Question

Question 6 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

Class 9 - Science - Atoms and Molecules Page 44

Answer 1

Heya !


Here is your answer ==============================================================================

>> The molar masses of all these substances will be equal to the respective molecular masses expressed in g / mol . Now :

(a) Molar mass of ethyne, C2H2 = Mass of C × 2 + Mass of H × 2

= 12 × 2 + 1 × 2

= 24 + 2

= 26 g / mol

(b) Molar mass of sulphur molecule, S8 = Mass of S × 8

= 32 × 8

= 256 g/ mol

(c) Molar mass of phosphorus molecule , P4 = Mass of P × 4

= 31 × 4

= 124 g / mol

(d) Molar mass of hydrochloric acid, HCl = Mass of H + Mass of Cl

= 1 + 35.5

= 36. 5 g/ mol

(e) Molar mass of nitric acid , HNO3 = Mass of H + Mass of N + Mass of O × 3

= 1 + 14 + 16 × 3

= 15 + 48

= 63 g / mol


Hope it helps !!! : )

Answer 2

The answer is in the above attachment.