15. A rate constant k1 increases from 1.2 × 10⁻³ s⁻¹ at 300 K to 4.8 × 10⁻³ s⁻¹ at 330 K. Assuming Arrhenius behavior, the activation energy Ea is closest to: (A) 9.5 kJ mol⁻¹ (B) 19 kJ mol⁻¹ (C) 38 kJ mol⁻¹ (D) 76 kJ mol⁻¹ (E) 150 kJ mol⁻¹

2. For a reaction at constant pressure, the standard Gibbs energies at two temperatures are: ΔrG°(298K) = −12.0 kJ mol⁻¹, ΔrG°(348K) = −5.0 kJ mol⁻¹. Using the Gibbs-Helmholtz equation:what can be concluded about the sign of ΔrH°? (assuming that ΔrH° does not depend on T) (A) ΔrH° = 0 (B) ΔrH° ＞ 0 (endothermic) and ΔrH° is around +54 kJ mol⁻¹ (C) ΔrH° ＜ 0 (exothermic) (D) Cannot be inferred from ΔrG°(T) (E) ΔrH° ＞ 0 (endothermic) and ΔrH° is around +5.4 kJ mol⁻¹

15. A rate constant k1 increases from 1.2 × 10⁻³ s⁻¹ at 300 K to 4.8 × 10⁻³ s⁻¹ at 330 K. Assuming Arrhenius behavior, the activation energy Ea is closest to:
(A) 9.5 kJ mol⁻¹
(B) 19 kJ mol⁻¹
(C) 38 kJ mol⁻¹
(D) 76 kJ mol⁻¹
(E) 150 kJ mol⁻¹

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