Indicate how much chlorine is needed to obtain 129 g of chloroethane.

Given:
m (C2H5Cl) = 129 g

To find:
V (Cl2) -?

Solution:
1) Write the reaction equation:
C2H6 + Cl2 => C2H5Cl + HCl;
2) Calculate the molar mass of C2H5Cl:
M (C2H5Cl) = Mr (C2H5Cl) = Ar (C) * N (C) + Ar (H) * N (H) + Ar (Cl) * N (Cl) = 12 * 2 + 1 * 5 + 35, 5 * 1 = 64.5 g / mol;
3) Calculate the amount of C2H5Cl substance:
n (C2H5Cl) = m (C2H5Cl) / M (C2H5Cl) = 129 / 64.5 = 2 mol;
4) Determine the amount of substance Cl2:
n (Cl2) = n (C2H5Cl) = 2 mol;
5) Calculate the volume of Cl2:
V (Cl2) = n (Cl2) * Vm = 2 * 22.4 = 44.8 liters.

Answer: The volume of Cl2 is 44.8 liters.