Question

Mercury can be obtained by reacting mercury(I) sulfide with calcium oxide. How many grams of calcium oxide are needed to produce 55.0 g of Hg? Note: 4 Hg2S + 4 CaO -> 8 Hg + 3 CaS + 1 CaSO4

Answer 1

First, 55 g of Hg is 3.65 moles because one mole of Hg has a molar mass of 200.59

Then, the mole ratio of Hg to CaO is 8:4 or 2:1. SO we divide 3.65 by 2 to get 1.82 moles of CaO

This is the same as 102.06 grams because one mole of CaO has a molar mass of 56.0774

Hope this helps!