Question

You are titrating a 7 0 0 ml sample of 0 . 1 5 m ccl ₃ cooh ( pka = 0 . 6 6 ) with 0 . 2 m naoh. what will the ph be at the equivalence point?

Answer 1

The pH at the equivalence point of the titration between CCL₃COOH and NaOH is calculated using the pKa of the weak acid and the Henderson-Hasselbalch equation, resulting in a pH greater than 7 due to the basic nature of the trichloroacetate ion.

Step-by-step explanation:

To calculate the pH at the equivalence point of a titration involving the weak acid trichloroacetic acid (CCL₃COOH) with a strong base (NaOH), you must consider the properties of the resultant anion, which in this case is the trichloroacetate ion (CCL₃COO-). As CCL₃COOH is a weak acid, it does not dissociate completely in water, but its conjugate base, the trichloroacetate ion, will partially react with water in a hydrolysis reaction to produce hydroxide ions (OH-) and weak acid (CCL₃COOH).

At the equivalence point, the moles of CCL₃COOH originally present will be equal to the moles of NaOH added, and all the CCL₃COOH will be converted into CCL₃COO-. You would use the provided pKa value to determine the pKb of the conjugate base and then apply the Henderson-Hasselbalch equation to calculate the pH. The pH at the equivalence point will be greater than 7 because the resulting solution is slightly basic due to the hydrolysis of the conjugate base.