Question

Calculate the molecular masses of $H_2,O_2,C{O}_2,N{H}_3,C{H}_{3}OH.$ [5 MARKS]

Answer 1

Each point: 1 Mark

1. Molecular mass of $H_2$ = 2 x Atomic mass of H

= 2 x 1

= 2 u

2. Molecular mass of $O_2$= 2 x Atomic mass of O

= 2 x 16

= 32 u

3. Molecular mass of $C{O}_2$= Atomic mass of C + 2 x Atomic mass of O

= 12 + 2 x 16

= 44 u

4. Molecular mass of $N{H}_3$ = Atomic mass of N + 3 x Atomic mass of H

= 14 + 3 x 1

= 17 u

5. Molecular mass of $C{H}_{3}OH$= Atomic mass of C + Atomic mass of O + 4 x Atomic mass of H

= 12+ 16 + 4 x 1

= 32 u