Calculate the molecular masses of H_2, O₂, C_l2, C0_2, CH₄, C₂H_2, NH₃, CH₃OH.

The total sum of the masses of the atoms or elements present in the molecule is termed molecular mass.

i) Molecular mass of H₂= 2 x Atomic mass of H

= 2 x 1

ii) Molecular mass of O₂= 2 x Atomic mass of O

= 2 x 16

iii) Molecular mass of Cl₂= 2 x Atomic mass of Cl

= 2 x 35.5

iv) Molecular mass of CO₂= Atomic mass of C + 2 x Atomic mass of O

= 12 + 2 x 16

v) Molecular mass of CH₄= Atomic mass of C + 4 x Atomic mass of H

= 12 + 4 x 1

vi) Molecular mass of C₂H₆= 2 x Atomic mass of C + 6 x Atomic mass of H

= 2 x 12 + 6 x 1

vii) Molecular mass of C₂H₄= 2 x Atomic mass of C + 4 x Atomic mass of H

= 2 x 12 + 4 x 1

viii) Molecular mass of NH₃= Atomic mass of N + 3 x Atomic mass of H

= 14 + 3 x 1

ix) Molecular mass of CH₃OH= Atomic mass of C + 4 x Atomic mass of H + 1 x Atomic mass of

= 12 + 4 x 1 + 16