An analytical chemist is titrating of a solution of benzoic acid with a solution of . The of benzoic acid is . Calculate the pH of the acid solution after the chemist has added of the solution to it. Note for advanced students: you may assume the final volume equals the initial volume of the solution plus the volume of solution added.

The question is incomplete. The complete question is :

An analytical chemist is titrating 148.9 mL of a 1.100 M solution of benzoic acid  with a 0.3600 M solution of KOH. The  of benzoic acid is 4.20. Calculate the pH of the acid solution after the chemist has added 232.0 mL of the KOH solution to it. Note for advanced students: you may assume the final volume equals the initial volume of the solution plus the volume of KOH solution added.

Solution :

Number of moles of

                                                         = 0.16379 mol

Number of moles of NaOH added

                                                         = 0.08352 mol

ICE table :

I (mol)              0.16379                 0.08352              0

C (mol)           -0.08352              -0.08352            +0.08352

E (mol)            0.08027                    0                    0.08352

Total volume = (148.9 + 232) mL

                      = 380.9 mL

                     = 0.3809 L

Concentration of

                                                                               = 0.211 M

Concentration of

                                                                              = 0.219 M

of

According to Henderson equation,

     = 4.22

Therefore, the pH of the acid solution is 4.22

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