How many grams of NaOH is needed to neutralize 47.4 grams of H3PO4.

Let’s find the amount of substance H3PO4 by the formula:

n = m: M.

M (H3PO4) = 98 g / mol.

n = 47.7 g: 98 g / mol = 0.48 mol.

Let’s compose the reaction equation, find the quantitative ratios of substances.

3 NaOH + H3PO4 = Na3PO4 + 3H2O

According to the reaction equation, there is 3 mol of NaOH for 1 mol of H3PO4.

The substances are in quantitative ratios of 1: 3. The amount of NaOH substance is 3 times more than the amount of H3PO4 substance.

n (NaOH) = 3n (H3PO4) = 0.48 × 3 = 1.44 mol.

Let’s find the mass of NaOH by the formula:

m = n × M,

M (NaOH) = 40 g / mol.

m = 1.44 mol × 40 g / mol = 57.6 g.

Answer: 57.6 g.