Question

Describe a chemical method for the preparation of sol of platinum in water. 

Answer 1

Method: A chemical reduction method is used to prepare colloidal platinum.

Procedure: An aqueous solution of platinum chloride (PtCl₄) is reduced using a suitable reducing agent like hydrogen gas (H₂) or formaldehyde (HCHO). This results in the formation of a colloidal sol of platinum.

\[\ce{PtCl4 + 2H2 -> Pt (Colloidal) + 4HCl}\]

The platinum thus formed remains in the colloidal state in water.

This is an example of a reduction method for preparing metal sols.