At 25 ° C the enthalpy change, for the ionization of trichloroacetic acid is + 6.3 k J m o l - 1 and the entropy change, is + 0.0084 k J m o l - 1 K - 1 . Then p K a of tricholoro acetic acid is

Question

At 25 ° C the enthalpy change, for the ionization of trichloroacetic acid is + 6.3 k J m o l - 1 and the entropy change, is + 0.0084 k J m o l - 1 K - 1 . Then p K a of tricholoro acetic acid is, 1.74, 2.52, 0.66, 4.72

MARKS App · Accepted Answer

Δ G ° = Δ H ° - T Δ S ° Δ G ° = 6.3 - ( 298 × 0.0084 ) = 3.8 K J . m o l - 1 ∴ Δ G o = 2.303 RTlnK l o g K e q = l o g K a = - p K a = - Δ G ° 2.303 R T - p K a = - Δ G ° 2.303 R T = 3.8 2.303 × 0.008314 × 298 = 0.66

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