ΔH° represents the enthalpy changeat standard conditions, which are:
Correct answer: C. 25°C and 1 atm pressure
- A. 0°C and 1 atm pressure
- B. 0 K and 1 atm pressure
- C. 25°C and 1 atm pressure
- D. 25°C and 2 atm pressure
Explanation
The symbol "°" denotes standard conditions in thermodynamics. For thermochemical data, this is almost universally defined as a pressure of 1 atm (or 1 bar) and a temperature of 25°C (298.15 K).
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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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