The mass of the potassium hydroxide solution is 60 g, the mass fraction of alkali in the solution is 30%.

The mass of the potassium hydroxide solution is 60 g, the mass fraction of alkali in the solution is 30%. How much hydrogen sulphide will react if a medium salt is produced?

Given:
m solution (KOH) = 60 g
ω (KOH) = 20%

To find:
V (H2S) -?

1) Write the equation of a chemical reaction:
2KOH + H2S => K2S + 2H2O;
2) Calculate the mass of KOH:
m (KOH) = ω (KOH) * m solution (KOH) / 100% = 20% * 60/100% = 12 g;
3) Calculate the amount of substance KOH:
n (KOH) = m (KOH) / M (KOH) = 12/56 = 0.21 mol;
4) Determine the amount of substance H2S:
n (H2S) = n (KOH) / 2 = 0.21 / 2 = 0.11 mol;
5) Calculate the volume of H2S (under normal conditions):
V (H2S) = n (H2S) * Vm = 0.11 * 22.4 = 2.5 liters.

Answer: The volume of H2S is 2.5 liters.