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28/12/2020 12:43 pm
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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
1 Answer
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28/12/2020 12:54 pm
(a) Molar mass of C2H2
= 2 x atomic mass of C + 2 x atomic mass of H
= (2 x 12 + 2 x 1)u = (24 + 2)u = 26u
(b) Molar mass of S = 8 × atomic mass of s = (8 × 32)u = 256 u
(c) Molar mass of P4 = 4 x atomic mass of H + atomic mass of Cl
= (1 + 31)u = 124 u
(d) Molar mass of HCl = atomic mass of H + atomic mass of Cl
= (1 + 35.5)u = 36.5
(e) Molar mass of HNO3 = atomic mass of H + atomic mass of N + 3 x atomic mass of O
= (1 + 14 + 3 x 16)u = (1 + 14 + 48)u
= 63 u