A mixture contains 9.4 g of phenol and 10.8 g of 4-methylphenol. It is treated with excess bromine water. Assume every ring position ortho or para to the $- OH$ group that is free is replaced by one Br atom and that no oxidation occurs. Using atomic masses H = 1, C = 12, O = 16 and Br = 80, find the mass of $Br X_{2}$ consumed, in g (nearest integer).

Numerical answer type, tolerance 0.5.

Answer: 80

Molar masses: phenol 94, 4-methylphenol 108, so the amounts are 0.10 mol and 0.10 mol. Phenol gives 2,4,6-tribromophenol (3

Br X_{2}

per mol); 4-methylphenol has only two free positions (2 and 6) and gives 2,6-dibromo-4-methylphenol (2

Br X_{2}

per mol). Moles of

Br X_{2}

= 3(0.10) + 2(0.10) = 0.50 mol, mass = 0.50 x 160 = 80 g.