To a solution containing 7.1 g of sodium sulfate was added a solution of barium chloride. Calculate the mass of the precipitate formed.

Let’s find the amount of sodium sulfate Na2SO4 by the formula:

n = m: M.

M (Na2SO4) = 142 g / mol.

n = 7.1 g: 142 g / mol = 0.05 mol.

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

Na2SO4 + BaCl2 = BaSO4 ↓ + 2NaCl.

According to the reaction equation, there is 1 mol of BaSO4 for 1 mol of Na2SO4.

The substances are in quantitative ratios of 1: 1.

The amount of substance will be equal.

n (BaSO4) = n (Na2SO4) = 0.05 mol.

Let’s find the mass of ВаSO4.

M (BaSO4) = 233 g / mol.

m = n × M.

m = 233 g / mol × 0.05 mol = 11.65 g.

Answer: 11.65 g.