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
14
votes
3answers
4k views

Why is anhydrous copper(II) sulfate white while the pentahydrate is blue, even though both have one unpaired electron?

We all know that $\ce{CuSO4.5H2O}$ is blue and it turns to $\ce{CuSO4}$ on heating which is white. I also learnt about coordination complexes and d–d transitions and how transition metal compounds are ...
2
votes
1answer
73 views

What easily available chemicals do I use to turn oak light grey?

I have 10 square meters of dry and freshly sanded oak that I would like to artificially age/weather to the colour of the above photo. Once treated the oak is to be used for a bedroom interior. I was ...
1
vote
1answer
35 views

Which is a dye: Ferric Acetate or Ferrous Acetate?

I’ve been trying to make Iron Acetate to dye leather and I cannot, for the life of me, figure this out experimentally. I’ve been allowing steel wool to react with pure white vinegar in a sealed glass ...
5
votes
2answers
865 views

Considering the d-d transition how, does tetracyanidonickelate(II) ion exist as a colored complex?

As I refer on google, the resources indicated that, the d block elements which have unpaired electrons as in their ions, when they are making complexes with ligands, they can absorb different ...
3
votes
1answer
6k views

Explaining the colour change in the potassium permanganate titration of iron(II) ions

In the redox titration: $$\ce{MnO4- + 8 H+ + 5 Fe^2+ -> Mn^2+ + 4 H2O + 5 Fe^3+}$$ the colour change which occurs is purple to colourless, because of the decreased concentration of permanganate ...
0
votes
0answers
43 views

Why are sulphide salts of p and d block coloured?

I have studied that sulphide salts of s block are colourless while p and d block salts are coloured. But colour intensity of a salt is directly proportional to polarisation in salt. And s block ...
2
votes
2answers
28 views

Water color additive that will maintain color when water is a thin film

I'm producing thin sheets of liquid (50 to 100 microns) from a nozzle and trying to photograph them. I think it would help if I could color the water. However, typically as water becomes more of a ...
1
vote
2answers
62 views

Titrating iodine starch solution with sodium thiosulphate - Colour change

I investigated two mixtures with different solvents, one with water and one with n-heptane. Both contained iodine $\ce{I2}$ as a solute. To both solutions I added a bit of starch. As I remember this ...
0
votes
0answers
32 views

Measuring ions through color change during electrolysis

I have very little experience in chemistry, you might consider me a physicist, and I am mostly not even sure where to find the information I need. I will start off by describing my problem, I have a ...
1
vote
0answers
34 views

Why are polynuclear carbonyl complexes coloured?

We know that polynuclear carbonyls are colored and their intensity increases with increase in metal ions. But why does the color arise? I am aware that this is due to some transition between ...
1
vote
0answers
43 views

Why are Buckminsterfullerene (C60) solutions pink/purple?

A solution of Buckminsterfullerene $\ce{(C60)}$ is shown below: According to the April 8th Wikipedia page on Buckminsterfullerene $\ce{(C60)}$: Solutions of pure C60 have a deep purple color which ...
0
votes
1answer
35 views

Can a spectrometer be used to figure out spice ratios in a sauce?

There is a really good sauce that a local restaurant makes. I have had trouble recreating it, but have gotten somewhat close. I had the following idea: I could take an "image" of the sauce's color ...
3
votes
2answers
187 views

Is there a way to create natural Red food coloring from Turmeric in the house kitchen?

As a non chemist I have read in the Wikipedia article Curcumin that: Curcumin becomes bright red when it interacts electrostatically with phospholipid film. This text appeared without source ...
1
vote
0answers
28 views

Effect of optical isomerism on colour of transition metal complexes

I know that different stereoisomers of a given transition metal complex (cis- and trans- forms) have different colours. But do different optical isomers (non-superimposable mirror images) have ...
5
votes
1answer
2k 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?
14
votes
2answers
3k views

What happens to electrons in metal complexes after excitation by visible light?

My book writes: When white light shines through a solution of a complex ion of a transition metal, photons of a particular frequency are absorbed and their energy promotes an electron from lower ...
0
votes
0answers
34 views

Blue bottle experiment turning yellow after being left alone

I conducted the blue bottle experiment, mixing glucose, sodium hydroxide and methylene blue and shaking to produce a blue colour, which turns colourless after a while due to the reduction of methylene ...
4
votes
2answers
139 views

How to identify an emerald green solution with possibly two anions?

The solution is emerald green in colour. When added with water, it gives a pale blue solution. When reacted with $\ce{BaCl2}$, it gives a sky blue solution and a white precipitate. When reacted ...
0
votes
0answers
52 views

Looking for color changing reaction to track snow layer depth

I'm trying to find a chemical to mark the position of a snow layer with for detection in future seasons. The substance has to be: 1. Colorless 2. Not water soluble/solid 3. Stable for multiple years ...
1
vote
1answer
49 views

Some substances appear white when crushed while others do not. Why?

Calcite crystals are semi-transparent but turn white when crushed. I used to think that it has something to do with the scattering of all wavelengths of light from small particles. But that cannot be ...
2
votes
0answers
83 views

Colour of VO3^-?

To aquire the yellow colour of vanadium ion, it must be present in a 5+ oxdiation state. This can be acheived (according to my textbook) by adding dilute sulfuric acid to $\ce{NH4VO3}$, then followed ...
8
votes
3answers
12k views

What is the origin of the colour of azo dyes?

Is it the same reason as to why transition metal complexes have colour?
0
votes
1answer
137 views

Why is chromate coloured but tungstate colourless?

I have to try and work this out using the tetrahedral molecular orbital diagram for $\ce{[WO4]^2-}$ but I am confused as both are $\mathrm d^0$ right?
2
votes
2answers
299 views

Predicting colors of aqueous solutions

While going through my AP chem prep book again, I came across questions asking about the color of certain aqueous solutions. For example: Which of the following substances will produce a colorless ...
4
votes
1answer
1k views

Colored Flames Experiment

I am going to be doing a gender reveal for my sister's pregnancy. To do this, we wanted to light a huge fire pit and throw in a chemical to change the fire into the color (red/pink for girl, blue/...
2
votes
1answer
85 views

Why does the colour of the same compound (e.g. magnesium nitride) differ?

When I am searching the colour of $\ce{Mg3N2}$ I came across photos showing different colours: greenish-yellow on Wikimedia, and some other just yellow on some Google Images results. I am eager to ...
25
votes
4answers
3k views

How may copper acetate ligands be manipulated to change colors?

I have a solution of copper acetate and I would like to play around with the ligands to get different colors. Background: The copper acetate was made through mixing vinegar (5% acetic acid), $\ce{...
18
votes
0answers
3k views

Why is nitrogen dioxide (NO2) brown? [closed]

I don't understand why nitrogen dioxide $\ce{NO2}$ is coloured brown when nitrate $\ce{NO2-}$ and dinitrogen tetroxide $\ce{N2O4}$ are not. I understand it is due to absorption of light when its ...
2
votes
1answer
29 views

Predicting color of a TMB derivative affected by peroxidase

The ELISA test on HIV works by verifying the presence of peroxidase within samples. The verification process is done through the enzymatic reaction that said peroxidase has on TMB (3,3',5,5'-...
0
votes
1answer
3k views

How to Determine An Element's Colour

Different elements have different colours. Some elements may have similar colours like Sodium (Na) and Potassium (K), so that's why i'm asking "is there a way to calculate or even simply deduce the ...
18
votes
5answers
13k views

Iron chemistry: acetates for ebonizing wood

I have recently been “brewing” what is commonly called “iron acetate” for ebonizing wood, and I'd like to understand the chemistry of the iron/acetic acid reaction, which should be fairly simple, but ...
2
votes
0answers
63 views

What is the right color of calcium copper titanate?

I'm browsing Alibaba for calcium copper titanium oxide $\ce{CaCu3Ti4O12}$ (CCTO) and I find it variety of colors: pure brown, pale brown, reddish brown or grayish dark brown. Wikipedia does not tell ...
11
votes
4answers
2k views

Explanation for why nickel turns green in hydrochloric acid

My daughter has a chemistry test that I am helping her prepare for. One question is Nickel sulfate, $\ce{NiSO4(aq)}$ is a green solution. Nickel chloride, $\ce{NiCl2(aq)},$ is a yellow solution. If ...
1
vote
1answer
88 views

Does a complex that has no overall charge still have color?

The iron complex $\ce{[Fe(H2O)6]^2+}$ is colored but I'm wondering, if a pair of chloride ion is inserted on its secondary valency to form [FeCl2(H2O)6], does the complex loose its color or not?
2
votes
1answer
69 views

Why does the displacement reaction of zinc in copper(II) sulfate solution result in dark metallic copper?

It is commonly known that when zinc metal is placed in a solution of copper(II) sulfate, a displacement reaction occurs, and elemental copper is deposited onto the decomposing zinc metal. A practical ...
2
votes
1answer
104 views

What gives rise to the color of sapphires?

Here is what I know: Sapphires are composed primarily of $\ce{Al2O3}$ (in pure form colorless) as well as Fe and Ti (trace impurities responsible for the color). I know that the proportion and ...
0
votes
0answers
21 views

What solvents can solve aromatic urethane resins?

Do you have any information about chemical resistance of hexa-functional aromatic urethane acrylate? I want to know what solvents can solve aromatic urethane resins.
1
vote
0answers
36 views

Mixing ink with alcohol, MEG and water

First of all, I'm not a chemist and my knowledge in chemistry is not that extensive. However, I would like ask the following question: are there any chemical reasons that would explain that mixing a ...
4
votes
1answer
2k views

Is chromium the shiniest metal?

I have seen many pictures of chromium, and it's pretty lustrous as I must say. Here are some examples. Is it the most lustrous metal known? Edit: By lustre, I mean suppose if we have a mirror ...
0
votes
0answers
51 views

Does something like a fluorescent foil or a fluorescent film exist?

During my experiments I want the emitted laser beams to come back with a different wavelength than the original wavelength using a fluorescent foil or fluorescent film. The laser I'm currently using ...
13
votes
3answers
14k views

Why do s-block elements impart color to a flame?

Flame tests are a common way of identifying trace amounts of alkali metals (and to a lesser extent alkaline earth metals) in mixtures. Certain salts of $\ce{Ba, Sr}$ are also used in fireworks for ...
0
votes
0answers
26 views

Oxidation of Hexaaquachrom (II) with air

I had the reaction: $$\ce{Cr(H2O)6^3+ -> Cr(H2O)6^2+}$$ using $\ce{Zn}$ as a reducing agent. the colour turning from green to blue and I know that with contact with air the solution becomes ...
1
vote
0answers
41 views

Comparing the emission spectrum of ethanol and mixture of alcohols

Sorry if this question has a simple answer, but I've been unable to find it elsewhere. Using a diffraction grating, burning ethanol (99.9%) will produce a rainbow of colours. However, when burning ...
4
votes
0answers
1k views

Mechanism of DPD (N,N-diethyl-p-phenylenediamine) reaction with free chlorine

NOTE: As I've been finding new informations about the question, I've been editing the question to keep it up to date. If some comment doesn't make sense just check the Edit History. DPD (N,N-diethyl-...
1
vote
3answers
171 views

Is a hue indistinguishable from its equivalent frequency of light?

A hue is the color characteristic of a pigment, a particular chemical molecule, when illuminated by sunlight. Of course such a molecule will not emit a single frequency of light, but will emit a ...
2
votes
2answers
1k views

Does a calibration curve of absorbance vs concentration need to pass exactly through the origin?

If you are making a calibration curve for $\ce{CuSO4}$ where you plot absorbance against concentration and the curve deviates slightly from the origin, does it make the calibration curve useless?
1
vote
0answers
27 views

Two common fluids that don't mix inside a labyrinth [closed]

I'm not sure in which SE site put this question. Imagine a typical child toy, where a bunch of spheres move by gravity through a labyrinth. Now imagine a sealed small labyrinth with two fluids. I'd ...
3
votes
1answer
213 views

Why are most glow-in-the-dark things green?

I've noticed that many glow-in-the-dark objects you can purchase in the store are green. Occasionally I would come across something that was orange or blue, but mostly it seems that green is the ...
22
votes
1answer
11k views

What makes ABS plastic turn yellow?

If you owned old kitchen appliances or old computer you might notice that they the once cream white plastic become increasingly yellow, old and disgusting. I have read that UV lighting can damage ...
3
votes
1answer
1k views

Why did the solution turn green?

I mixed L Arginine with l Citrulline in Hibiscus and green tea water which was red in color. Once the red liquid hit the mix of powdered Aminoacids the solution changed green. Can someone tell me why? ...

1
2 3 4 5 6