Hydrogen peroxide in aqueous solution decomposes by a first-order reaction to water and oxygen. The rate constant for this decomposition is 7.50 × 10^-4 s^-1. What quantity of heat (in J) is initially

Question

Hydrogen peroxide in aqueous solution decomposes by a first-order reaction to water and oxygen. The rate constant for this decomposition is 7.50 × 10^-4 s^-1. What quantity of heat (in J) is initially liberated per second from 2.0 l of solution that is 0.02 M H2O2? Given ΔfH of H2O2(l) = -187.0 kJ/mol and ΔfH H2O(l) = -287.0 kJ/mol.

Prashant Kotian · Accepted Answer

Correct answer: 3. Reaction: H2O2(aq) → H2O(l) + 1/2 O2(g). ΔH_rxn = -287.0 - (-187.0) = -100 kJ/mol. Initial rate of decomposition = k[H2O2] × V = 7.50 × 10^-4 s^-1 × 0.02 mol/L × 2.0 L = 3.0 × 10^-5 mol/s. Heat liberated per second = Rate × ΔH_rxn = 3.0 × 10^-5 mol/s × 100,000 J/mol = 3.0 J/s. Therefore, correct answer is 3.

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