Calculate the mass of 5% bromine water required to obtain 11.28 g of dibromoethane.

1. Let us write the equation for the reaction of bromine water with ethene:

C2H4 + Br2 → C2H4Br2;

2.Calculate the chemical amount of dibromoethane:

n (C2H4Br2) = m (C2H4Br2): M (C2H4Br2);

M (C2H4Br2) = 2 * 12 + 4 + 2 * 80 = 188 g / mol;

n (C2H4Br2) = 11.28: 188 = 0.06 mol;

3. Determine the amount and find the mass of bromine:

n (Br2) = n (C2H4Br2) = 0.06 mol;

m (Br2) = n (Br2) * M (Br2) = 0.06 * 160 = 9.6 g;

4.calculate the mass of bromine water:

m (Br2 (H2O)) = m (Br2): w (Br2) = 9.6: 0.05 = 192 g.

Answer: 192 g.