The enthalpies of free elements in their standard states are
Correct answer: B. Zero
- A. Unit
- B. Zero
- C. < zero
- D. Between Zero and one
Explanation
The enthalpies of free elements in their standard states are defined as zero. This is because the enthalpy change associated with the formation of an element from its most stable form in its standard state is considered to be zero by convention. This serves as a reference point for measuring the enthalpy changes of chemical reactions.
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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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