In 400 mg of a 25% potassium hydroxide solution, 45% carbon dioxide was dissolved. Calculate the mass of the salt formed.

The problem for the excess and lack of reagents.

Let’s find the amount of the substance KOH and CO2:

m (KOH) = 0.4 x 0.25 = 0.1 g;

n (KOH) = 0.1 / 56 = 0.0018 mol;

Let’s find the mass of carbon dioxide. It is known that after dissolution, its mass fraction (excluding the reaction) was 45%. Let m be the mass of dissolved CO2, then:

m (CO2) / (m (CO2) + 0.4) = 0.45;

m (CO2) = 0.28 g;

n (CO2) = 0.28 / 44 = 0.0063 mol;

Carbon dioxide in excess, the reaction of formation of potassium bicarbonate will proceed:

KOH + CO2 = KHCO3

n (salt) = n (KOH) = 0.0018 mol;

m (salt) = 0.0018 × 100 = 0.18 g

Answer: m (salt) = 0.18 g.