Question

Cinnabar (HgS) is a prominent ore of mercury. How many grams of mercury are present in 225 g of pure HgS? Molar mass of Hg and S are 200.6 g mol^–1 and 32 g mol–1 respectively. 

Answer 1

Molar mass of HgS = 200.6 + 32 = 232.6 g mol^–1 

Mass of Hg in 232.6 g of HgS = 200.6 g 

Mass of Hg in 225 g of HgS 232.6 / 200.6 = × 225 = 194.04g