Enthalpy is a state function. Standard enthalpy change is measured at:
Correct answer: C. 298K
- A. 270K
- B. 200K
- C. 298K
- D. 273K
Explanation
The correct option for the temperature at which the standard enthalpy change is measured is C) 298K (Kelvin). This is the most commonly used temperature for standard conditions in thermochemistry. Standard enthalpy change (ΔH°) is typically measured at a standard temperature of 298.15 Kelvin (25 degrees Celsius or 77 degrees Fahrenheit). This standard temperature is often used in thermochemical calculations to provide a consistent reference point for measuring enthalpy changes, particularly in chemical reactions. The standard enthalpy change is often expressed in units of kilojoules per mole (kJ/mol) or calories per mole (cal/mol).
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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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