Question

Calculate the mass of:
(a) 0.2 mole of the elemental oxygen atoms
(b) 0.5 mole of water molecules

Answer 1

$\text{(a) Mass of one mole of elemental oxygen atom = 16 gm}$
$\text{Then, mass of 0.2 mole of oxygen atoms}=0.2\times 16=3.2\text{gm}$
$\text{(b) Mass of one mole of}{H}_{2}O\text{molecule}=(2\times 1)+16=18\text{gm}$
$\text{Then, the mass of 0.5 mole of}{H}_{2}O\text{molecule =}0.5\times 18=9\text{gm}$