Calculate the number of moles in each of the following :
(i) 392g of sulphuric acid
(ii) 44.8 g litres of sulphur dioxide at N.T.P
(iii) `6.022 xx 10^(22)` molecules of oxygen
(iv) 8 g of calcium.

Explanation

(i) 392 g of sulphuric acid
Molar mass of `H_(2)SO_(4) = 2 xx 1+32 +4 xx 16 = 98 g`
98 g of sulphuric acid = 1 mol
392 g of sulphuric acid = 1 mol `xx (392g)/((98g))=4` mol
(ii) 44.8 litres of sulphuric dioxide at N.T.P
22.4 litres of sulphur dioxide at N.T.P = 1 mol
44.8 litres of sulphur dioxide N.T.P
22.4 litres of sulphur dioxide at N.T.P = 1 mol
44.8 litres of sulphur dioxide at N.T.P = `(1mol)/((2.4 L))xx(44.8L)=2.0` mol
(iii) `6.022 xx 10^(22)` molecules of oxygen
`6.022 xx 10^(23)` molecules of oxygen = 1 mol
`6.022 xx 10^(22)` molecules of oxygen `= 1 mol xx (6.022xx10^(22))/(6.022xx10^(23)) = 0.1` mol
(iv) 8g of calcium
Gram atomic mass of Ca = 40 g
40 g of calcium = 1 mol
8.0 g of calcium = 1 mole `xx ((8.0 g))/((40 g)) = 0.2 `mol.