A student titrates a solution containing 0.050 moles of calcium hydroxide with phosphoric acid. How many moles of phosphoric acid need to be added to reach the equivalence point?

The answer to your question is 0.33 moles of H₃PO₄

Explanation:

Data

moles of Ca(OH)₂ = 0.050

moles of H₃PO₄ = ?

Process

1.- Write the balanced chemical equation

           3Ca(OH)₂  +  2H₃PO₄    ⇒   Ca₃(PO₄)₂   +   6H₂O

             Reactants        Elements       Products

                    3                      Ca                     3

                   12                       H                     12

                   14                      O                      14

2.- Calculate the moles of phosphoric acid

      3 moles of calcium hydroxide 2 moles of phosphoric acid

      0.5 moles of calcium hydroxide   x

      x = (0.5 x 2)/3

      x = 0.33 moles