I have recently been tackling a problem from one of my A-Level chemistry exercises on the topic of acids and bases, particularly with strong base and weak acid titration curves:

A titration is carried out in which $\pu{25 cm3}$ of $\pu{0.08 mol dm-3}$ propanoic acid $\ce{CH3CH2COOH}$ of pH 2.5 is put in a conical flask. Sodium hydroxide solution of concentration $\pu{0.1 mol dm-3}$ is added from a burette until $\pu{50 cm3}$ has been added.

One of the sub-questions asked to state the equivalence point of the pH, but I do not know whether drawing a rough sketch (as the exercise had suggested) would be validly sufficient to deduce this. From my reading of theoretically calculating such a point, a $\mathrm{K}_b$ constant is required such as that used in a solution in a similar conundrum: https://socratic.org/questions/calculate-the-ph-at-the-equivalence-point-for-the-titration-of-0-20-m-hcl-with-0 But the exercise does not provide such a value.

While the volume of the strong base, sodium hydroxide, required to reach the end-point is easy to calculate, as...

$\pu{0.1 mol dm-3} = \frac{\pu{2 * 10^-3 mol}}{v}$

$v = \pu{0.02 dm3} = \pu{20 cm3}$

...I am still unsure what would be the best way to tackle such a problem in which a roughly accurate answer could be obtained.



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