Question

Calculate the pH at the equivalence point in titrating 0.100 M solution of Benzoic Acid (C6H5COOH) with 0.800 M NaOH.

Answer 1

# calculation of pH at the equivalence point A Titration of 0.100 M benzoic acid with 0.800 M NaOH. At the equivalance point acid is completely neetrallised and the resulting product is salt (46 H15 Goona). After that sait Hydrolysis starts C6H5 COOH + Nach - > CG HE COONa + H20 salt) . (water) Hydrolysis, of Saits: C6H5 COONa + H2O --> CHE COUH + NaOH . We can calculate the pH at equiralance point by Using the formula, DH = Ź pkw + Ź pka + { log salt] If we take 40 mL 0.100M Benzoic acid Then, Vi so = V2 S2 or 40 X 0.100 = V2 X 0.800 ar V2 = 5ML

30 equivalance point come when we add 5 mL O: 800 M NACH solution to the 40 mL O 100 M Benzoic and solution A. Now, total volume of the solution = (40+5)= 45 mL Amount of salt formed = 5 mL X0.800 M . = 4 milimole. i concentration of salt = 4 milimole 45mL = 0.0889 m opka of benzoic acid = 4.20 Þkw = 14 = ÞH + bort . ÞH at equivallance point → ÞH = { pkw + Ź pka + Ź log [salt] - x14 + £*4.20 + Ž 109 (0.0889] = 7+ 2110 + (-0.525) = 8:57 . PH at equivalence point = 8:57 FOR we take 40 mL Do 100 m Benzoic acid? A In the question amount of benzoic acid is not mentioned, I take 40 mL as to calculate equivalance point I need the amount of benzoic acid used

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