Assume you dissolve 0.235 g of the weak acid benzoic acid, C6H5CO2H, in enough water to make 4.00*10^2 mL of solution and then titrate the solution with 0.138 M NaOH.
C6H5CO2H(aq) + OH-(aq) C6H5CO2-(aq) + H2O(l)
Find concentration of Na+ at equivalence point.