Question

Calculate the relative molecular masses of (Use K = 39, Cl = 35.5, O = 16, C = 12, H = 1, Na = 23, N = 14, S = 32)
(a) potassium chlorate
(b) sodium acetate
(c) chloroform
(d) ammonium sulphate

Answer 1

(a) Relative molecular mass of potassium chlorate [KClO₃] = $(1\times 39)+(1\times 35.5)+(3\times 16)=39+35.5+48=122.5$
(b) Relative molecular mass of sodium acetate [CH₃COONa] = $(2\times 12)+(3\times 1)+(2\times 16)+(1\times 23)=24+3+32+23=82$
(c) Relative molecular mass of chloroform [CHCl₃] = $(1\times 12)+(1\times 1)+(3\times 35.5)=12+1+106.5=119.5$
(d) Relative molecular mass of ammonium sulphate [(NH₄)₂SO₄] = $(2\times 14)+(8\times 1)+(1\times 32)+(4\times 16)=28+8+32+64=132$