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Chapter 17: Problem 37

Predict whether the equivalence point of each of the following titrations is below, above, or at \(\mathrm{pH}\) 7: (a) \(\mathrm{NaHCO}_{3}\) titrated with \(\mathrm{NaOH},\) (b) \(\mathrm{NH}_{3}\) titrated with \(\mathrm{HCl}\) (c) KOH titrated with HBr.

Short Answer

Expert verified
For the titrations given: (a) NaHCO3 with NaOH will have an equivalence point with a pH above 7 due to a weak acid being titrated with a strong base. (b) NH3 with HCl will have an equivalence point with a pH below 7, as a weak base is being titrated with a strong acid. (c) KOH titrated with HBr will have an equivalence point with a pH at exactly 7, as both are strong species that balance each other out.

Step by step solution

01

Titration (a) NaHCO3 with NaOH

We have a bicarbonate (\(\mathrm{NaHCO}_{3}\)) being titrated with a strong base (\(\mathrm{NaOH}\)). Since bicarbonates are weak acids and \(\mathrm{NaOH}\) is a strong base, the equivalence point will occur when the pH is above 7 because the weak acid will be neutralized by the strong base, producing a basic solution at the equivalence point.
02

Titration (b) NH3 with HCl

We have a weak base (\(\mathrm{NH}_{3}\)) being titrated with a strong acid (\(\mathrm{HCl}\)). When the reaction is complete, the equivalence point will be reached. In this case, since we have a strong acid reacting with a weak base, the equivalence point will occur when the pH is below 7 because the strong acid will cause the solution to become acidic.
03

Titration (c) KOH with HBr

In this case, we have a strong base (\(\mathrm{KOH}\)) being titrated with a strong acid (\(\mathrm{HBr}\)). When the reaction is complete and the equivalence point is reached, these two strong species will balance each other, resulting in a neutral solution. Therefore, the pH at the equivalence point will be exactly 7.

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Most popular questions from this chapter

Derive an equation similar to the Henderson-Hasselbalch equation relating the \(\mathrm{pOH}\) of a buffer to the \(\mathrm{p} K_{b}\) of its base component.

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