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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1answer
27 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'-...
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0answers
50 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 ...
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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 ...
2
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1answer
59 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 ...
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20 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.
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29 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 ...
2
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1answer
100 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 ...
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1answer
86 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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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 ...
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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 ...
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0answers
34 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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476 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-...
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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 ...
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1answer
47 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 ...
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0answers
45 views

Is there any red dye that will work with perflurocarbons?

I have a perflourocarbon (PFC) that I am trying to dye a light red. Is there any way for this to be possible or a specific dye that works with the PFCs?
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1answer
165 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 ...
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48 views

Why does my rainwater turn yellow if I increase the pH to 7?

My rainwater is colourless when collected, but if I add a small amount of sodium hydroxide to increase the pH to about 7, after a few days it goes yellow. The colour change happens more quickly if I ...
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1answer
52 views

Why is the reason for color different in these two cases? [closed]

I have read in a book (NCERT India) about flame color for salts of alkali metal and color of transition metal complexes. In the first case, it says that during excitation of electrons to higher ...
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1answer
943 views

What exact color does ozone gas have?

This answer to a now closed question says that ozone gas has a "slight blue" color. But there are lots of blue colors: sky blue, ultramarine, phthalo blue, many others — what is closer to the color of ...
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1answer
786 views

How to determine the greatest d orbital splitting?

This question comes specifically from an IB Chemistry HL Paper 1 in May 2018 TZ1, namely question 8. Which complex has the greatest d orbital splitting? It gives 4 Complexes $\ce{[Fe(H_2O)_6]^{2+}}$,...
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Can factors such as non-chelating ions in solution or the temperature of solution change the d orbital splitting of complexes?

My currently primitive understanding of metal complexes is that the d orbital splitting depends on: Identity of central ion Charge density of ligand Geometry of complex ion oxidation number of ...
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0answers
35 views

Reduction of triphenylmethane dyes in ink

Right now I'm trying to explain why the ink from an ink pen turns colourless in water. I know that the pH is responsible as it breaks apart the conjugated system of double bonds. I'm just not sure on ...
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1answer
780 views

Potassium Manganate and Acidified Potassium Dichromate colour changes [closed]

I would be obliged if somebody could explain the colour changes for the reduction of potassium manganate and acidified potassium dichromate. I understand that for potassium manganate, it is being ...
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1answer
415 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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1answer
373 views

Colour of colloids

Why colours of colloidal solutions are different when viewed along different directions? For example Milk appears blue when viewed by reflected light and red when viewed by transmitted light Is it ...
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2answers
406 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?
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Blue color in the blue persian salt [duplicate]

Blue persian salt has tiny blue framgents. So far I could found two explanations: It is sylvinite mineral inclusions As said in Wikipedia, "The intriguing blue colour occurs during the forming of ...
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0answers
29 views

Metal colored flame and safety

For Chrismtas I was a given a wonderful gas lighter, that produced a pink flame by heating small metal pads (when the pads are cold, the flame is blue, once they are red hot, the flame is colored). ...
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2answers
271 views

What explains the stark white colour of my iodometric titration analyte solution?

During my Advanced Higher (secondary school) investigation, I reacted pure copper with concentrated nitric acid to acquire a copper nitrate solution. This was neutralised with excess sodium carbonate ...
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0answers
300 views

Why does LDA solution gradually turn dark brown?

LDA (lithium diisopropylamide) solution in THF/hexane gradually turns red-brown liquid. Especially commercially available one is extremely dark red-brown. What makes it brown? I've searched online ...
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0answers
68 views

Dilute FeCl3 colour is darker at 5e-4M than at 5e-3M. Why?

I did two different dilutions of $\ce{FeCl3}$ (within a $\pu{1h}$ timespan) from $\pu{0.05 M}$, and the one with $\pu{5E-4 M}$ concentration looked a darker orange than the one with $\pu{5E-3 M}$. ...
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1answer
262 views

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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0answers
39 views

Benzophenone Ketyl color origin

I was recently preparing the benzophenone ketyl radical by reacting it with sodium in toluene. Although this compound is really well known and it seems somewhat obvious and accepted in literature that ...
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1answer
1k views

Colour of platinum

Why does platinum have silvery shine whereas platinum black (finely powdered platinum) is black in colour although both have the same constitution of pure platinum? Due to similar composition, both ...
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3answers
141 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 ...
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1answer
46 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, ...
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0answers
35 views

What does “off-hue” constitute in the context of analyzing a sample using the Pt-Co color scale?

ASTM D1209, the method describing how to perform the Pt-Co color scale test for a sample, recommends reporting material that can't be matched to a particular standard as "off-hue". For color based ...
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0answers
37 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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2answers
667 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 ...
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1answer
1k views

Why does molten salt turn black?

Lately I have been seeing quite a few videos on YouTube about molten salt, specifically table salt (NaCl). One of the things that interests me about it is that regardless of what melting technique or ...
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0answers
96 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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3answers
6k views

What exactly is formed when K2Cr2O7 is reduced?

I read on Wikipedia and in many books that when $\ce{K2Cr2O7}$ is reduced, it forms $\ce{Cr^3+}$ and a change is noticed from orange color to green. I want to know in what exact complex/salt/compound $...
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0answers
105 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
5k 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 ...
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0answers
121 views

Green colour resulting from the formation of pi complex

Peter Sykes mentions in Guidebook to Mechanism in Organic Chemistry (6th ed.) on p.132 that there would significant differences in physical properties of the resultant mixture when we: React ...
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1answer
3k 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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1answer
230 views

Why does the gas from dry ice flow down?

I am reading Dan Broughton's answer in replying to the question "why does the gas from dry ice flow down" here. According to the answer, the fog is water's color and water is condensed and suspended ...
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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/...
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2answers
939 views

Producing sulphur dioxide for using in a reaction

I am doing an investigatory project on studying the coloured reactions of d-block and f-block elements. I have included two reactions that require sulphur dioxide as a part of my study. $$\ce{5SO2 ...
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2answers
3k views

Why is a [Cu(SCN)2] complex black?

I've been creating various Copper(II) complexes using different ligands and predicting their relative hues using Crystal Field Theory by using the spectrochemical series to predict the extent of d ...