# During the electrolysis of a potassium chloride melt at the cathode, a metal with a mass of 78 g

**During the electrolysis of a potassium chloride melt at the cathode, a metal with a mass of 78 g was obtained, find the volume of released chlorine at the anode.**

Let’s find the amount of potassium substance by the formula:

n = m: M.

M (K) = 39g / mol.

n = 78 g: 39 g / mol = 2 mol.

Let’s compose the reaction equation for electrolysis of potassium chloride melt, find the quantitative ratios of substances.

2 KCl → 2K + Cl2.

According to the reaction equation, there is 1 mol of chlorine for 2 mol of potassium. Substances are in quantitative ratios of 2: 1.

The amount of chlorine will be 2 times less than the amount of potassium.

½ n (Cl2) = n (K) = 2: 2 = 1 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 = 1 mol × 22.4 L / mol = 22.4 L.

Answer: V = 22.4 liters.