83
votes
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Is it true that heavy water is not blue?
Based on your description, I may have found the article you originally saw, or at least one very similar.
Researchers from Dartmouth College published a paper$\mathrm{^1}$ in which they report, among ...
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69
votes
Is it true that heavy water is not blue?
This does seem to be the case. I don't have images of the different types of water, but I did find this overlaid IR-visible spectrum of water and heavy water:
As you stated, the presence of deuterium ...
- 11.5k
33
votes
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Why is snow white?
The difference between snow and ordinary ice cubes is mainly about the size of the particles. Snow is made from small, irregular crystals with many edges at a very small scale. Light is refracted or ...
- 34.3k
27
votes
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What makes ABS plastic turn yellow?
What you're specifically describing is typically known as UV degradation. The color change is due to the oxidation of the polymers that make up the plastic. These chemical reactions are demonstrated ...
- 508
26
votes
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Soaps come in different colors, but why is soap lather always white?
Though @DHMO's answer is quite interesting, you shouldn't take it without a pinch of salt. I've to disagree with it in some aspects.
Soap colorants range from various kinds of Mica to dyes found ...
- 18.3k
26
votes
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What gives fresh milk a yellow tinge?
The main substances that cause the yellowish color of the milk are carotenoids [1]. The main carotene involved is the beta-carotene coming from the feed that cows eat.
Some studies have been carried ...
- 8,969
25
votes
Can flames be colored black?
This video shows how a black flame is achieved. If you illuminate the fire with a monochromatic light source (sodium vapor lamp) and introduce a species in the fire that absorbs that wavelength (...
- 301
24
votes
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Why do transition elements make colored compounds?
You are absolutely correct, it all about the metal's electrons and also about their d orbitals.
Transition elements are usually characterised by having d orbitals. Now when the metal is not bonded ...
- 7,254
23
votes
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What causes the iridescent colour in laboratory grown bismuth?
The colour is from a thin film of bismuth(III) oxide that forms on the surface if the crystals are formed in air. At the elevated temperatures used to melt bismuth, the oxide forms quite quickly. The ...
- 12.7k
23
votes
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Why is manganese(II) coloured although the transition should be spin-forbidden?
Selection rules
The intensity of the transition from a state $\mathrm{i}$ to a state $\mathrm{f}$ is governed by the transition dipole moment $\mu_{\mathrm{fi}}$ (strictly, it is proportional to $|\...
- 69.6k
22
votes
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What exact color does ozone gas have?
Due to Chappuis absorption, ozone does have a bluish color. To determine exactly what kind of blue it is, let's first look at the spectrum of absorption in the Chappuis band. The following plot was ...
- 975
21
votes
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Explanation for why nickel turns green in hydrochloric acid
The question is really badly worded. For starters, let’s look at solutions of nickel(II):
Figure 1: Nickel(II) solutions. From left to right: $\ce{[Ni(NH3)6]^2+}$, $\ce{[Ni(en)3]^2+}$, $\ce{[NiCl4]^2-...
- 66k
20
votes
Accepted
Are there colorful metals besides gold and copper?
Osmium has a bluish-gray tint.
Well; slightly.
Cesium is silvery-golden!,
But don't wear it.
- 2,187
19
votes
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How can the intense color of potassium permanganate be explained with molecular orbital theory?
Let’s take a look at a qualitative MO scheme for a tetrahedric transition metal complex whose ligands have three p-type orbitals each. On the left of figure 1 you have the metal orbitals ($\mathrm{3d}$...
- 66k
17
votes
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Color changes of a solution of acetone and sodium hydroxide
Under basic condtions, acetone does condense with itself, first to form mesityl oxide, which is colorless, and then to form isophorone, which has a yellow color.
Both mesityl oxide and isophorone are ...
- 21.4k
17
votes
Soaps come in different colors, but why is soap lather always white?
You might have observed that large soap bubbles are transparent.
This is because the color has been diluted to a great extent that it basically became transparent.
Now, the foam is just a multitude ...
- 4,925
17
votes
Accepted
Colour of platinum
In bulk metals, electrons in the conduction band are shared, creating a "sea" of reflective electrons. A nanoparticle, though, is so small that there is no conduction "band", just discrete levels ...
- 26.6k
16
votes
Accepted
Why/how is blood red? (colours of hemoglobin)
The $\ce{Fe}$-porphyrin complex is a vastly conjugated $\pi$-system, in which the oxidation state of the $\ce{Fe}$ plays a central role. The wavelength of light absorbed by hemoglobin exactly ...
- 23.7k
16
votes
Accepted
What gives milk its characteristic white color?
There is no "pigment" that makes milk white.
According to Wikipedia:
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective ...
- 18.3k
14
votes
Why are acids usually depicted in fiction as green?
The green is the color of bile which usually accompanies gastric acid. Acid in its original context referred to a bitter taste. Bitter tasting compounds, such as vinegar, is what led to the modern ...
- 2,214
14
votes
Why is anhydrous copper(II) sulfate white while the pentahydrate is blue, even though both have one unpaired electron?
Although the question is a bit old, I think it still hasn't been answered yet. And by looking at the given answers it seems like the discussion went into a different direction at some point.
So let's ...
- 4,182
13
votes
Are there colorful metals besides gold and copper?
There is no element other than gold and copper with similar colors; see http://periodictable.com/Properties/A/Color.html.
There are many metal alloys that are red and golden, such as phosphor bronze,...
- 26.6k
13
votes
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CuCl2 has colour but CuCl does not
The reason is indeed $\text d$-to-$\text d$ transitions. The d orbitals of both $\ce{CuCl}$ and $\ce{CuCl2}$ have two possible energy levels (based on crystal field theory).
$\ce{Cu(II)}$ is a $\text{...
- 3,265
13
votes
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Is chromium the shiniest metal?
You likely refer to remission, especially if you would collect spectroscopic data with an integration sphere at hand. More generally, you refer to reflectance, which depends on the material, the ...
- 26k
12
votes
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Why is there a difference in the colours of K₂Cr₂O₇ and K₂CrO₄?
I'm really excited for this because I get to reference the almighty color wheel!! Fair warning, this answer is much more qualitative than quantitative, but that's more interesting sometimes anyways.
...
- 12.8k
12
votes
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Why do s-block elements impart color to a flame?
All elements colour the flame somehow. The salt that is held into the flame dissociates homogenously (i.e. you’re not creating unpaired ions but rather single metal atoms and their counter-radicals), ...
- 66k
12
votes
Accepted
Why are the plastic balls used to reduce evaporation in this reservoir black instead of white?
This piece in Bloomberg News is about Sydney Chase, the founder of XavierC, the company which makes the "shade balls" in question (there are two other suppliers, Orange Products, Inc. and Artisan ...
- 10.5k
12
votes
What is the reason for the blue color of an ammoniated electron?
Both of your questions could benefit from more background, so please forgive me if I understood something wrong. However, I'll try to answer as best I can:
The excess electron in liquid ammonia is ...
- 544
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