SO2 with a volume of 30 liters passed through a 20% NaOH solution with a mass of 120 g Find: m (Formed salt).

When sulfur dioxide is passed through an alkali solution, a salt is formed – sodium sulfite.
SO2 + 2NaOH = Na2SO3 + H2O.
Determine the mass of alkali in the solution.
m (NaOH) = 120 g • 20% / 100% = 24 g.
Let’s determine the number of moles of substances.
n (NaOH) = m / Mr = 24 g / 40 g / mol = 0.6 mol.
n (SO2) = V / Vm = 30 L / 22.4 mol / L = 1.34 mol.
Sulfur oxide is in excess, so the calculation is based on a shortage.
If, according to the reaction equation, 1 mol of salt is formed from 2 mol of sodium hydroxide, then from 0.6 mol – x mol of sodium salt.
n (Na2SO3) = 0.6 * 1/2 = 0.3 mol.
The mass of the salt formed.
m (Na2SO3) = n • Mr = 0.3 mol • 126 g / mol = 37.8 g.