What volume of gas will be released when 12 g of magnesium react with 400 g of a 20% sulfuric acid solution.
Find the mass of sulfuric acid in the solution.
W = m (substance): m (solution) × 100%,
hence m (substance) = (m (solution) × w): 100%.
m (substance) = (400 g × 20%): 100% = 80 g.
Let’s find the amount of the substance H2SO4.
n = m: M.
M (H2SO4) = 98 g / mol.
n = 80 g: 98 g / mol = 0.816 mol.
Let’s find the amount of Mg substance.
M (Mg) = 24g / mol.
n = 12 g: 24 g / mol = 0.5 mol.
H2SO4 is given in excess. We solve the problem by Mg.
Let’s find the quantitative ratios of substances.
Mg + H2SO4 = MgSO4 + H2 ↑.
For 1 mole of Mg, there is 1 mole of H2.
Substances are in quantitative ratios 1: 1.
The amount of substance will be equal.
n (H2) = n (Mg) = 0.5 mol.
Let’s find the volume of CO2.
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 = 0.5 mol × 22.4 L / mol = 11.2 L.
Answer: 11.2 liters.