Find the mass of salt if 15 g of sodium hydroxide has reacted with sulfuric acid.

Let’s find the amount of substance NaOH.

n = m: M.

M (NaOH) = 40g / mol.

n = 15 g: 40 g / mol = 0.375 mol.

Let’s find the quantitative ratios of substances.

2NаОH + H2SO4 → Na2SO4 + 2Н2О.

For 2 mol of NaOH, there is 1 mol of Na2SO4.

Substances are in quantitative ratios of 2: 1.

The amount of Na2SO4 substance will be 2 times less than NaOH ..

n (Na2SO4) = ½ n (NaOH) = 0.375: 2 = 0.188 mol.

Let’s find the mass of Na2SO4.

m = n × M.

M (Na2SO4) = 142 g / mol.

m = 142 g / mol × 0.188 mol = 26.7 g.

Answer: 26.7 g.



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