Final answer:
The titration combinations resulting in pH greater than 7 at the equivalence point are those involving a weak acid with a strong base, and a strong base with a weak acid. Specifically, the combinations b. (weak acid; strong base) and g. (strong base; weak acid) meet this criterion.
Step-by-step explanation:
Identifying titration combinations that result in pH greater than 7.00 at the equivalence point involves understanding the properties of strong and weak acids and bases.
In a titration, when a weak acid is the analyte and a strong base is the titrant, the pH at the equivalence point is greater than 7. This is due to the formation of a basic salt and excess hydroxide ions in the solution.
Conversely, when a strong acid is titrated with a weak base, the pH at the equivalence point will be less than 7 due to the formation of an acidic salt and excess hydrogen ions.
Additionally, when a strong base is the analyte and the titrant is a weak acid, the situation is reversed with an equivalence point pH greater than 7, resulting from a basic salt and residual weak acid that does not fully neutralize the strong base.
Similarly, a weak base titrated with a strong acid will also have a pH less than 7 at the equivalence point. Important to note is that the titration of a strong acid with a strong base (or vice versa) will have an equivalence point pH of exactly 7.00. This is due to the neutralization of the acid and base forming water and a neutral salt.
The combinations that typically produce pH greater than 7 at the equivalence point are therefore those involving a weak acid with a strong base, and a strong base with a weak acid. The correct answers to the question are:
- b. analyte = weak acid; titrant = strong base
- g. analyte = strong base; titrant = weak acid
Combination e. (analyte = weak base; titrant = weak acid) and f. (analyte = weak acid; titrant = weak base) could also potentially result in a pH > 7 depending on the specific strengths of the weak acid and weak base.
However, these combinations have unpredictable equivalence points and are not as straightforward as the clear-cut cases of a strong reaction partner with a weak one.