Questions where color (wavelengths associated with the visible region of the electromagnetic spectrum of about 400-800nm), or a color change is discussed.

learn more… | top users | synonyms

0
votes
0answers
27 views

Why lithium gives flame coloration?

Theoritically speaking, beryllium and magnesium does not give flame test because:- their atoms are comparatively smaller and the valance electrons are strongly attached to the nucleus. ...
4
votes
1answer
49 views

How potassium ferrocyanide is coloured?

The colour of a complex compound is due to unpaired electrons. As per crystal field theory, $\ce{K4[Fe(CN)6]}$ has no unpaired electrons so it has to be colourless. But then why is it coloured?
9
votes
2answers
351 views

Why is manganese(II) coloured although the transition should be spin-forbidden?

In every basic coordination chemistry class, at some early point the crystal field theory and LFSE will be taught, explaining that there will be an energy difference between d-orbitals (typically ...
3
votes
1answer
48 views

Why is MnSO4 colourless?

I get it that transition metal salts have colour due to d-d transition from $\mathrm{t_{2g}}$ to $\mathrm{e_g}$ orbitals in octahedral and the opposite in tetrahedral but why would $\ce{Mn^2+}$ not ...
0
votes
1answer
35 views

Why do colored solutions become more transparent as volume is decreased?

For instance, I was drinking Gatorade, and as I drank more and more, the drink became lighter in color. Why? I don't understand. I would think that the molarity stays constant and the color too. I ...
0
votes
0answers
30 views

What gives variations in the color of cadmium sulfide paint pigment?

Oil paint manufacturers sometimes make several "shades" of a color, all of which list the exact same chemical ingredient. For example, look at Gamblin's artist grade oils, in the yellow colors, ...
4
votes
1answer
55 views

What chemical properties that allow for colour exist in the dark?

Of course if there's no light around, there's no colour that you can see. On the other hand, the wall must have some property that makes it be blue. That property is still there in the dark. ...
0
votes
0answers
24 views

Special effects: using non-toxic solutions to create colors

I'm looking for a non-toxic solution to create low budget special effects without using digital effects. An actor ($175\: \mathrm{cm}$ tall) could: wear a particular kind of clothing? be coated ...
12
votes
1answer
905 views

Why/how is blood red? (colours of hemoglobin)

Oxyhaemoglobin is red, deoxyhaemoglobin is bluish-purple, and carboxyhaemoglobin is a cherry red colour. Evidently in the porphyrin around the iron molecule in heme there is a conjugated pi system ...
0
votes
0answers
11 views

Why do Aerozine and dinitrogen tetroxide burn with a colorless flame?

Here is a launch of the Titan II ICBM: (Image Source: Wikipedia) Wikipedia says: The Titan II also used storable propellants: Aerozine 50, which is a 1:1 mixture of hydrazine and unsymmetrical ...
7
votes
0answers
58 views

Allotropes of Phosphorus

Something I noticed whilst revising about Group 15 is, that the darker the allotrope of phosphorus, the more stable it is. White/yellow – very volatile, soluble, pyrophoric red – air ...
1
vote
0answers
36 views

How can methyl salicylate be found in 3 different colours? [closed]

Methyl salicylate can be colourless, yellow or red. What determines the colour changes?
1
vote
0answers
33 views

How do we see coordination complex colors?

The color of a coordination complex can be predicted using the Crystal Field Theory. The basic principle involved in this is that complexes absorb certain wavelengths of light and transmit the other ...
0
votes
0answers
28 views

What does a molecules color have to do with its bond/orbital energies?

For example, elemental iodine is deep violet. It's sigma bond or perhaps the lone pairs are capable of absorbing all visible light frequencies except violet which is why we see it as that color. ...
1
vote
0answers
48 views

Why is tin(IV) iodide bright orange while elemental iodine is violet?

Does it have anything to with iodines polarizability? Is there a way to explain this using sigma bonding or an MO diagram?
8
votes
2answers
149 views

Colour due to F-centre is same as that produced in a flame test, why?

I have noticed that the colours that the F-centres impart in Alkali metal halides are the same that the corresponding alkali metals impart to their flames. $\ce{NaCl}$ when heated in an atmosphere of ...
3
votes
2answers
50 views

Photosynthesis: Chlorophyll and color. [closed]

As I know, chlorophyll is green as it absorbs all wavelengths but green. It absorbs red, yellow, blue, purple, etc. Thus, the plant does not utilize green light. i] Why is chlorophyll green? Is ...
7
votes
1answer
89 views

What is the chemistry behind black colour of platinum black? [closed]

Platinum is a silvery white metal and is highly unreactive then why it's powdered form "platinum black" is black in colour?
7
votes
1answer
497 views

CuCl2 has colour but CuCl does not

$\ce{CuCl2}$ is green in colour while $\ce{CuCl}$ is white. What is the reason for this? Is it because the first compound exists as a complex ion and has d-d transitions?
2
votes
1answer
51 views

Color imparted to flame and color of coordination compounds

When we heat a ionic substance/compound, the ionic bond gets weakened and the metal is ionized. Is the color imparted to the flame due to absorption of light? i.e. Do we see the remaining wavelengths? ...
7
votes
0answers
125 views

Are there any colorful, odorless gases?

Gases are frequently described as "colorless, odorless, and tasteless." I am wondering if this is redundant, since I can't think of many gases that have a detectable color to begin with, much less ...
4
votes
1answer
97 views

How does complex ion differ from ligand complex?

As I understand, in terms of "colouring", ligand complex cause a transition metal cation centre's d-shell to split, allowing the electrons in that region to absorb specific frequencies of light, and ...
4
votes
1answer
118 views

Color of Anhydrous Transition Metal Salt

Why are some anhydrous transition metal salts colored? Here are some examples I found. Anhydrous cobalt(II) chloride ($\ce{CoCl2}$), with sky-blue color. Anhydrous chromium(III) chloride ...
5
votes
0answers
60 views

Increasing Covalent character increases Colour intensity

I observed some trends as follows:- $\ce{PbCl2}$ white and $\ce{PbI2}$ yellow $\ce{SnCl2}$ white, $\ce{SnCl4}$ red and $\ce{SnI4}$ black $\ce{AgCl}$ white, $\ce{AgI}$, $\ce{AgBr}$ and ...
8
votes
2answers
212 views

Why are acids usually depicted in fiction as green?

In cartoons, etc., acid is generally shown as vividly green, as in this scene from the Simpsons: We even have the colour "acid green". But when I used to use acids in chemistry class, they weren't ...
2
votes
4answers
103 views

Books showing colorful images of elementary particles…is this true? [closed]

Do electrons or protons or any other elementary particle have colors of their own or do they have smell?
0
votes
1answer
45 views

The color black [closed]

If a perfectly black object were present and it had a rough texture with bumps and crinkles, would it reflect any light? And can black reflect any light?
1
vote
1answer
137 views

Predicting color of precipitate

Is there any way of predicting whether a precipitate will be colored? I know that for solutions, transition metal ions with unfilled d-orbitals will have color because of d-orbital splitting in the ...
5
votes
1answer
66 views

why are simple organic molecules usually white?

I have heard that it is because they absorb electronically in the ultraviolet range, if this is true, why is it true. What is it about the nature of organic molecules that make them absorb in the ...
0
votes
0answers
25 views

How can you reduce Prussian blue without using liquid?

I have Prussian blue, iron(III) hexacyanoferrate(II), pigment suspended in oil, and I understand it is electrochromic; it changes from blue to colorless when Fe(III) is reduced to Fe(II). I've tried ...
1
vote
0answers
24 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, ...
2
votes
0answers
50 views

Why is silver chromate red?

Copper(II) ions are blue and chromate(VI) ions are yellow therefore copper(II) chromate(VI) would turn out to be green because it's a mixture of blue and yellow. In the same way, silver ions are ...
5
votes
0answers
20 views

What substances are typically used to produce cyan, magenta, and yellow ink?

Early in grade-school you learn blue, red, and yellow are the primary colors that can be used to produce any other color. If you're curious enough, you later learn the primary colors are actually ...
10
votes
2answers
205 views

What is the reason for the blue color of an ammoniated electron?

I am quoting a line from a book regarding reactivity of alkali metals with liquid ammonia. The blue colour of the solution is due to the ammoniated electron which absorbs energy in the visible ...
0
votes
0answers
19 views

Why does some copper (I) compound show color? [duplicate]

As far as I know, if the d orbital of a d-block element is fulfilled, then there is no way for electrons to change the orbital and show color. But some of Copper (I) compounds do show color. How is ...
-2
votes
1answer
112 views

What are the physical properties of the cation tris(ethylenediamine)cobalt(III)?

I am aware of the (pictured) structure of $\ce{[Co(en)3]^3+}$, but what are the physical properties of this ion? Namely, what is its colour?
3
votes
0answers
59 views

Do filter-specific dyes exist? Equivalently, do dye-specific filters exist?

Apologies if this isn't chemistry enough for chemistry.se. I'm happy to go elsewhere if there are suggestions. Blue + Red = Purple is arbitrary here. If any different colors might make this more ...
0
votes
0answers
20 views

Origin of different colour for thio analogue of indigo from blue to red

Why the thio analogue of indigo is red? What is the reason behind change of colour from indigo to red just by change of N to S. What I get is that there will be electronegativity, lone pair ...
0
votes
1answer
73 views

How to change color of water based on its acidity?

I recently saw a video on YouTube in which water, when mixed with a solution (I believe iodine was involved,) changed color based on its acidity. I am attempting to replicate this experiment, but ...
1
vote
0answers
53 views

Chemical reaction , blue to red and again to blue

I am trying to demonstrate color change in the liquid as it passes through a channel. I want the initial color of the liquid to be blue in color and as it passes and comes out of a small pipe , it ...
2
votes
0answers
59 views

Difference in color between the chromate and permanganate ions

As the title states, I'm wondering why the $\ce{[CrO4]^2-}$ and $\ce{[MnO4]-}$ ions display different colors in solution. Both of the metal ions have a $\mathrm{d}^0$ electron configuration, have the ...
-1
votes
0answers
19 views

what causes the colour change in oscillating reaction? how can i time each oscillation time as accurately as possible? [duplicate]

BZ oscillating reaction this reaction consists of: Potassium Bromate Malonic Acid and Potassium Bromide Cerium Ammonium Nitrate in Sulfuric Acid 0.50% Ferroin Solution I wanted to know where these ...
6
votes
1answer
440 views

How can the intense color of potassium permanganate be explained with molecular orbital theory?

In the permanganate ion, manganese is in the $+7$ oxidation state, therefore it is a $\ce{d^0}$ ion. $\ce{d^0}$ and $\ce{d^1^0}$ ions don't absorb visible spectrum radiation because there are no ...
0
votes
1answer
55 views

Why is urobilin yellow?

The yellow color of urine is due due a compound known as urochrome, or urobilin. Why is this chemical yellow? There isn't any coordination complexes. What else could cause this color? I have not ...
1
vote
1answer
55 views

Is there an agent that changes colour when exposed to air? [closed]

And if so, does it come in a liquid form? Thank you for your time
1
vote
1answer
25 views

Spectroscopy and Excitation of Electrons

As metals are heated, they glow white and then blue. How might you explain this change in color as the temperature of the metal is increased? My answer consist of the idea that with increased thermal ...
2
votes
0answers
38 views

Looking for an isomerization reaction that involves a color change for classroom demonstration purposes

I am in the process of designing a chemical kinetics course for undergraduates. I would like to demonstrate isomerization equilibria, and therefore am looking for a reaction A <-> B fulfilling the ...
1
vote
0answers
101 views

Predict flame test color?

If you know the composition of any sample of compound, is it possible to predict it's flame test color? For eg, if you can given Sodium Chloride, then without actually doing the flame test, can you ...
10
votes
1answer
150 views

Why is NO2 brown?

I have tried hard to find why $\ce{NO2}$ is coloured brown or why any of the coloured gases are coloured but I was not able to find out.
2
votes
2answers
164 views

Why does oxidized copper become green?

Why does oxidized copper turn green? I am sorry if this question is too basic, but am really stumped here. It would be helpful if one could provide a research paper or website with your answer.