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.

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Will UVC light/ozone affects color on fabrics?

I'm planning to put a low power UVC light bulb into my wardrobe to kill bacteria and prevent bad smell on clothes but I'm wondering will it affect color on the clothes? I've done some research but ...
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4k views

Is chromium (III) green or violet in solution? [duplicate]

Is chromium (III) green or violet in solution? In terms of oxidation reactions between chromate and $\ce{Cr}$ (III) it forms a green color in solution, but when I searched online in different sources ...
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Plant Coloration Stabilizer

Question What chemical is used to stabilize berry juices used as wood stains? Aim & tries I am trying to make a stain for a snowboard design and coloration of the wood. I used pure pokeberry ...
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64 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 ...
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2answers
179 views

Egg-Detection in Pastries: An Analysis in Heat-Alterated Molecule Identification

I would like to know if anybody here knows of a method to detect the presence of ovalbumin--or any unique, egg-related molecule, in a baked good. Here I am anticipating that the "unique egg-related ...
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37 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 ...
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90 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?
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180 views

Transition Metals colours and electron absorbtion

I understand that when d-orbitals split some electrons can occupy the higher orbitals by absorbing frequencies of light, but do these electrons then fall back to their original ground states? If so, ...
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2k 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
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676 views

Fluoride Color Reaction

I am trying to find visual ways to demonstrate water contaminants. For example, chlorine reacts to N,N-diethyl-p-phenyldiamine (DPD), forming a magenta color. The chemical doesn't need to be accurate, ...
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42 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 ...
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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 ...
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33 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 ...
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37 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 ...
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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 ...
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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 ...
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45 views

When can colourimetry be used to determine the rate of reaction?

Can colourimetry be used if a coloured reactant react to give a coloured product? For example, in the reaction of reacting dichromate ions with oxalate ions in acidic environment, where dichormate ...
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131 views

Why does blood turn reddish brown?

Why does blood take on such a colour after a couple of hours? Is this the iron in my blood being oxidised to iron (III) oxide or is this something else? I have checked this article, and no I do not ...
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116 views

White compound, insoluble in water, turns pink and then white again on adding water

Which white, ionic compound(s) that is insoluble in water turns pink when you add only a little of water but white again when you add more water? I know that the cation is one of the following: $$\...
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1answer
732 views

Material that changes color when changing phase from solid to liquid [closed]

I was asked and am wondering myself, what are materials that change color when molten? I could not find any examples online, but it really interests me. I would to get some examples which have one ...
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660 views

Why do transition metals make colored compounds despite the remaining d orbitals being hybridized? [closed]

I know that transition metals make colored compounds when they forms a bond with a ligand, as the ligand increases the energy level of $\ce{d_{x^2-y^2}}$ and $\ce{d_{z^2}}$ orbital by repelling these ...
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127 views

How to rationalize the colour change of the thermochromic bis(diethyl-ammonium) tetrachloridocuprate(II) complex

The colour of the compound changes from deep green/green-blue to yellow upon raising the temperature. I'm trying to rationalise this by using the d-orbital splitting, but I've got myself in a logic ...
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35 views

How to safely change the color of a fire tornado?

So I've been watching a lot of fire tornado videos and I came across one that had a reasonable and safe setup (around the 3:23 mark): Fire Tornado DIY Is there a way to change the color of the fire ...
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138 views

How do colour pigments chemically work? [closed]

How do color pigments colour the plastics? Is there any chemical reaction, molecular association, or physical reaction? What kind of bonding mechanism is there between pigment molecules and plastics? ...
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58 views

Krazy Glue Color Change

A type of Krazy Glue changes from purple to clear when it dries. What is the chemistry behind the color change? Is it due to a particular compound only found in this particular Glue? A description of ...
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427 views

Why does acetic acid combined with dirt turn blue? [closed]

Around my faucet was some mysterious dirt from a previous tenant. I poured acetic acid with a concentration of 25 percent over it. I came back after a few hours and noticed some blue stains which hadn'...
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61 views

Coordination Chemistry: Predict colors (simple model, old)

I remember many years ago, when I prepared for a talk on coordination chemistry I found a PDF with a theory about how to predict the colors of simple coordination compounds. I remember the name of the ...
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213 views

Problem in Colour in Cerium (IV)Sulphate due to charge transfer

My text says that $\ce{Ce(SO4)2}$ is coloured due to charge transfer spectra. It also gives other examples such as $\ce{KMnO_4}$ and $\ce{K_2Cr_2O_7}$, to which I agree but when I read the conditions ...
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528 views

Ultramarine blue colour absorbing agent

Ultramarine blue ($\ce{Na2Al2SiO8 + Na2S}$, a sulfide-silicate complex containing sodium and aluminium) is insoluble when mixed in water and gives a blue color appearance to the water solution. Which ...
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113 views

Are there art supplies that create a new color by mixing through a chemical reaction?

When two elements or compounds react together, they form new compounds, which more often than not assume new colors. If the two elements or compounds don't react, they form uniform or non-uniform ...
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388 views

Material to change its color by temperature condition meets over time

There are thermochromic materials which their color changes reversible by temperature. Simply they show their current temperature by color. We can say their color is a function of current temperature: ...
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352 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, ...
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187 views

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

Does it have anything to with iodines polarizability? Is there a way to explain this using sigma bonding or an MO diagram?
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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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54 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 ...
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800 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 ...
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108 views

Why most excreta are brown?

This might sound funny but my friend asked me why most - if not every - faeces are of a brown or brownish color? Why not grey or slightly bluish or green for example? Is there any simple scientific ...
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38 views

Reason behind ZnO color [duplicate]

Why is zinc oxide yellow when hot and white when cold? Is it yellow because of the flame used to make it hot?
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378 views

why colour of CuSO4 and CuCl3 is different? [duplicate]

These two are simple ionic compounds , not complexes [if I do not consider water of hydration] then how can I rationalise the difference in colour?
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64 views

How to choose a colorant for a given substrate?

I know there are volumes of International Colour Index (homepage, wiki, paper), but I can't really extract from there for example what red colorants are compatible with both silk and polyester, etc. ...
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58 views

Yellow color solution after adding sulfuric acid to a molybdate (ammonium or sodic) solution [closed]

Adding sulphuric acid (6 mL) to a molybdate solution, either sodium (15g/1L) or ammonium molybdate (10.9g/1L), gives an stable transparent solution. It's been a while since I've been able to get that ...
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239 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 ...
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Does Nitrogen dioxide change colour if we put it in a constant temperature of e.g. 100 kelvin?

The changing of the colour of $\ce{NO2}$ is because of a change in temperature, resp. heating and cooling?
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What is the colour of chromium(III) chloride solution?

I had a question asking about the colour of the solution of chromium(III) chloride in my exam, all my colleagues have different answers, I couldn't find any exact answer after searching!
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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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887 views

Why does the colour of gold sol change with particle size? [duplicate]

Regarding the colour of gold sol, my book says Finest gold sol is red in colour; as the size of particles increases, it appears purple, then blue and finally golden. This is the image I found on ...
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156 views

Why does the addition of oxygen render materials colourless? [closed]

In our book, it is mentioned that $\ce{H2O2}$ (hydrogen peroxide) is used as a bleaching agent because of its oxidizing nature: \begin{align} \ce{H2O2 &-> H2O + [O]}\\ \ce{\text{coloured ...
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2answers
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How are electrons in conjugated molecules excited? [duplicate]

I have recently started reading about colour in organic molecules and come across conjugation of pi bonds. My question is pretty short... In transition metal ions I understand colour is caused by ...
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66 views

What is the main contributor of the color of honey?

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 ...
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49 views

Pigmentation of aromates [closed]

So, they try to color naftalene, nitrobenzeen and benzene. Only one of them colors. They can say with certainty that this is nitrobenzeen. Right/wrong and why? Sorry if my English isn't that great, ...