Questions tagged [color]

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

Filter by
Sorted by
Tagged with
0 votes
0 answers
42 views

Why is AgOH brown when silver(I) ions are colorless?

As Wikipedia states, $\ce{Ag+}$ ions are colorless in solution: https://en.wikipedia.org/wiki/Color_of_chemicals Compounds that I know of containing $\ce{OH-}$ are also colorless or white (such as $\...
user avatar
  • 27
2 votes
1 answer
72 views

Does nitrous oxide decolorize potassium permanganate?

My teacher says that nitrous oxide can't form any complex with manganese in aqueous solution, so it can't be oxidised. However, shouldn't it get oxidised as it is present in the intermediate oxidation ...
user avatar
0 votes
1 answer
52 views

How can I produce Red Iron oxide with electrolysis

I am producing Iron Oxide with the intention of using it for pigmentation. My attempts so far have been to use electrolysis. My first attempt I used Borax as an electrolyte and a 12 volt adapter with ...
user avatar
4 votes
0 answers
89 views

Ferrocene's band gap is supposed to make it colorless but it isn't. Why is it so?

Wang and Islam [1] state that the ferrocene molecule's band gap, i.e. the HOMO-LUMO gap at the Kohn-Sham level, is 5.03 eV, which corresponds to an absorption wavelength of at most 240 nm. So, ...
user avatar
6 votes
2 answers
121 views

PVP-iodine and octenidine can stain skin purple, does the reaction create iodine radicals?

In this paper it is mentioned that ... octenidine can release iodine radicals from the PVP complex, resulting in a tissue irritation as well as strong brown to violet discolouration in the border ...
user avatar
7 votes
2 answers
229 views

Why is NMP developing a yellow color after distillation?

I got an aqueous mother liquor of N-methyl-2-pyrrolidone (NMP) from some reaction I was running and when I redistilled it under vacuum, it came out colorless but turned yellow the next day. I am ...
user avatar
3 votes
1 answer
110 views

Colour of diamagnetic compounds using Crystal Field Theory

I know that the colour in coordination compounds can be explained by CFT in terms of d-d transitions. Are d-d transitions possible in diamagnetic complexes? Why does $\ce{[Co(NH3)6]^3+}$ show colour? ...
user avatar
  • 86
0 votes
0 answers
19 views

Colorimetric titration of bisphenols: Liebermann's reaction?

I would like to titrate the content of bisphenols leeched in hot water from plastic bottles. I was thinking of a colorimetric titration using Lieberman's reaction, which detects phenols. Would the ...
user avatar
1 vote
1 answer
75 views

Why is instant coffee powder not as dark as the coffee resulting from it?

Instant coffee granules generally are of a light brown colour, while coffee made from it is a deep black. Pigments are far more concentrated in the dry form, to add water is to dilute them. Still, ...
user avatar
  • 415
0 votes
1 answer
39 views

Simple bistable and reversible electrochromic reaction in solution

I'm not a chemist and I'm looking for a simple bistable and reversible electrochemical reaction that changes color, specifically: A liquid in a glass with two electrodes that when a voltage is ...
user avatar
  • 11
3 votes
1 answer
156 views

Reaction between anilinium chloride with ferric chloride

I have a question about reaction between aniline and $\ce{FeCl3}$. I supposed that the following reaction proceeds with formation of brown precipitate: $$\ce{3C6H5NH2 + FeCl3 + 3H2O -> \underset{...
user avatar
7 votes
4 answers
311 views

When pigments absorb light only around a single particular wavelength, why aren't they still white?

I'm trying to understand how organic molecules get their colour. One major factor are conjugated double bonds which create delocalized pi-orbitals (e.g. https://en.wikipedia.org/wiki/...
user avatar
4 votes
0 answers
80 views

Briggs-Rauscher reaction doesn't oscillate and turns blue with Vitamin C

I tried to recreate the Briggs-Rauscher reaction by using a solution of $\ce{H2O2}$, $\ce{KIO3}$, $\ce{H2SO4}$, $\ce{CH2(COOH)2}$, $\ce{MnSO4}$ and a soluble starch. I used this recipe. In container ...
user avatar
-1 votes
1 answer
81 views

How can one change the color of Iron Oxide by changing the composition or hydration?

How does the color of rust change depending on its makeup and state, or more to the point, how would one put the rust into that state? For example, Wikipedia shows Iron(III) Oxide as being red in the ...
user avatar
  • 121
2 votes
0 answers
171 views

What causes the amber/colourless/blue colours in the Briggs-Rauscher oscillating reaction?

I am using this commonly cited but simplified reaction mechanism of the Briggs-Rauscher reaction. Reaction 1 & 2 occur simultaneously. For reaction 1, when the iodide concentration is low, the ...
user avatar
1 vote
0 answers
35 views

Are there any pathways that can change a solution to all colors of the rainbow?

The challenge's like this. Suppose you have a beaker containing a liquid of transparent or any color. You add some drops of another liquid and the beaker turns into, say, red after some swishing. You ...
user avatar
  • 355
1 vote
1 answer
107 views

How to predict colour of precipitate? [duplicate]

I am currently preparing for Junior science competitions and I am coming across many questions where colour of precipitate plays important role... Like When compound $\ce{Hg2(NO3)2}$ reacts with $\ce{...
user avatar
  • 233
0 votes
1 answer
233 views

Cobalt glass colour of potassium as

Question: Cobalt glass colour of potassium as: A) Crimson red B) Lilac C) Apple green D) Brick red I thought option B as true because on flame test, potassium gives lilac colour. But the given ...
user avatar
  • 1,416
3 votes
1 answer
424 views

What is the colour of cesium?

I am confused with the color of cesium. Some websites and books say that it is a silvery white metal, and some say it has a golden colour, and some say it has a silvery golden colour. Among these ...
user avatar
  • 1,416
5 votes
2 answers
526 views

What is the chemical composition of Ferrous Ferrocyanide?

To this day, iron-cyanide complexes confuses me. So, I want to settle this once and for all. After scavenging the internet, I gathered the following result: $$ \ce{Ferr} \color{blue}{\ce{ous}}~\ce{...
user avatar
  • 22.6k
1 vote
1 answer
48 views

What replaced lead-based pigments? [closed]

In the 1960s and before, even black and white letters had some lead from the actual metallic letters used by typesetters—some rubbed off. Same thing with books printed before 1970 or so and libraries ...
user avatar
  • 423
-2 votes
1 answer
97 views

Looking for gas or liquid for story research

I am working on a story for adaptation into animation. Main lead is a chemist in a traditional fantasy setting. The chemist uses her own compound to battle using fire or explosions. I love the ...
user avatar
0 votes
1 answer
140 views

Lithium Oxide Colour

According to Chemistry LibreText: Lithium is the lightest of all metals and is named from the Greek work for stone (lithos). It is the first member of the Alkali Metal family. It is less dense than ...
user avatar
  • 176
2 votes
1 answer
187 views

Ferrous chloride solution coming out purple rather than green?

I've got some steel wool in hydrochloric acid to attempt to make ferrous chloride and the whole solution has turned purple. From everything I've seen it's supposed to be green. I have no idea what's ...
user avatar
  • 31
-3 votes
1 answer
102 views

Nomenclature of Colors of precipitates and solutions

I have just started learning salt analysis in inorganic chemistry. In it i came across the names of colors of various precipitates and solutions. Why do they have prefixes such as "scarlet" ...
user avatar
0 votes
0 answers
285 views

Comparing intensity of colour in coordination compounds

I had given an examination recently in which the question asked was: Write the decreasing order for the intensity of color in $\ce{[CoCl4]^{2-}}$, $\ce{[Co(CN)4]^2-}$, $\ce{[Co(H2O)6]^2+}$ What my ...
user avatar
1 vote
1 answer
249 views

Why do boron salts impart a characteristic green colour to the flame

In salts of boron it exists as a cation in the B(III) form. It is known to impart green colour in several of its salts like borates, boron triflourides, boric acid etc. If there are no electrons in ...
user avatar
  • 1,359
1 vote
0 answers
43 views

How do I anodize bronze for thin film colors using electrolysis?

I am trying to change the color of the coins we have in Europe. I want to create patterns of certain colors. They are made from "nordic gold" (89% copper, 5% aluminum, 5% zinc, and 1% tin). ...
user avatar
  • 113
1 vote
0 answers
64 views

What caused a colour change when I mixed two different dish soaps?

I recently purchased "organic" dish soap refill made from saponified coconut oil and potassium soap (full ingredient list). Instead of waiting for the old dish soap (Dawn) to be completely ...
user avatar
  • 27
1 vote
1 answer
98 views

The color of resorcinol-formaldehyde resin

At school, I did an experiment of synthesizing resorcinol-formaldehyde resin. When I added $\ce{NaOH}$ and gave some heat, the color of resorcinol-formaldehyde resin inside the test tube became ...
user avatar
2 votes
0 answers
77 views

Is there a known value for the molar extinction (absorption) coefficient for amylose and amylopectin iodine complexes?

I am doing a colorimetry experiment with starch, and have a theoretical model based on Beer's law. To solve it, I need a known value for the molar extinction coefficients of amylose and amylopectin ...
user avatar
4 votes
1 answer
480 views

Flame Test of Alkali Metals and Alkaline Earth Metals

The flame test colors for alkali metal and alkaline earth metal salts are well known, but what about the metals themselves? Do they also give rise to the same colors (eg, brick red for Ca, pale green ...
user avatar
8 votes
2 answers
2k views

Why is bleaching with chlorine permanent but with sulphur dioxide temporary?

I was reading the properties of chlorine when I came across this statement: Chlorine is a powerful bleaching agent; bleaching action is due to oxidation. Chlorine bleaches vegetable or organic matter ...
user avatar
  • 121
0 votes
0 answers
34 views

What color would be produced by the burning of the listed chemicals of the projectile weapon the carcass?

The carcass was a projectile weapon developed by the French in the second half of the 17th Century. It was "named carcass because the circles which pass from one ring, or plate, to the other, ...
user avatar
  • 109
-2 votes
1 answer
118 views

Why is my dried out copper sulphate green when wetted with water?

I dried out some blue copper sulphate in an oven to see if it would turn white which it did. I can't remember exactly but I left it overnight in the oven at around 50 C. It was white the following day....
user avatar
  • 679
-3 votes
2 answers
97 views

The colors that we see [closed]

I have a question. When I was studying Coordination Compounds, I came across this para: When a sample absorbs light, what we see is the sum of remaining colors that strikes our eyes. Observed and ...
user avatar
  • 23
0 votes
2 answers
257 views

why do we see characteristic colors of alkali metals in oxidizing flame?

I am a high school student and I am a little confused in a topic, My confusion is that: We know alkali metals and their salts imparts characteristic color in oxidizing flame, for example: Lithium ...
user avatar
4 votes
0 answers
209 views

Why does my drierite turn bright bright blue, instead of pink?

Drierite a brand name of a commonly-used, calcium sulfate-based dessicant in many chemistry labs. The lab I work in has a dessicator box we use to store hygroscopic materials. It isn't a a true dry ...
user avatar
  • 20.3k
1 vote
1 answer
195 views

Why is HBr colorless while Br2 isn't?

Bromine ($\ce{Br2}$) has a dark reddish color. If it reacts with something like benzene, this results in the formation of Bromobenzene and $\ce{HBr}$: $$\ce{Br2 + C6H6 ->[{Cat.}]C6H5Br + HBr}$$ It ...
user avatar
  • 253
-1 votes
1 answer
1k views

Why is HgI2 a colored complex?

Why is $\ce{HgI2}$ a colored complex it has fully filled d-orbits. According to the book, one which has fully filled d-orbital has no color in transition elements. So, why is this compound colored?
user avatar
7 votes
1 answer
215 views

Analysis of cations using sodium thiosulphate

A question in an exam was as follows:[1] How many of the following salts are first soluble in $\ce{Na2S2O3}$ solution, followed by the formation of a white precipitate and finally the precipitate ...
user avatar
0 votes
0 answers
238 views

What characterises the smell of alkane hydrocarbons?

I have heard that aromatic hydrocarbons smell fruity and like petrol. However, I understand that there is a class of hydrocarbons called alkane, as for example propane or butane. I wondered if I might ...
user avatar
5 votes
1 answer
354 views

Why did ammonium chloride fumes turned pink in this synthesis?

I was watching the synthesis of tetrasulfur tetranitride performed by Tom on his Youtube channel, Explosion & fire. He followed the basic route: adding ammonia gas to sulfur chlorides ($\ce{SCl2}$ ...
user avatar
  • 22.6k
0 votes
1 answer
56 views

Actual color of colloids [closed]

I have read that the color of colloid depends upon the wavelength of light scattered by the dispersed phase and also in the sense in which the receiver receives the light. If all of this depends on ...
user avatar
  • 23
1 vote
1 answer
139 views

Why aren't solid pure transition metals colourful?

I understand that the compounds of transition metal are colourful because of the appropriate energy gap between different d orbitals. But why aren't they also colourful in their solid pure state? For ...
user avatar
  • 765
-3 votes
2 answers
177 views

Controlled burn with colored flames (Gender Reveal) [closed]

Is there a single solvent that can dissolve chemicals/elements that when burned, will produce the color of its respective chemical/element? If so, what chemical/element can be dissolved in this ...
user avatar
2 votes
2 answers
435 views

The color of the most sulfides of p- and d-block elements

My teacher said that many of the sulfides of d-block and p-block are black. Why?
user avatar
  • 1,345
0 votes
1 answer
154 views

What is the main contributor of the color of honey? [closed]

I was told that the color of honey contains so much chemistry and that was interesting to me and after doing a couple of research I found that the color of honey depends on the presence of plant ...
user avatar
3 votes
4 answers
1k views

Chemical elements or compounds with yellowish white color [closed]

Are there chemical elements or compounds that have a yellowish white (cream) color in their natural state?
user avatar
  • 183
1 vote
1 answer
224 views

Colour due to transmission and reflection

It makes sense to me that when looking through a sample (observer | sample | light), it should appear as the opposite of the light absorbed, but it does not make sense to me to expect the same when ...
user avatar
  • 116

1
2 3 4 5
7