Sulphur is burnt in an excess of air to produce sulphur dioxide gas
\(\text {S + O}_2\) → \(\text {SO}_2\)
Sulphur dioxide gas mixed with an excess of air at a temperature of 450 °C and a pressure of 1 atm is passed over vanadium(v) oxide to produce sulphur trioxide gas
\(\text {2SO}_2 + \text {O}_2\) ⇔ \(\text {2SO}_3\)
Sulphur trioxide gas is dissolved in concentrated sulphuric acid to produce oleum
\(\text {2SO}_3 + \text {H}_2 \text{SO}_4\) → \(\text {H}_2 \text S_2 \text O_7\)
Oleum is diluted with water to produce concentrated sulphuric acid
\(\text {H}_2 \text S_2 \text O_7 + \text H_2 \text O\) → \(\text {2H}_2 \text{SO}_4\)
Assess yourself by staged practices
