A32.00 ml sample of an unknown h3po4 solution is titrated with a 0.110 m naoh solution. the equivalence point is reached when 28.23 ml of naoh solution is added.
what is the concentration of the unknown h3po4 solution?

You first of all need to write a balanced chemical equation for the reaction of sodium hydroxide and phosphoric acid. You know that you have 0.110 M and 0.02823 L of sodium hydroxide. You multiply 0.110 M times 0.02823 L to get 0.0311 mol of sodium hydroxide and then you multiply by the mol ratio of 1 mol of phosphoric acid to 3 mol of sodium hydroxide to get the mol of phosphoric acid. You then divide 0.00104 mol of phosphoric acid by 0.03200 L to get 0.0325 M.

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