CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A 50.00 mL sample of 0.200 M pyridine, C5H5N (Kb=1.5×10−9), is titrated at 25 °C with 0.500 M nitric acid. When 21.0 mL of the acid has been added, the solution is beyond the equivalence point by a small margin.
(a) Calculate the number of moles of reactants initially present and identify which reagent is in excess after reaction.
(b) Compute the molarity of the excess reagent in the final solution, accounting for dilution.
(c) Determine the pH of the solution at this stage of the titration.
(d) Justify whether the conjugate acid, C5H5NH+, has a significant influence on the calculated pH at this post-equivalence volume.