Calculate the mass of a given volume of gas and its amount of substance Cl2 gas; V = 5.6 liters.

Given:
V (Cl2) = 5.6 L
Vm = 22.4 l / mol

Find:
m (Cl2) -?
n (Cl2) -?

1) Calculate the amount of chlorine substance:
n (Cl2) = V (Cl2) / Vm = 5.6 / 22.4 = 0.25 mol;
2) Using the periodic system of D.I.Mendeleev, calculate the molar mass of chlorine:
M (Cl2) = Mr (Cl2) = Ar (Cl) * N (Cl) = 35.5 * 2 = 71 g / mol;
3) Calculate the mass of chlorine:
m (Cl2) = n (Cl2) * M (Cl2) = 0.25 * 71 = 17.75 g.

Answer: The mass of Cl2 is 17.75 g; the amount of substance is 0.25 mol.