Find the mass of benzene reacted with bromine if 15.7 g of bromobenzene is formed.

We carry out the solution:

In accordance with the condition, we compose the equation of the process:
C6H6 + Br2 = C6H5Br + HBr – substitutions, bromobenzene was obtained;

We make calculations:
M (C6H6) = 78 g / mol;

M (C6H5Br) = 156.9 g / mol;

Y (C6H5Br) = m / M = 15.7 / 156.9 = 0.1 mol;

Y (C6H6) = 0.1 mol since the amount of substances is 1 mol each, which is shown by the equation.

Find the mass of the product:
m (C6H6) = Y * M = 0.1 * 78 = 7.8 g

Answer: the mass of benzene is 7.8 g