Question

When 0.5 gram of sulphur is burnt to form SO₂, 4.6 kJ of heat liberated. Calculate enthalpy of formation of SO₂(g). (Atomic mass : S = 32, O = 16)

Options

• - 294.4 kJ mol^-1

• - 172.4 kJ mol^-1

• - 81.2 kJ mol^-1

• - 258.6 kJ mol^-1

Answer 1

- 294.4 kJ mol^-1 

Explanation:

\[\ce{S + O2 -> SO2; \Delta H_f = - 4.6 kJ}\]

0.5 g of sulphur on burning produce 1 g of SO₂.

∴ 32 g of sulphur on burning will produce 64 g of SO₂.

∴  `Delta "H"_"f" = (- 4.6 " kJ") xx 64 = - 294.4` kJ mol^-1