Sulphur is converted to sulphuric acid in three stages: $S SO X_{2} SO X_{3} H X_{2} SO X_{4}$ . Starting from 16 g of sulphur ( $S = 32$ ) and an overall yield of 80%, find the mass of $H X_{2} SO X_{4}$ ( $M = 98$ ) obtained, in grams, to two decimal places.

Numerical answer type, answer in g, tolerance 0.05.

Answer: 39.2 g

Each S atom ends up in one

H X_{2} SO X_{4}

. Moles of S = 16/32 = 0.5, so theoretical

H X_{2} SO X_{4}

= 0.5 x 98 = 49 g. At 80% overall yield mass = 49 x 0.80 = 39.20 g.