Question

Calculate the pH at the equivalence point when 40.0 mL of 0.100 M benzoic acid is titrated with 40.0 mL 0.100 M NaOH.   
  
HC₇H₅O₂(aq)     + H₂O (l)              C₇H₅O₂^-(aq)     + H₃O⁺(aq)           K_a = 6.3 x 10 ^-5

A. 9.17

B. 3.22

C. 4.97

D. 10.1

E. 8.45

F. 9.00

G. 7.96

H. 6.07

Answer 1

Hope this solution will help you.

Solutions - 40.0 mL of o.loom benzoic acid will completely reacts with 400mL of 0.10om NaOH. It will form Co Heco ion, or cohe CO₂ Na type salt. It is salt of weak acid and strong base . PM for this type of salt is given by Py = ₃ [ Pika + Pkw + loge] here motes of benzoic acid = 0.1X40 & final concentration of salt is 0.1 X 406 = 0.05m. now, Pr = 1 [4.2 +14 & 10g (0:05) = 8.45. 1000 x 80

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