Question

In this case, the inflection point, and
equivalence, occurs after 23.25mL of 0.40 M NaOH has been delivered.
Moles of base at the equivalence point can be determined from the volume of base delivered to
reach the equivalence point and the concentration of NaOH.

1. Calculate the moles of NaOH added to reach the equivalence point (i.e. after the addition
of 23.25 mL of 0.40 M NaOH).

2. Using the fact that the acid and base are in exact stoichiometric proportions at the
equivalence point, calculate the moles of citric acid in the solution. The balanced
equation is:
H3C6H5O7(aq) + 3 NaOH(aq) -----> Na3C6H5O7(aq) + 3H2O(l)

3. calculate the mass of citric acid in the drink mix.

Answer 1

1) moles = moles x L.
2) moles NaOH x (3 moles citric acid/1 mole NaOH = moles citric acid.
3). mass citric acid = moles x molar mass.