Calculate the mass of the salt obtained by the interaction of 245 g of 20% sulfuric acid solution with sodium hydroxide.

Given:

m (H2SO4) = 245 g

w% (H2SO4) = 20%

Find:

m (salt) -?

Solution:

2NaOH + H2SO4 = Na2SO4 + 2H2O, – we solve the problem based on the composed reaction equation:

1) Find the mass of sulfuric acid in the reacted solution:

m (H2SO4) = 245 g * 0.2 = 49 g

2) Find the amount of acid:

n (H2SO4) = m: M = 49 g: 98 g / mol = 0.5 mol

3) We compose a logical expression:

If 1 mol of H2SO4 gives 1 mol of Na2SO4,

then 0.5 mol H2SO4 will give x mol Na2SO4,

then x = 0.5 mol.

4) Find the mass of sodium sulfate formed during the reaction:

m (Na2SO4) = n * M = 0.5 mol * 142 g / mol = 71 g.

Answer: m (Na2SO4) = 71 g.