What is the pH at the equivalence point of the titration in the previous problem?
A. 2
B. 5.7
C. 7.0
D. 8.3
D
The titration is between a weak acid and a strong base, so the expected pH is in the basic range. At the equivalence point, all of the hydrogen ions from the dissociation of HCN have been neutralized. However, is a strong base and attracts hydrogen ions from water molecules. This reaction is given by the following equation.
The resulting hydroxide ions make the solution basic. The concentration of the hydroxide ions must be found first. At the equivalence point, the concentration of the hydronium ions resulting from the dissociation of HCN is the same as the concentration of the ions. This value was determined in problem 79 to be This information, with
