How many grams of phosphoric acid will be obtained at 70% yield if 7.1 grams of phosphorus oxide are dissolved in water?

Let’s calculate the chemical amount of a substance in phosphorus oxide weighing 7.1 grams.
M P2O5 = 31 x 2 + 16 x 5 = 142 grams / mol;
N P2O5 = 7.1 / 142 = 0.05 mol;
The phosphorus oxide molecule contains 2 phosphorus atoms, and the phosphoric acid molecule contains 1 phosphorus atom. Therefore, from 0.05 mol of phosphorus oxide, 0.05 x 2 = 0.1 mol of acid can be obtained.
Let’s calculate its weight.
To do this, multiply the amount of the substance by its molar weight.
М Н3РО4 = 3 + 31 + 16 x 4 = 98 grams / mol;
m Н3РО4 = 0.1 x 98 = 9.8 grams.
Taking into account 70% of the yield, the mass of phosphoric acid will be:
m Н3РО4 = 9.8 x 0.7 = 6.86 grams.