Question

Write the name of the following compound and deduce its molecular mass.

K₂CO₃

Answer 1

K₂CO₃ - Potassium carbonate

Molecule	Constituent elements	Atomic mass u	Number of atoms in the molecule	Atomic mass × number of atoms	Mass of the Constituents u
K2CO3	K	39	2	39 × 2	78
	C	12	1	12 × 1	12
	O	16	3	16 × 3	48

The Molecular mass of K₂CO₃ = Sum of Constituent atomic masses

(Molecular mass of K₂CO₃) = (Atomic mass of K) × 2 + (Atomic mass of C) × 1 + (Atomic mass of O) × 3

= (39 × 2) + (12 × 1) + (16 × 3)

= 78 + 12 + 48

= 138 u