# How many liters of hydrogen are formed when sodium interacts with 20 g of 20% hydrochloric acid solution?

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) = (20 g × 20%): 100% = 4 g.

Let’s find the amount of hydrochloric acid substance by the formula:

n = m: M.

M (HCl) = 36 g / mol.

n = 4 g: 36 g / mol = 0.11 mol.

Let’s compose the reaction equation, find the quantitative ratios of substances.

2Na + 2HCl = 2NaCl + H2 ↑.

According to the reaction equation, 2 mol of hydrochloric acid accounts for 1 mol of hydrogen. Substances are in quantitative ratios of 2: 1.

The amount of hydrogen substance will be 2 times less than the amount of hydrochloric acid substance.

n (H2) = 2n (HCl) = 0.11: 2 = 0.055 mol.

Let’s find the volume of hydrogen.

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 = 0.055 mol × 22.4 L / mol = 1.23 L. 