Enthalpy of the reaction: Ag + (aq) + Br - (aq) → AgBr(s) is -84.54 kJ. Magnitude of enthalpies of formation of Ag + (aq) and Br - (aq) is in 8:9 ratio but their signs are opposite. Enthalpy of format

Question

Enthalpy of the reaction: Ag + (aq) + Br - (aq) → AgBr(s) is -84.54 kJ. Magnitude of enthalpies of formation of Ag + (aq) and Br - (aq) is in 8:9 ratio but their signs are opposite. Enthalpy of formation of AgBr is -99.54 kJ/mol. The magnitude of enthalpy of formation of Ag + (aq) (in kJ/mol) is

TestHub · Accepted Answer

Let Δ H f (Ag + ) = 8k and Δ H f (Br - ) = -9k. (The other sign choice yields k = -15, which is not allowed.) The enthalpy change for the reaction, Δ H rxn , is given by: Δ H rxn = Δ H f (AgBr) - Δ H f (Ag + ) - Δ H f (Br - ) Substituting the given values: -84.54 = -99.54 - (8k - 9k) -84.54 = -99.54 + k Solving for k: k = -84.54 + 99.54 k = 15 The magnitude of Δ H f (Ag + ) is 8 × 15 = 120 kJ/mol. Thus, the answer is 0120.

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