What is not correct about ΔHf (enthalpy of formation)?
Correct answer: B. It is always negative
- A. Its value gives an idea about the relative stability of reactants and the products
- B. It is always negative
- C. Its value depends upon the nature of bonds
- D. Its value may be negative or positive
Explanation
The enthalpy of formation (ΔHf ) can be either negative (exothermic, for stable compounds) or positive (endothermic, for unstable compounds). The statement that it is always negative is incorrect.
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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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