Titrations of Diprotic and Polyprotic Acids Video Lessons

Concept

# Problem: The pKb values for the dibasic base B are pKb1 = 2.1 and pKb2 = 7.5. Calculate the pH at each of the following points in the titration of 50.0 mL of a 0.95 M B(aq) with 0.95 M HCl(aq).(d) after addition of 75.0 mL of HCl (e) after addition of 100.0 mL of HCl

###### FREE Expert Solution

We're being asked to calculate the pH at each of the following points in the titration of 50.0 mL of a 0.95 M B(aq) with 0.95 M HCl(aq):

Recall molarity:

Reaction @ 1st equivalence point: B(aq) + HCl(aq) → HB+(aq) + Cl-(aq)

Reaction @ 2nd equivalence point: HB+(aq) + HCl(aq) → H2B2+(aq) + Cl-(aq)

Overall reaction: B(aq) + 2 HCl(aq) → H2B2+(aq) + 2 Cl-(aq)

Calculate the volume of HCl required to reach 1st equivalence point:

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###### Problem Details

The pKb values for the dibasic base B are pKb1 = 2.1 and pKb2 = 7.5.

Calculate the pH at each of the following points in the titration of 50.0 mL of a 0.95 M B(aq) with 0.95 M HCl(aq).

(d) after addition of 75.0 mL of HCl

(e) after addition of 100.0 mL of HCl