Questions related to the colour and the reflecting and refracting properties of chemicals.

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Chiral compound

Among the four compound , there is one compound which is chiral compound . But according to me, all compounds should be chiral as all the compounds contain chiral carbon.
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Chiral molecules [on hold]

There are three compounds among these first and second are chiral as they have chiral carbon . But why the third compund is not a chiral compound and according to me it has two chiral carbon .
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28 views

Optical active compounds [on hold]

In the following compounds , how can we say that these are are optically inactive except the second compound . According to me they all the compounds do not have chiral carbon , then how can we say ...
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1answer
28 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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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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14 views

Does the thickness of the photoresist material change when exposed with UV light?

I am having problem in understanding whether the thickness of the material changes once it is exposed to the light. Especially, in photolithography field, once the material is spin coated on the ...
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1answer
59 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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23 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 ...
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1answer
156 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 ...
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56 views

Why does pH cause a change in the color of indicator solutions?

Why does pH actually cause an indicator to change in color? Obviously different indicators change colors at different pH's, as seen on the following page: https://en.wikipedia.org/wiki/PH_indicator ...
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1answer
45 views

Refractive properties of materials?

I've just read this article about meta-materials with 0-refractive index, which potentially may "permit" light with super-luminous rate /under rate is meant the propagation of light's phase, which ...
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1answer
84 views

Stereo chemistry, optical isomerism, meso isomers

How are meso isomers even isomers? By definition, meso isomers are compounds that are superposable on their mirror images, but doesn't that mean that the mirror image is just the same compound? Can ...
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1answer
79 views

Why some materials are transparent, but other ones aren't?

We have two materials; say glass and wood. Light passes through glass but it doesn't pass through wood. Is it caused by atoms and molecules arranged in glass and wood such that they interact ...
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1answer
91 views

How do we identify left handed and right handed crystals?

I was going through this article about how Louis Pasteur studied and explained the absence of optical activity in Racemic acid. Here's an extract: When Pasteur next examined crystals of the ...
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1answer
453 views

Why does Zinc sulphide glow?

Zinc sulphide is used in road signs because when light from cars hit the road signs, it glows. What actually is the reason for the glowing of road signs (actually glowing of $\ce{ZnS}$) ?
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24 views

What determines the color of a object? [duplicate]

Why is gold yellow for example? Which property of the atom determines the color?
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1answer
86 views

A compound that only absorbs UV-A radiation

As a similar idea to the question A compound that absorbs all visible light, I am curious if there is a compound (or compounds) that absorb UV-A radiation (shown below)? However, preferable the ...
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3answers
4k views

A compound that absorbs all visible light

Is there a compound that absorbs all visible light?
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1answer
101 views

What determines the elastic limit of a substance?

from what I know, the elastic limit of a substance is the maximum amount of stress/force/pressure (a bit of confusion on my behalf here) a substance can withstand and still return to its original ...
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1answer
330 views

Maximum observed optical rotation through a polarimeter

Is there a maximum optical rotation of plane polarized light that can be observed using a polarimeter? I understand that in a polarimeter, light passes through a filter that converts it into plane ...
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2answers
4k views

Are there non-transparent gases?

Are there gases that are not transparent at room temperature (i.e. at temperature below the point where the substance starts to radiate visible light due to heating)?
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1answer
105 views

Light scattering in sulfur colloids

Recently I did a reaction in the lab (the reaction itself is not important) whose product was colloidal sulfur. As I watched the sulfur particles form I noticed something strange: At first the sulfur ...
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1answer
97 views

Behaviour of element 111

Is element 111 considered to act as an eka-aurum? Being under the same column of group 11, which usually provides enough evidence for correlation of properties for an eka-element, would this element ...
2
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1answer
216 views

Thymol Blue - molar absorptivity

I did a lab about spectrophotometry and right now I need the molar absorptivity(ε) of thymol blue in acidic solution and also in basic solution. I have tried looking online but I haven't found the ...
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1answer
948 views

Are there any known chemical properties of tritium water that make it unusually different from protium water?

I suppose the first question supporting the main question is, has tritium water ever been synthesized in sufficient quantity to test chemical properties? If so, and apart from the obvious radioactive ...
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1answer
63 views

OD660 readings of yeast

I am working on a yeast fermentation project, and I am getting final OD660 reading of 1.85 for different media: yeast extracts+cane molasses, nitrogen source+cane molasses, and glucose+cane molasses ...
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1answer
57 views

dependence of Intensity on penetration of light

I want to know about a transparent material,In which penetration of light decreases as intensity of light increases.
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1answer
125 views

Reason behind Opaque translucent transparent

I would like to know the reason that some materials allow light to pass (transparent), blocks it a little (translucent), or completely reflects or absorbs it (opaque.) I'm don't have a PhD, so answer ...
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1answer
252 views

Does mercury fulminate really look like crystal methamphetamine?

In the AMC series Breaking Bad , Walter (aka Heisenberg) smuggles in a bag of mercury fulminate under the guise of crystal methamphetamine and threatens to blow the room up if he doesn't get his ...
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2answers
492 views

Is tetraammine dichloro cobalt (III) an optically active compound?

Is $$ \text{Co}[{(\text{N}{\text{H}}_{3})}_{4}{\text{Cl}}_{2}]$$ optically active? If so, write its stereo-isomers. I know that for a compound to be optically active, it should ...
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2answers
3k views

Why are there no cheap diamond equivalents?

We recently learned in school that diamonds sparkle as the are very optically dense, meaning that it takes longer for light to pass through them, thus meaning that the light totally internally ...
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39 views

What home chemical can I use to make droplet lens?

I'm very interested in making homemade droplet lens, I want to know what home element can I use to cook them. Here's a video showing the process, with no further information: ...
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1answer
200 views

Does inversion of configuration necessitate reversed optical rotation?

Say, optically pure 2-bromobutane undergoes $\mathrm{S_N2}$ reaction with an alkali to form 2-butanol. The configuration about chiral carbon will now be inverted, but is it necessary that the sign of ...
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1answer
41 views

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

I need to determine the purity of a solution and we need to discuss about the 'theoretical' refractive index of the substance that we are supposed to have.
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1answer
252 views

Why are square planar coordination compounds with four different ligands optically inactive?

Why square planar co- ordination compounds of type Mabcd do not show optical activity, although they contain 4 different ligands ( i.e. chiral central metal atom)
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1answer
3k views

Dextro,Levo rotatory and D/L Configuration

What does D(-) tartaric acid mean? D is always (+) Glyceraldehyde, therefore it should be +? If I am not wrong, the D indicates (+) Glyceraldehyde and L indicates (-) Glyceraldehyde and the (+) and ...
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2answers
322 views

Why do different impurities create different colors in diamonds?

Traces of nitrogen make diamonds yellow while traces of boron make them blue. What accounts for the differences in color for a given element?
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1answer
2k views

What is the color of elemental silver?

From my lab book it says it is black? I don't understand how we know the color of it is black. Can anyone explain?
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1answer
1k views

What are chiral environments?

I keep seeing the term cropping up, but cannot seem to find a definition for it. My understanding is that it is an environment in which, when the isomers interact with the environment, the two ...
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2answers
147 views

Effect of optical activity

I know that optical activity means polarisation of light but what is so special in that that it changes the properties of the substances significantly
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1answer
65 views

How does polarimetry account for the orientation of the molecules?

If you have some sample in solution (of a pure R substance), wouldn't the individual molecules all have a random orientation in space? Or do the photons emitted into the solution cause all of the ...
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1answer
593 views

What is there in this 3D representation of organic molecules I fail to grasp?

I think there's a basic idea I'm missing about 3 Dimensional representation of molecules. I think it may be about converting to Fischer representation. Consider the following two products of ...
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51 views

Liquid crystal structure: Equivalent effect of alkoxy group?

Consider a structure like this, R - Cy - Cy - Ph - OR' where Cy represents a cyclohexane ring, Ph is a phenyl ring, and R, OR' is alkyl group and oxygen bonded to different alkyl group. If 2 ...
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3answers
129 views

what is the simple enantiomer in the powder form that one can get?

I want to do some experiments on enantiomers. As it involves more calculations of potential energy surfaces, I would like to do this experiment on a simple enantiomer. For example CHBrClF. But this is ...
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1answer
185 views

Changes in defects in a material due to heat treatment

Currently i am doing some research on optical properties of a oxide material and for that purpose i have done some photoluminescence study on it. Because this is an ongoing research i cant divulge ...
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2answers
1k views

Why do only chiral molecules rotate the plane of polarized light and how do they rotate it?

I have learnt that only chiral or unsymmetrical molecules can rotate the plane of linearly polarized light. But, why is it so? And how can molecules rotate the plane or what does it actually mean by ...
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1answer
2k views

Can we predict Dextrorotatory and levorotatory character of an organic molecule?

Can we predict in which direction a given molecule will bend plane polarized light? If I have a molecule with R form in R-S nomenclature does it mean that the molecule will be dextrorotatory or is ...
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1answer
3k views

Finding chiral carbons in aromatic or cyclic compounds

I know that for a carbon to be chiral four different groups should be attached to that particular carbon. But, what about in the case of cyclic compounds? What's the method to check chirality if the ...
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1answer
111 views

Why does the Förster resonance energy transfer exhibit $\frac{1}{r^6}$ scaling?

The title more or less contains my question - why does the Förster resonance energy transfer (FRET) (photon?)-based energy transfer mechanism, which folks sometimes use as a spectroscopic ruler to ...
3
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1answer
701 views

Quantum dot band gap energy equation

I have been looking into certain approximations for band gap energies in quantum dots and have found this paper (Band-structure-corrected local density approximation study of semiconductor quantum ...