In 200 g of a 15% phenol solution, 12 g of sodium hydroxide was added. Calculate the mass of the sodium phenolate formed.

Reaction of sodium phenolate formation.
C6H5OH + NaOH = C6H5ONa + H2O.
The mass of phenol contained in the solution.
m (C6H5OH) = W (C6H5OH) • m (solution) / 100% = 15% • 200 g / 100% = 30 g.
Determine the number of moles of reagents.
n (C6H5OH) = m / Mr = 30 g / 94 g / mol = 0.32 mol.
n (NaOH) = 12 g / 40 g / mol = 0.3 mol.
The calculation of the mass of sodium phenolate is carried out according to the lack of sodium hydroxide.
m (С6H5ONa) = n • Mr = 0.3 mol • 116 g / mol = 34.8 g.