Question

Calculate the mass of 18.066×1023 number of NH3 molecules. (Given atomic mass of nitrogen= 14 u and hydrogen=1 u)

Answer 1

Explanation:

(a) 1 mole of nitrogen atoms=1×mass of N=1×14=14 g

(b) 4 moles of aluminium atoms=4×27=108 g

(c) 10 moles of sodium sulphite(Na

2

SO

3

)=10×Mass of Na

2

SO

3

.

Mass of Na

2

SO

3

=2×Mass of Na atom+1×Mass of S atom+3×Mass of O atom

=2×23+1×32+3×16=46+32+48=126 g/mol

∴10 moles of Na

2

SO

3

=10×126=1260 g