Which statement is not correct about ∆H°?
Correct answer: D. ∆H° is always < 0
- A. ∆H° of the reaction depends on temperature
- B. ∆H° of reaction can be > or < zero
- C. ∆H° of catalyzed and uncatalyzed reaction is the same
- D. ∆H° is always < 0
Explanation
This statement is false. The standard enthalpy change (∆H°) can be positive for endothermic reactions (which absorb heat) or negative for exothermic reactions (which release heat). It is not always negative.
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About Thermochemistry and Energetics of Chemical Reactions
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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