Question

Calculate mass of phosphoric acid required to obtain $53.4$ gm pyrophosphoric acid.

Answer 1

$2H_{3}P{O}_4\to H_3{P}_2{O}_7+H_{2}O$

From the given equation,

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

Molar mass of phosphoric acid $=98g$

mass of 2 moles of phosphoric acid $=2\times 98$ $=196g$

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

Given,

mass of pyrophosphoric acid produced$=53.4g$

number of moles in 53.4 g of phosphoric acid = $53.4÷177.9=0.3$

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