Fe3+ is yellow, SCN- is colourless, and the [FeSCN]2+ is a very deep blood red. How is it red?!

Question

I don't get how it's red if one's yellow and the other is colorless. How does it turn red?

Answer 1

A color change indicates a reaction has taken place (new chemical elements or compounds have been formed). When the 2+ ion is formed a chemical reaction has taken place, and the formed ionic solution is red. The fact that the original reactants are different colours is irrelevant.