## Calculate the molar mass of the following substances.

(a) Ethyne, C 2 H 2

(b) Sulphur molecule, S 8

(c) Phosphorus molecule, P 4 (Atomic mass of phosphorus = 31)

(d) Hydrochloric acid, HCl

(e) Nitric acid, HNO 3

Molar mass of C = 12g

Molar mass of H = 1g

Molar mass of S = 32g

Molar mass of P = 31g

Molar mass of Cl = 35.5g

Molar mass of N = 14g

Molar mass of O = 16g

#### (a) Ethyne, C 2 H 2

Molar mass of C 2 H 2 = 2 x Molar mass of C + 2 x Molar mass of H

= 2x 12g + 2 x 1g

= 24g + 2g

= 26g

#### (b) Sulphur molecule, S 8

Molar mass of S 8 = 8 x Molar mass of S

= 8x 32g

= 256g

#### (c) Phosphorus molecule, P 4

Molar mass of P 4 = 4 x Molar mass of P

= 4 x 31g

= 124g

#### (d) Hydrochloric acid, HCl

Molar mass of HCl = 1 x Molar mass of H + 1 x Molar mass of Cl

= 1x 1g + 1 x 35.5g

= 1g + 35.5g

= 36.5g

#### (e) Nitric acid, HNO 3

Molar mass of HNO 3 = 1 x Molar mass of H + 1 x Molar mass of N + 3 x Molar mass of O

=1x 1g + 1 x 14g + 3 x 16g

= 1g + 14g + 48g

= 63g

1. Class 9
2. Chapter 3 Class 9 - Atoms And Molecules (Term 2)
3. NCERT Questions

NCERT Questions

Class 9
Chapter 3 Class 9 - Atoms And Molecules (Term 2) 