Question

calculate the mass of phosphoric acid required to obtain 53.4g pyrophorshric acid

Answer 1

Molecular mass of pyrophosphoric acid = 177.98 g/mol

mass of pyrophosphoric acid produced = 53.4 g

molar mass of phosphoric acid =  98 g/mol 

number of moles in 53.4 g of phosphoric acid = 53.4/ 177.98 = 0.3

 

From the above eqn.

1 mol of pyrophosphoric acid is produced by 2 mol of phosphoric acid

mass of 2 moles of phosphoric acid = 2 x 98 = 196 g

mass of phosphoric acid required for formation of 1 mol of pyrophosphoric acid = 196 g 

mass of phosphoric acid required for formation of 0.3 mol of pyrophosphoric acid = 0.3 x 196 = 58.8 g