Calculate the mass of potassium hydroxide required to completely neutralize 150 g of a 15% sulfuric acid solution.

Given:

m (H2SO4) = 150 g

w% (H2SO4) = 15%

Find:

m (KOH) -?

Solution:

2KOH + H2SO4 = K2SO4 + 2H2O, – we solve the problem based on the composed reaction equation:

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

m (H2SO4) = 150 g * 0.15 = 22.5 g

2) Find the amount of sulfuric acid:

n (H2SO4) = m: M = 22.5 g: 98 g / mol = 0.23 mol

3) We compose a logical expression:

If 1 mol of H2SO4 requires 2 mol of KOH,

then 0.23 mol H2SO4 will require x mol KOH,

then x = 0.46 mol.

4) Find the mass of alkali required for the reaction:

m (KOH) = n * M = 0.46 mol * 56 g / mol = 25.76 g.

Answer: m (KOH) = 25.76 g.