Find the formula unit mass of potassium chloride (KCl).

Atomic mass — K = 39 u; Cl = 35.5 u. [Pg. No. 180]

Given:

• Atomic mass of K = 39 u

• Atomic mass of Cl = 35.5 u

Formula unit mass of KCl

= Atomic mass of K + Atomic mass of Cl

$$= 39 \text{ u} + 35.5 \text{ u} = 74.5 \text{ u}$$

Formula unit mass of KCl = 74.5 u