Question

35g of HF was prepared by reacting 112g of CaF2 with an excess of H2SO4 calculate the percentage yield

Answer 1

Answer: 61%

The reaction equation should be

CaF2 + H2SO4 → 2HF + CaSO4

For every 1 molecule CaF2 used, there will be 2 molecules of HF formed. The molecular mass of CaF2 is 78/mol while the molecular mass of HF is 20g/mol. If the yield is 100%, the amount of HF formed by 112g CaF2 would be: 112g/(78g/mol) * 2 * (20g/mol)=57.43g

The percentage yield of the reaction would be: 35g/57.43g= 60.94%