Question

Question #6d52d

Answer 1

Colorless salts:
The transparent salts are mostly mono crystalline (they are a single crystal), I.e. they have an unbroken and continuous crystal lattice with no grain boundaries.

Explanation:

To understand this concept, you need to learn about two things.

1) Mono crystalline or simply Single crystals, which have an unbroken and continuous crystal lattice,

I.e they have only one continuous crystal with no grain boundaries (grain boundaries are like a boundary between two crystals,
since there is only crystal so no grain boundaries).

Now the reason I am telling you all this is that, light reflects from the grain boundaries, since there are no boundaries, so no light reflects and hence no color.

For example: Sodium chloride, Magnesium Sulfate and heptahydrate are colorless salts.

On the flip side:

2) Poly crystalline salts

Have so many grain boundaries, I.e a lot of crystals joined together at those boundaries,

So lights reflects from those grain boundaries and hence we got Colorful salts..

For example: Nickel chloride (green), sodium chromate (yellow), cobalt nitrate(red).

Mono crystalline Salts = Colorless Salts
Poly crystalline Salts = Colorful Salts

Hope this helps!! ^_^