Question

Calculate the mass of the following :- (i) 0.5 mole of N₂ gas.
(ii) 0.2 mole of O atoms
(iii) 4 moles of aluminium atoms

Answer 1

1) Number of moles (n) = 0.5 moles
Molar mass of N₂ = 28 g mol^​-1
$n=\frac{Givenmass}{Molarmass}$

$Givenmass=0.5\times 28$
Hence , mass of a substance = 14 g

2) n = 0.2 mole
Molar mass of oxygen atom = 16 g mol^-1
Mass of substance = $16\times 0.2$ = 3.2 g

3) n = 4 moles of aluminium atoms
Molar mass of aluminium = 27 g mol^-1
Given mass = $27\times 4$ = 108 g