6 g of a mixture consisting of powders of aluminum and copper was treated with an excess of hydrochloric

6 g of a mixture consisting of powders of aluminum and copper was treated with an excess of hydrochloric acid, while 3.7 liters of hydrogen were released. Calculate the mass fraction (%) of each metal in the mixture.

Copper does not react with hydrochloric acid under normal conditions.

Aluminum reacts with hydrochloric acid. This forms an aluminum chloride salt and releases hydrogen gas. The reaction is described by the following chemical equation.

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

Let’s calculate the chemical amount of synthesized hydrogen gas. To do this, we find the ratio of its volume to the volume of 1 mole of gas (filling a space with a volume of 22.4 liters).

N H2 = 3.7 / 22.4 = 0.165 mol;

To synthesize such an amount of gaseous hydrogen, it is necessary to take 0.165 x 2/3 = 0.11 mol of metallic aluminum.

Let’s calculate its mass.

For this purpose, we multiply the amount of the substance by the molar weight of this chemical element.

M Al = 27 grams / mol; m Al = 0.11 x 27 = 2.97 grams;

Determine the mass fraction of metallic aluminum:

K = 2.97 / 6 = 0.495 = 49.5%; The mass fraction of copper will be: 100 – 49.5 = 50.5%;