A mixture of aluminum and copper powders weighing 20 grams was treated with a sulfuric acid solution, resulting in the release

A mixture of aluminum and copper powders weighing 20 grams was treated with a sulfuric acid solution, resulting in the release of hydrogen with a volume of 6.72 liters. determine the mass fraction of copper in the mixture.

Copper does not react with sulfuric acid at room temperature.

Metallic aluminum interacts with sulfuric acid. In this case, aluminum sulfate is synthesized and hydrogen gas is released. The interaction is described by the following chemical equation.

2Al + 3H2SO4 = Al2 (SO4) 3 + 3 H2;

Let’s determine 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 = 6.72 / 22.4 = 0.3 mol;

To synthesize such an amount of gaseous hydrogen, it is necessary to take 0.3 x 2/3 = 0.2 mol of metallic aluminum.

Let’s find its mass.

For this purpose, we multiply the amount of the substance by the weight of 1 mole of this chemical element.

M Al = 27 grams / mol; m Al = 0.2 x 27 = 5.4 grams;

Determine the mass fraction of metallic aluminum:

K = 5.4 / 20 = 0.27 = 27%; The mass fraction of copper will be: 100 – 27 = 73%;