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?
1 Answer
Here is the reflectance spectrum for silver
It reflects the entire visible spectrum, absorbing light only in the ultra-violet region. An ingot of elemental silver will have a silvery-white color. In fact silver is said to be the "whitest" of all metals. If you grind the silver up into smaller and smaller particles, the silver will appear progressively grayer or darker. This is because smaller particles become less effective at reflecting light and produce more scattering. Eventually when the particles are very small, even less light is reflected to the eye and the material appears black. So depending upon the particle size, the color of silver can change from white to black.
Also, silver can react with chemicals present in air and tarnish. It is the reaction of silver with sulfides in the air to produce silver sulfide that turns silver black, but this is through a chemical reaction.
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1$\begingroup$ Fun fact: Gold nano particles appear purple-ish for the same reason. $\endgroup$– Martin - マーチン ♦Commented Sep 25, 2014 at 9:04
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