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Questions tagged [optical-properties]

Questions related to color as well as the reflecting and refracting properties of chemicals.

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1answer
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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 ...
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1answer
20 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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2answers
370 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 ...
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1answer
37 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 ...
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0answers
30 views

Aligning 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 ...
5
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0answers
100 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 ...
6
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1answer
502 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
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3answers
189 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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2answers
269 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 ...
2
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1answer
845 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 ...
-1
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1answer
368 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 ...
3
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2answers
318 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 ...
11
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1answer
840 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 ...
3
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1answer
95 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
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1answer
92 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 ...
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2answers
232 views

Meso and achiral does both term means the same?

When a molecule has plane of symmetry, or centre of symmetry it is termed as an achiral compound (though it contain some chiral centres). Same goes for the meso compounds due to the internal ...
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3answers
101 views

When an electron returns to it's ground state does it release the same wavelength of light that promoted it in the first place?

If this is true, I fail to understand why we see colour at all -- wouldn't any wavelengths absorbed by electron promotion be inconsequential to colour because there would an equal amount, and ...
0
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1answer
61 views

What does it mean if I am unable to write RS configuration for a compound?

We had to write all possible optically active monochloro derivatives of 2-methylbutane. I was unable to write RS configurations for 1 and 3, since they have carbon atoms with more than one same groups ...
2
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1answer
51 views

Intensity of “surface plasmon resonance “ absorption peaks for a nano-rod

The SPR absorption spectrum of a nano-rod is seen to have two peaks with the longer wavelength peak corresponding to the absorption by the longitudinal plasmons and the other to the transverse ...
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0answers
40 views

Is it possible to have a fully opaque 'switch glass'?

Current switch glass (smart glass) technology permits for a transparent glass to become semi-transparent, i.e., translucent. For my application, I was wondering if it was possible to make a 'smart ...
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1answer
596 views

Conditions for Chirality in optical isomerism [duplicate]

Is it necessary that any atoms which is chiral must have 4 different atoms around the central chiral atom(maybe it can be carbon if it's organic molecule) bonded to it? More specifically: I mean can't ...
6
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2answers
918 views

Effect of direct exposure to sunlight on various drugs

Today, we were discussing optical activity in class and our teacher said that some drugs are kept in dark coloured bottles to avoid direct exposure to sunlight. Same is the case with some other drugs ...
0
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1answer
336 views

Refractive index of barium sulfate

What is the refractive index of barium respectively where do I find it? I only find values for alpha, beta and x-ray radiation like on https://pubchem.ncbi.nlm.nih.gov/compound/barium_sulfate#section=...
5
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1answer
93 views

Optical techniques for kinetics studies

What optical methods can be used to measure the concentration of reacting gases in a reactor during an exothermic and fast reaction? I need to monitor and measure the local concentration of my gases (...
22
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1answer
684 views

How to think of solvated electrons?

This excellent answer explains at length what's happening in this fascinating video entitled Liquid Electrons - Periodic Table of Videos. In the screenshot below, the metallic-looking solvated ...
5
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1answer
166 views

How do I run MP2 and/or CCSD-level hyperpolarizability calculations with GAMESS?

I have used GAMESS before for TDHF (RPA) / TDDFT level first hyperpolarizability ($\beta$) calculations. However, I cannot figure out how to calculate $\beta$ with MP2 and CCSD for comparative ...
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1answer
209 views

How do chemical bonds increase molecular refractivity?

I see that the molecular refractivity of a compound consists of the refractivity indexes of its composite atoms and chemical bonds, and that the refractive index $n$ of a substance increases with its ...
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2answers
107 views

Permanent cloudy colloid with water

I need to make a cloudy white liquid where the particles won't eventually settle out. It will be exhibiting the Tyndall effect for a very long time. I'd use milk, but I don't want it to become rancid....
6
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1answer
289 views

D-Threose: reduction and optical activity

I've bumped into this exercise: Judging by the mechanism of reaction between D-threose and $\ce{NaBH4}$, do you think the final product will be optically active? To me looks like a reduction, ...
4
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1answer
59 views

Finding a substance which has a continuous gradient in refractive index

I need to find a substance whose refractive index is constantly changing and directly proportional to the square root of the depth. I know I'm looking for a lot, but I'd really appreciate any ideas or ...
5
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0answers
38 views

Is there any molecule describable by three-level with mixed parity and transition dipole moments in different directions?

I would like to know if there are molecules described by a three-level system with mixed parity and transition dipole moments in different directions. By mixed parity I mean all three transitions can ...
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1answer
798 views

What is happening in this video of solvated electrons donated from sodium in ammonia?

I just saw the Periodic Video Liquid Electrons - Periodic Table of Videos where sodium is added to liquid ammonia. The demonstration shows that even if electrons are solvated, if you have a high ...
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0answers
887 views

Home science optical absorption test for approximate caffeine quantity in coffee?

I started with How can you measure the caffeine content of a liquid at home? in the cooking stackexchange, but the test strips were only qualitative (yes/no) and don't seem to exist anymore, and the ...
8
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1answer
217 views

Discovery of optical activity of enantiomers - where did the idea of using polarized light came from?

According to Wikipedia, optical activity was first observed in 1811 in quartz. Louis Pasteur's contribution is also mentioned there and in other sources as a major advancement in establishing optical ...
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1answer
181 views

Optical activity of starch

I found this beautiful picture of starch granules in this German Wikipedia article about optical activity. Unfortunately, I have no idea what am I looking at. What are these crosses and why are they ...
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0answers
43 views

Is optical activity of a given compound a statistical picture?

When optical activity is taught it is done in terms of single molecules. But when it is actually measured it is done on a large collection of such molecules. So, how does the asymmetry manifest itself ...
3
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1answer
133 views

Suggestions for 200-600 nm range transmitting polymers/materials

I am a student of physics who is doing research related to Cherenkov measurements. For that purpose, I need suggestions for some materials that have the following properties: $80\%$ transparency in ...
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2answers
4k views

UV-Transparent Plastic?

I am looking for a type of plastic, preferably in the form of a sheet or film, that is weatherproof, durable, flexible, and both transparent and UV-transparent. Most films I've seen so far are treated ...
3
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1answer
108 views

Transparency and partially deuterated polymers

I've been skimming over the literature and have come into some conflicting information about the optical properties of partially deuterated polymers. From what I've seen, in general deuterated ...
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2answers
422 views

Can a system of 2 consecutive Biphenyl systems be optically active , even if any adjacent biphenyl systems arent optically active?

This question came in an online test, where they asked whether or not 22,26-dibromo-12,32-dichloro-23,25-diiodo-16,36-dimethyl-11,21:24,31-terphenyl was optically active. (The answer is that it is ...
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0answers
106 views

Calculating Optical Absorption Spectra using Ab Initio Computations

My main question is, How does one compute the optical absorption spectra of a molecule by using say, Configuration Interaction energy and associated transition dipole moments. I am trying to use an ...
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2answers
3k views

Can diastereomers form a racemic mixture?

In my book, it says racemic mixture is the mixture of + and - optical isomers and it is optically inactive. This means enantiomers (optical isomers which are mirror images to each other) can form ...
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0answers
88 views

Approximate magnetic susceptibility of these liquid propellants?

This question asks if the comparatively large paramagnetic susceptibility of liquid oxygen (LOX) is considered when designing rocket tank and engine systems. This comment suggests fuels such as RP-1 (...
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1answer
84 views

optical rotation of styrene oxide

Which optical isomer of Styrene Oxide would be produced if it is synthesized via epoxidation of the halohydrin. i.e. Is there a way to deduce this? I assume it would depend on which isomer the ...
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1answer
786 views

Isomers of coordination compounds

Does [Pt(CH3-CH(NH2)(COO-))2] show geometrical and optical isomerism? According to me Pt should be dsp2 hybridised giving a square planar geometry. So it is of the form M(aa)2 type. The ligand ...
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2answers
83 views

Why are fats glossy?

I am talking about the standard fats we see in everyday use (triglycerides). It seems that no matter what the composition, saturated or unsaturated, all fats are glossy when liquid. I don't know if ...
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0answers
29 views

Why are certain substances clear/invisible? Can we create invisible objects? [duplicate]

This is more so a question of how light interacts with matter. For example, why are substances like oxygen generally invisible? If the light hitting the molecules were absorbed, it would appear black, ...
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1answer
1k views

A substance that is immisiscible with water and that can be made cloudy

I need to identify a substance that is immiscible with water that is or can be made cloudy. At the moment I'm using glycerol, but I don't know how to make glycerol cloudy nor is it perfectly ...
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0answers
40 views

What is the reason behind optically activity of compounds [duplicate]

I am currently being taught optical activity of compounds and I had this question: Optical rotation (optical activity) is the turning of the plane of linearly polarized light about the direction of ...
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1answer
236 views

What kind of optical activity requires chirality?

From "Meso compound" in Wikipedia: A meso compound or meso isomer is a non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite ...