Give the chemical formulae for the following compounds and compute the ratio by mass of the combining elements in each one of them. (You may use appendix-III).
(a) Ammonia
(b) Carbon monoxide
(c) Hydrogen chloride
(d) Aluminium fluoride
(e) Magnesium sulphide
(Aluminium fluoride a) Ammonia = NH3
The atomic mass of N = 14
The atomic mass of H = 1
Thus, Ratio by mass = N : H × 3
= 14 : 1 × 3
= 14:3
(b) Carbon monoxide = CO
The atomic mass of C = 12
The atomic mass of O = 16
Thus, Ratio by mass = C:O
= 12:16
= 3:6
(c) Hydrogen chloride = HCl
The atomic mass of H = 1
The atomic mass of Cl = 35.5
Thus, Ratio by mass = H : Cl
= 1:35.5
(d) Aluminium fluoride = AlF3
The atomic mass of Al = 27
The atomic mass of F = 19
Thus, Ratio by mass = Al : F × 3
= 27 : 19 × 3
= 27 : 57
= 9 : 19
(e) Magnesium sulphide = MgS
The atomic mass of Mg = 24
The atomic mass of S = 32
Thus, Ratio by mass = Mg : S
= 24 : 32
= 3 : 4