Hitung massa molekul H2, O2, Cl2, CO2, CH4, C2H6, C2H4, NH3, CH3OH.

Penyelesaian:

Jumlah total massa atom atau unsur yang ada dalam molekul disebut massa molekul.

1. i) Massa molekul H ₂ = 2 x Massa atom H

= 2×1

Massa molekul H ₂ = 2 u

1. ii) massa molekul O ₂ = 2 x Atom massa O

= 2 x 16

Massa molekul O ₂ = 32 u

iii) Massa molekul Cl ₂ = 2 x Massa atom Cl

= 2 x 35,5

Massa molekul Cl ₂ = 71 u

1. iv) Massa molekul CO ₂ = Massa atom C + 2 x Massa atom O

= 12 + 2 x 16

Massa molekul CO ₂ = 44 u

1. v) Massa molekul CH ₄ = Massa atom C + 4 x Massa atom H

= 12 + 4 x 1

Massa molekul CH ₄ = 16 u

1. vi) Massa molekul C ₂ H ₆ = 2 x Massa atom C + 6 x Massa atom H

= 2 x 12 + 6 x 1

Massa molekul C ₂ H ₆ = 30 u

vii) Massa molekul C ₂ H ₄ = 2 x Massa atom C + 4 x Massa atom H

= 2 x 12 + 4 x 1

Massa molekul C ₂ H ₄ = 28 u

viii) Massa molekul NH ₃ = Massa atom N + 3 x Massa atom H

= 14 + 3 x 1

Massa molekul NH ₃ = 17 u

1. ix) Massa molekul CH ₃ OH = Massa atom C + 4 x Massa atom H + 1 x Massa atom

= 12 + 4 x 1 + 16

Massa molekul CH ₃ OH = 32 u

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