Calculate the mass of potassium hydroxide required for the reaction with a solution containing 0.4 mol of sulfuric acid.

Given:
KOH reacts with H2SO4 solution
v (H2SO4) = 0.4 mol – amount of substance (nu)
Find: m (KOH) -?
Decision:
2KOH + H2SO4 = K2SO4 + H2O
1) Find the amount of substance v for KOH
Since KOH and H2SO4 are initial substances and are in the same chemical reaction system, the ratio can be drawn:
The ratio will be 2: 1, which means
v (KOH) / 2 mol = 0.4 mol / 1 mol
v (KOH) = 0.8 mol.
2) Find the mass for KOH:
M (KOH) = 1 + 16 + 49 = 56 g / mol.
m (KOH) = 56 g / mol * 0.8 mol = 44.8 g.
Answer: m (KOH) = 44.8 g.