Question

Consider the curve shown here for the titration of a weak base with a strong acid and answer each question. 

a. What is the pH and what is the volume of added acid at the equivalence point? 

b. At what volume of added acid is the pH calculated by working an equilibrium problem based on the initial concentration and Ks of the weak base? 

c. At what volume of added acid does pH = 14 - pka ? 

d. At what volume of added acid is the pH calculated by working an equilibrium problem based on the concentration and K, of the conjugate acid? 

e. Beyond what volume of added acid is the pH calculated by focusing on the amount of excess strong acid added? 

Problem 2: 

Consider the titration of a 35.0 mL sample of 0.175 M HBr with 0.200 M KOH. 

Determine each quantity. 

a. the initial pH 

b. the volume of added base required to reach the equivalence point 

c. the pH at 10.0 mL of added base 

d. the pH at the equivalence point 

e. the pH after adding 5.0 mL of base beyond the equivalence point 

Problem 3: 

Draw the titration curve for the above titration using the points you calculated above

Answer 1

The values ​​are read in the graph:

a) The pH at the equivalence point is 6. A volume of 25 mL is required for the equivalence point.

b) When no amount of acid has been added, it is when the pH is calculated based on the concentration of the base and the Kb.

c) The volume of acid in which pH = 14 - pKb = pKa, is at the midpoint of equivalence, is 12.5 mL

d) From the first drop of acid and until before the equivalence point, the pH is calculated using equilibrium and Ka.

e) After the equivalence point, the pH is determined by the excess of strong acid (After 25 mL).

If you liked the answer, please rate it in a positive way, you would help me a lot, thank you.