Question

Consider the titration of 40.0 mL of 0.153-M of KX with 0.155-M HCl. The pK_a of HX = 5.84. Give all pH values to 0.01 pH units.

a) What is the pH of the original solution before addition of any acid?

pH =

b) How many mL of acid are required to reach the equivalence point?

V_A =  mL

c) What is the pH at the equivalence point?

pH =

d) What is the pH of the solution after the addition of 13.8 mL of acid?

pH =

e) What is the pH of the solution after the addition of 47.4 mL of acid?

pH =

Answer 1

* In part d and e when acid is added to the solution become acidic and pH decreases and as the pH decreases concentration of H+ ion increases.
so, concentration of H+ = volume of added acid * concentration of acid/ total volume of solution
total volume of solution = volume of KX + volume at equivalence point + volume of acid added