18.8 g of phenol was treated with sufficient bromine water. Calculate the mass of precipitated sediment.

Given:
m (C6H5OH) = 18.8 g

To find:
m (draft) -?

Decision:
1) C6H5OH + 3Br2 => C6H2Br3OH ↓ + 3HBr;
2) M (C6H5OH) = Mr (C6H5OH) = Ar (C) * 6 + Ar (H) * 6 + Ar (O) = 12 * 6 + 1 * 6 + 16 = 94 g / mol;
M (C6H2Br3OH) = Mr (C6H2Br3OH) = Ar (C) * 6 + Ar (H) * 3 + Ar (Br) * 3 + Ar (O) = 12 * 6 + 1 * 3 + 80 * 3 + 16 = 331 g / mol;
3) n (C6H5OH) = m (C6H5OH) / M (C6H5OH) = 18.8 / 94 = 0.2 mol;
4) n (C6H2Br3OH) = n (C6H5OH) = 0.2 mol;
5) m (C6H2Br3OH) = n (C6H2Br3OH) * M (C6H2Br3OH) = 0.2 * 331 = 66.2 g.

Answer: The mass of C6H2Br3OH is 66.2 g.