0.2 mol of ethylene was passed through bromine water. What is the mass of 1,2-dibromoethane obtained as a result of the reaction.

1. Let’s write down the reaction of addition of bromine to ethylene:
Br2 (H2O) + CH2 = CH2 → CH2 (Br) CH2 (Br);
2.the amount of ethylene reacted is comparable to the amount of dibromoethane obtained:
n (CH2 (Br) CH2 (Br)) = n (CH2 = CH2) = 0.2 mol
3. find the mass of dibromoethane:
m (CH2 (Br) CH2 (Br)) = n (CH2 (Br) CH2 (Br)) * M (CH2 (Br) CH2 (Br));
M (CH2 (Br) CH2 (Br)) = 12 * 2 + 4 * 1 + 80 * 2 = 188 g / mol;
m (CH2 (Br) CH2 (Br)) = 0.2 * 188 = 37.6 g.
Answer: 37.6 g.