Question

Calculate the molar mass of the following substances.
(a) Ethyne, C2H2
(b) Sulphur molecule, S8
(c) Phosphorus molecule, P4 (Atomic mass of phosphorus = 31)
(d) Hydrochloric acid, HCl
(e) Nitric acid, HNO3​

Answer 1

Answer:

Molar mass is defined as the mass of substance for a given amount. The amount of molecules or atoms or compounds present in one mole of substance is given by this. Molar mass SI unit is g/mol.

The molar mass of the following substances are as follows:

(a) Ethyne, C2H2

Molar mass of ethyne

C2H2 = 2 x 12 + 2 x 1

Molar mass of ethyne = 26 g

(b) Sulphur molecule, S8

Molar mass of sulphur molecule,

S8 = 8 x 32 = 256 g

(c) Phosphorus molecule, P4 (atomic mass of phosphorus = 31)

Molar mass of phosphorus molecule,

P4 = 4 x 31 = 124 g

(d) Hydrochloric acid, HCl

Molar mass of hydrochloric acid,

HCl = 1 + 35.5 = 36.5 g

(e) Nitric acid, HNO3

Molar mass of nitric acid,

HNO3 = 1 + 14 + 3 x 16 = 63 g