Column I contains some chemical reactions and Column II contains some ΔH values (in kJ). Match the correct ΔH in Column II for the chemical reaction in Column I, with the help of the following thermoc

Question

Column I contains some chemical reactions and Column II contains some ΔH values (in kJ). Match the correct ΔH in Column II for the chemical reaction in Column I, with the help of the following thermochemical equations given:
H+(aq) + OH-(aq) → $H_2O$(l); ΔH = -57.3 kJ
ΔH_solution of HA(g) = -70.7 kJ/mol
ΔH_solution of BOH(g) = 20 kJ/mol
ΔH_ionization of HA = 15 kJ/mol and BOH is a strong base.

Column I (Chemical reactions):
(A) HA(aq) + BOH(aq) → BA(aq) + $H_2O$
(B) HA(g) + BOH(g) → BA(aq) + $H_2O$
(C) HA(g) → H+(aq) + A-(aq)
(D) B+(aq) + OH-(aq) → BOH(aq)

Column II (ΔH values in kJ):
(P) -42.3
(Q) -93
(R) -55.7
(S) 0

Prashant Kotian · Accepted Answer

Correct answer: A→P; B→Q; C→R; D→S. (A) Weak acid ionization (+15 kJ/mol) + neutralization (-57.3 kJ/mol) = -42.3 kJ (P).
(B) Sum of dissolution enthalpies and neutralization: -70.7 + 20 - 42.3 = -93 kJ (Q).
(C) Dissolution of gaseous HA (-70.7) and ionization (+15) = -55.7 kJ (R).
(D) Strong base is completely dissociated, so ion association enthalpy change is 0 (S).

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