Question

Question 1 Calculate the molecular masses of H2, O2, Cl2, CO2, CH4, C2H6, C2H4, NH3, CH3OH.

Class 9 - Science - Atoms and Molecules Page 40

Answer 1

hey,

molecular mass of H₂= 2× atomic mass of H 
                                  = 2×1 = 2 u.

molecular mass of O₂= 2× atomic mass of O
                                   = 2 × 16u = 32 u.

molecular mass of Cl₂= 2 × atomic mass of Cl
                                   = 2 × 35.5 u= 71 u.

molecular mass of CO₂=  atomic mass of C + 2 × atomic mass of O
                                     = 12 + 2×16
                                     = 12+ 32= 44 u.

molecular mass of CH₄= atomic mass of C + 4 × atomic mass of H
                                     = 12+ 4×1= 16 u.

molecular mass of C₂H₆= 2 × 12 + 6 × 1
                                      = 30 u.

molecular mass of C₂H₄= 2 × 12 + 4 × 1
                                       = 28 u.

molecular mass of NH₃= 14+ 3×1
                                     = 17 u.

molecular mass of CH₃OH= 12 + 3× 1+ 16 × 1
                                           = 32 u.

hope it helps..

Answer 2

HI there !

Molar masses :-
Hydrogen = H = 1 u
Oxygen = O = 16 u
Chlorine = Cl = 35.5 u
Carbon = C = 12 u
Nitrogen = N = 14 u

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1) Molecular mass of H₂ = 2 x 1 = 2 u

2) Molecular mass of O₂ = 2 x 16 = 32 u

3) Molecular mass of Cl₂ = 2 x 35.5 = 71 u

4) Molecular mass of CO₂ = 1 x 12 + 2 x 16 = 44 u

5)Molecular mass of CH₄ = 1 x 12 + 4 x 1 = 16 u

6)Molecular mass of C₂H₆ = 2 x 12 + 6 x 1 = 30 u

7)Molecular mass of C₂H₄ = 2 x 12 + 4 x 1 = 28 u

9)Molecular mass of NH₃ = 1 x 14 + 3 x 1 = 17 u

10) Molecular mass of CH₃OH = 1 x 12 + 3 x 1 + 1 x 16 + 1 x 1 = 32 u