Determine the mass fraction of HCl in a solution of hydrochloric acid weighing 200

Determine the mass fraction of HCl in a solution of hydrochloric acid weighing 200 grams if metallic aluminum weighing 2.7 grams is dissolved in it.

The reaction of interaction of aluminum with hydrochloric acid is described by the following chemical equation:

Al + 3HCl = AlCl3 + 3/2 H2;

When 1 molecule of metal is dissolved, 1 molecule of aluminum chloride is formed. This requires 3 molecules of hydrochloric acid and 1.5 hydrogen molecules are released, containing 6 atoms of this element.

Let’s calculate the chemical amount of a substance in 2.7 grams of metal.

M Al = 27 grams / mol;

N Al = 2.7 / 27 = 0.1 mol;

To dissolve this mass of metal, it is necessary to take 0.1 x 3 = 0.3 mol of acid.

Let’s calculate its weight.

M HCl = 1 + 35.5 = 36.5 grams / mol;

m HCl = 0.3 x 36.5 = 10.95 grams;

the mass fraction of acid in a solution weighing 200 grams will be 10.95 / 200 = 0.05475 = 5.475%;