Question

Calculate the molecular masses of the following compounds :
(a) Methane, CH₄
(b) Ethane, C₂H₆
(c) Ethene, C₂H₄
(d) Ethyne, C₂H₂

(Atomic masses : C = 12 u ; H = 1 u)

Answer 1

(a) Given:
Atomic mass of C = 12 u
Atomic mass of H = 1 u
Therefore, molecular mass of CH₄ (methane) can be calculated as follows:
(1 × 12) + (4 × 1) = 16
Hence, molecular mass of methane is 16 u.

(b) Given:
Atomic mass of C = 12 u
Atomic mass of H = 1 u
Therefore, molecular mass of C₂H₆ (ethane) can be calculated as follows:
(2 × 12) + (6 × 1) = 30
Hence, molecular mass of ethane is 30 u.

(c) Given:
Atomic mass of C = 12 u
Atomic mass of H = 1 u
Therefore, molecular mass of C₂H₄ (ethylene) can be calculated as follows:
(2 × 12) + (4 × 1) = 28
Hence, molecular mass of ethylene is 28 u.

(d) Given:
Atomic mass of C = 12 u
Atomic mass of H = 1 u
Therefore, molecular mass of C₂H₂ (acetylene) can be calculated as follows:
(2 × 12) + (2 × 1) = 26
Hence, molecular mass of acetylene is 26 u.