Calculate the mass of the precipitate that forms when barium hydroxide reacts with 120 g of a 25%

Calculate the mass of the precipitate that forms when barium hydroxide reacts with 120 g of a 25% sulfuric acid solution.

Given:

m (H2SO4) = 120 g

w% (H2SO4) = 25%

To find:

m (BaSO4) -?

Decision:

Ba (OH) 2 + H2SO4 = BaSO4 + 2H2O, – we solve the problem based on the composed reaction equation:

1) Find the mass of sulfuric acid that has reacted:

m (H2SO4) = 120 g * 0.25 = 30 g

2) Find the amount of sulfuric acid:

n (H2SO4) = m: M = 30 g: 98 g / mol = 0.3 mol

3) We compose a logical expression:

If 1 mol of H2SO4 gives 1 mol of BaSO4,

then 0.3 mol of H2SO4 will give x mol of BaSO4,

then x = 0.3 mol.

4) Find the mass of barium sulfate precipitated during the reaction:

m (BaSO4) = n * M = 0.3 mol * 233 g / mol = 69.9 g ~ 70 g.

Answer: m (BaSO4) = 69.9g ~ 70g.