is it one or two?
I was recently studying coordination compounds and i came across optical isomerism shown by complexes.I think that the complex i gave above have 4 geometrical isomers(I think this is where I am wrong, ...
1
vote
1answer
53 views
Are all 'dextrorotatory' sugars in biology actually 'd' or '+' in chirality?
When papers or articles say that all proteinogenic amino acids are 'levorotatory' or 'L', they often make a point of saying that only half of them are truly, optically levorotatory. All of them (...
1
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0answers
67 views
How to calculate the refractive index of mixtures?
In "How to Calculate the Refractive Index of a Formulation", the article outlines a method to find the refractive index of a mixture but the sources don't lead to any evidence regarding its ...
1
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0answers
30 views
Beer-Lambert law absorption by each species
Light travels length $l$ through a medium with $n$ independently absorbing species with extinction coefficients $\alpha_1,\dots,\alpha_n$. According to Beer-Lambert law, the amount of light absorbed ...
3
votes
0answers
167 views
Can a chiral molecule be optically inactive?
Does there exist a chiral compound with zero optical activity? It seems possible that for some (chiral) arrangement of atoms, the optical activity of one section of the molecule could be exactly ...
0
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1answer
107 views
Kinetics of inversion of cane sugar
Question 1
The formula for concentration of cane sugar as a function of time is given by
$$k = \left(\frac{2.303}{t}\right) \log\left[\frac{\alpha(0) - \alpha(\infty)}{\alpha(t) - \alpha(\infty)}\...
0
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0answers
26 views
What is the meaning of pi selectivity?
I came across this term while going through a research paper for the first time of organic chemistry on diastereoselectivity of tricyclo[2.1.0.02,5]pentan-3-ones. I am not familiar with the term and ...
10
votes
1answer
518 views
How is plane polarized light rotated by chiral compounds? [duplicate]
There are plenty of questions related to this topic on this site but no proper answer.
Can anyone please explain to me how plane polarized light is rotated by chiral compounds, and why it cannot be ...
1
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0answers
47 views
How to predict which type of optical isomerism [closed]
When I learnt about optical activity in school, my teacher told me that there is no way to theoritically predict whether a compound is dextrorotatory or leuvorotatory. How is that possible?
1
vote
2answers
542 views
How to check which compound will show optical isomerism?
So my teacher told that those compounds which have one or more chiral carbon present in them it will definitely show optical isomerism because it has an optically active stereoisomer, but there are ...
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votes
2answers
305 views
In the reaction mentioned what percentage of reaction proceeds via SN1 mechanism?
2-iodo butane (having radioactive iodine) reacts with KI (having non radioactive iodine). Rate of loss of optical activity was 1.96 times the rate of loss of radioactivity. What percentage of reaction ...
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votes
1answer
52 views
Optical activity of substituted biphenyl [closed]
How come the given compound in the diagram is optically inactive? The two rings should be in different planes due to steric hindrance between $\ce{COOH}$ and bromine. How am I wrong?
0
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0answers
27 views
How can randomly oriented molecules in a liquid solution create a certain polarization pattern (d or l)? [duplicate]
How can a large number of moving, randomly-oriented chiral molecules in a watery solution twist light only to the left or only to the right?
Wouldn't a levorotary molecule become dextrorotary if I ...
-1
votes
1answer
93 views
How is 1,4,6-trichlorodiamantane optically inactive? [closed]
How this compound is optically inactive I can't analyse any element of symmetry in this compound.
0
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0answers
88 views
Are centre of symmetry(COS) and alternate axis of symmetry(AAOS) dependent on each other?
COS=Centre of symmetery
AAOS=Alternate axis of symmetry
Lets suppose a molecule has a COS. Does it need to have AAOS?
What about the converse? If a molecule has AAOS does it necessarily have a COS?
...
12
votes
2answers
467 views
What is the difference between quantities reported as optical rotation and circular birefringence?
Optical activity gets complicated quickly and the following question is intended to avoid threshold confusion. The linked lecture note* seems very accessible to me and Table 10.6 in particular is ...
6
votes
1answer
123 views
Question about a line from Rosenfeld's paper on optical rotation
There are a lot of papers on optical rotation which cite Rosenfeld's (German) 1928 paper "Quantum mechanical theory of natural optical rotation..." [Quantenmechanische Theorie der naturlichen ...
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votes
1answer
102 views
Optical activity checking
In the following cyclopentane deratives, why can't I say that a,b,e have a center of symmetry so they are optically inactive and c as it has a plane of symmetry as shown is also optically inactive? ...
2
votes
1answer
92 views
The number of optical isomers of 3,4-dichlorobutan-2-ol
The number of optical isomers possible for the given organic molecule is?
$\ce{CH_3-C^*H(OH)-CHCl-CH_2Cl}$ (the configuration is fixed at $\ce{C^*}$)
The given answer is 2.
The carbon marked with an ...
-1
votes
1answer
89 views
Optical activity of cis-trans isomers of a co-ordination compound [closed]
Why do geometrical (cis and trans) isomers of [Pt(NH3)(Br)(Cl)(py)] not show optical activity ? Thanks In Advance...
1
vote
1answer
150 views
Is specific rotation defined for mixtures of enantiomers or meso compounds?
I recently had to do an experiment where we had to make a racemic mixture of D and L complexes and then resolve the enantiomers, and measure the optical rotation of the racemic mixture, and the ...
2
votes
0answers
59 views
Why upon melting of PEO between crossed polars colours appear?
Crystalline PEO when under crossed polars shows distinct Maltese cross pattern. Being birefringent, when polymer crystal align with the polarizer or analyser it shows extinction regions (effect known ...
0
votes
1answer
110 views
Which of the following isomers of 2,3‐dihydroxy‐4‐methoxy‐4‐oxobutanoic acid are identical?
Which of the following are identical?
A and B are identical
A and B are diastereomers
A and C are enantiomers
A and B are enantiomers
What I know is that when we rotate a Fisher projection by 180°, ...
3
votes
0answers
42 views
What gas would be suited best to form a density gradient in a long tube? [closed]
I want to set up an aero-optics experiment using a sealed ~5 m length of pipe with a gas inside. The gas must form a density gradient, and must be transparent enough to view a target at the other end ...
1
vote
1answer
41 views
When to permute two times to find optical configuration [closed]
I'm learning about S and R configuration, and I know that in case where the 4th substituant is not behind we should permute it with the one which is behind. then we find the new configuration and use ...
16
votes
6answers
6k views
Is there a commercial liquid with refractive index greater than n=2?
For an application I need a commercial, transparent liquid with refractive index $n>2$.
Is this kind of liquid available?
What's the chemical composition of this?
On the web, only $n=1.81$ is ...
1
vote
1answer
295 views
Conditions for molecular dissymmetry
In my textbook, under the topic "Asymmetric and Dissymmetric Compounds", the following statement is given:
A molecule which does not possess plane of symmetry, centre of symmetry, and alternating ...
2
votes
1answer
332 views
Is methanol optically active?
Strictly on theoretical basis, not based on experimental results.
I can very well be wrong, but I think that methanol should be
optically inactive because it has a plane of symmetry passing through ...
0
votes
2answers
60 views
Optical activity of (1r,3R,5S)-3,5-dimethyl-4-methylidenecyclohexan-1-ol
Could anyone explain why compound L is not optically active?
2
votes
1answer
39 views
Is there a relationship between loss of electrons and EM wave reflection? [closed]
Is there a relationship between the loss of electrons in a cation and the amount of electromagnetic spectrum, a compound of this cation would subsequently reflect or transmit?
For example, any ...
5
votes
0answers
131 views
What would superionic water ice look like?
Phys.org's Giant lasers crystallize water with shockwaves, revealing the atomic structure of superionic ice links to
Nature Physics: Experimental evidence for superionic water ice using shock ...
2
votes
1answer
142 views
How to detect nM levels of Copper(I) Oxide in blood?
I'm trying to design an experiment to detect nM quantities of Copper(I) Oxide in fish blood. Are there any specific tests for Copper(I) Oxide that can be used to detect trace quantities(~nM)? Any non-...
3
votes
0answers
28 views
A formula for the refractive index of a gas dependent on temperature and pressure
I am in search for a formula that gives me the refractive index of a gas at a given temperature and pressure. Does such a formula exist? Ideally the solution should have this form:
$n_g(t, p) = \...
3
votes
1answer
255 views
Would Z and E isomers show different optical activity?
Consider this compound, which is in E-configuration and that red asterisk denotes the chiral carbon. If I were to somehow cause the E-configuration of the alkene part to Z-configuration keeping the ...
2
votes
1answer
56 views
Synthetic ruby - damaged by heat less than its melting point?
A bit of a jewellery question but chemistry related. I want to encase a synthetic ruby (corundum, Al2O3) in silver by melting the silver around it. Either in a furnace or by casting. The MP of silver ...
1
vote
1answer
141 views
Optical activity [closed]
I was studying about the optical activity of compounds. And I found , it is written that the chirality of a molecule is the necessary and sufficient condition for a molecule to be optically active. I ...
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votes
2answers
1k views
Can we rotate a mirror image by any angle to check if it is superimposable? [closed]
A molecule is chiral when it is different from its mirror image, and achiral if it is identical to its mirror image. To check if the mirror image is identical to the original object, we have to check ...
1
vote
1answer
55 views
What is the refractive index of poly(methacrylamide)?
I've been looking for the index of refraction for poly(methacrylamide). I searched several vendors and in https://polymerdatabase.com/ with no success. Is there any database where I can find this ...
3
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0answers
54 views
How to align povidone-iodine molecules in order to look for optical polarization
In this answer I mention how early polarizing filters (e.g. sunglasses) were made by doping a polymer with iodine atoms and then stretching the film to orient the polymer molecules.
Electrons donated ...
6
votes
0answers
233 views
What compound has the strongest optical rotation of polarised light?
A question recently asked here whether compounds know to be chiral can have non-measurable optical rotations: Are there chiral compounds that don't rotate plane-polarized light?.
Apparently they ...
11
votes
1answer
948 views
Are there chiral compounds that don't rotate plane-polarized light?
I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit ...
5
votes
3answers
398 views
Can two lone pairs in different orbitals make a chiral centre?
Is it possible that if the two lone pairs in a molecule occupy different orbitals, then could this make the molecule chiral? What I mean is, suppose a carbon atom is attached to two different atoms ...
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votes
2answers
3k views
Why does 1,3-dichloropropane not show stereoisomerism?
It is a multiple choice question:
Which compound does not show stereoisomerism?
A 1,2-dichloroprop-1-ene
B 1,2-dichloropropane
C 1,3-dichloroprop-1-ene
D 1,3-dichloropropane
I can eliminate A and C ...
2
votes
1answer
4k views
What happens when (+) 2-iodobutane is treated with NaI in acetone?
After treating the compound with NaI, we should follow SN2 mechanism and the product will follow an optical inversion, giving us (-)2-iodobutane, but the answer is (±)2-iodobutane.
After going ...
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votes
1answer
2k views
How is Volume an Extensive Property? [closed]
Based on the following definitions, can anyone explain why volume is an extensive property?
Extensive Property: Properties that depend on the amount of matter in a sample.
Volume: the amount of ...
5
votes
2answers
1k views
Why is FEP transparent and PTFE not?
fluorinated ethylene propylene (FEP) is close relative of poly(tetra-fluoroethylene) (PTFE), both only contain fluorine and carbon atoms,both have very similiar properties yet FEP is relatively ...
12
votes
1answer
870 views
How is polarization of light measured?
Chiral molecules are classified as dextrorotatory (+) or levorotatory (-) depending on whether they rotate plane-polarized light (ppl) to the right or left.
My question is, how is such a measurement ...
2
votes
1answer
187 views
Does alumina become transparent at high temperatures?
Consider a normal opaque alumina crucible. I've heard that they become transparent at higher temperatures and therefore, are not appropriate for high precision DSC (caloric) measurements. The reason ...
2
votes
1answer
509 views
How many stereoisomers can exist for 4,5-bis(3-hydroxyoct-1-en-1-yl)cyclopentane-1,3-diol?
Q.10 For the given compound $\ce{X}$, the total number of optically active stereoisomers is ____.
This is from JEE Advanced 2018 second question paper.
I thought the answer to be at least 32 because ...
