Answer: w = -nRT ln(V₂/V₁).
- A w = nRT ln(V₂/V₁)
- B w = -nRT ln(V₂/V₁)
- C w = PΔV mainly
- D w = Zero usually
Correct answer: B. w = -nRT ln(V₂/V₁)
Explanation: w = -nRT ln(V₂/V₁). For expansion V₂ > V₁, the system does work on surroundings (work done on system is negative).
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.