A solution of hydrochloric acid weighing 29.2 g and a mass fraction of 5% was added to the excess of magnesium sulfite. Calculate the amount of gas released
Find the mass of hydrochloric acid in the solution.
The mass fraction of a substance is calculated by the formula:
W = m (substance): m (solution) × 100%,
m (substance) = (m (solution) × W): 100%,
m (substance) = (29.2 g × 5%): 100% = 1.46 g.
Let’s find the amount of hydrochloric acid substance by the formula:
n = m: M.
М (HCl) = 36.5 g / mol.
n = 1.46 g: 36.5 g / mol = 0.04 mol.
Let’s compose the reaction equation, find the quantitative ratios of substances.
MgSO3 + 2HCl = MgСl2 + SO2 ↑ + Н2О.
According to the reaction equation, there is 1 mol of gas for 2 mol of hydrochloric acid. Substances are in quantitative ratios of 2: 1.
The amount of sulfur dioxide substance will be 2 times less than the amount of hydrochloric acid substance.
n (SO2) = ½ n (HCl) = 0.04: 2 = 0.02 mol.
Let’s find the volume of the gas.
V = Vn n, where Vn is the molar volume of gas, equal to 22.4 l / mol, and n is the amount of substance.
V = 0.02 mol × 22.4 L / mol = 0.448 L.
Answer: 0.448 l.