Question

Find the formula mass of : 

i. KCl 

ii. AgCl

Atomic mass of K = 39 u, Ag =108 u and Cl = 35.5 u.

Answer 1

i. Formula mass of KCl

= Average atomic mass of K + Average atomic mass of Cl 

= 39 u + 35.5 u 

= 74.5 u

ii. Formula mass of AgCl 

= Average atomic mass of Ag + Average atomic mass of Cl 

= 108 + 35.5 

= 143.5 u

∴ i. Formula mass of KCl = 74.5 u

ii. Formula mass of AgCl = 143.5 u