Answer: Enthalpy change at different temperatures.
- A Gibbs energy at different temperatures
- B Enthalpy change at different temperatures
- C Entropy at absolute zero
- D Activation energy
Correct answer: B. Enthalpy change at different temperatures
Explanation: Kirchhoff's equation accounts for how ΔH varies with temperature based on heat capacity differences (ΔCp).
Isothermal expansion follows a gentler curve (heat flows in to keep T constant) while adiabatic expansion drops in pressure more steeply (no heat exchange, so internal energy and temperature fall as the gas does work).
Concept context
Study energy changes in chemical reactions. Understand enthalpy, entropy, Gibbs free energy, and the laws of thermodynamics that decide whether a reaction will occur spontaneously or not.