Problem: A 0.70 g sample of a weak monoprotic acid was dissolved in 150 mL of water and titrated with a 0.055 M solution of KOH at 25°C. At the half-equivalence point, after addition of 25.5 mL of the KOH solution, the pH was 3.8.What will the pH be at the equivalence point of the above titration?A. 7.60B. 6.03C. 7.97D.  2.83E. 11.17

FREE Expert Solution

We are being asked to calculate the pH at the equivalence point for titration of a weak monoprotic acid (HA) with a 0.055 M solution of KOH.


We will calculate the pH of the solution at the equivalence point using the following steps:

Step 1. Write the chemical equation for the reaction between HA and KOH.
Step 2. Calculate the initial amounts of HA and KOH in moles before the reaction happens.
Step 3. Construct an ICF Chart.
Step 4. Calculate the new concentration of the species left in the solution.
Step 5. Calculate pH.


Step 1. Write the chemical equation for the reaction between HA and KOH.

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Problem Details

A 0.70 g sample of a weak monoprotic acid was dissolved in 150 mL of water and titrated with a 0.055 M solution of KOH at 25°C. At the half-equivalence point, after addition of 25.5 mL of the KOH solution, the pH was 3.8.

What will the pH be at the equivalence point of the above titration?

A. 7.60

B. 6.03

C. 7.97

D.  2.83

E. 11.17

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Weak Acid Strong Base Titrations concept. You can view video lessons to learn Weak Acid Strong Base Titrations. Or if you need more Weak Acid Strong Base Titrations practice, you can also practice Weak Acid Strong Base Titrations practice problems.