Question

Reaction of copper metal with silver ion. When copper metal is placed in a solution of silver nitrate, a redox reaction forms silver metal and a blue solution of copper(II) nitrate. Why does this solution turn blue?

Answer 1

Explanation:

The ionic reaction of the copper and the silver ions is shown below:

$Cu+2Ag^+\rightarrow Cu^{2+}+2Ag$

Copper gives up 2 electrons and transfers to 2 silver ions which gives solid silver (reduction) and copper (II) ions.

The blue color of the solution is due to the formation of copper (II) ions. The electrons in the copper ion shows d-d transition which absorbs light in the visible region and shows blue color.