To 9.8 g of orthophosphoric acid was added 12.7 g of sodium hydroxide. Let’s determine the mass of the formed salt.

Reaction equation: H3PO4 + 3NaOH = Na3PO4 + 3H2O.
1) Find the amount of phosphoric acid substance. To do this, we divide its mass by molar mass: 9.8 / 98 = 0.1 mol.
2) Find the amount of sodium hydroxide substance. Similar to the first point: 12.7 / 40 = 0.32 mol.
Lack of phosphoric acid. The calculation is carried out on it.
3) According to the reaction equation, 1 mol of sodium phosphate accounts for 1 mol of orthophosphoric acid. This means that the amount of sodium phosphate substance is 0.1 mol.
4) Mass of sodium phosphate: 0.1 * 164 = 16.4 g – answer.