Problem 2
A monatomic ideal gas of n moles at fixed absolute temperature T is confined by a frictionless piston. It expands slowly and reversibly from V₁ to V₂>V₁, remaining in thermal equilibrium with a reservoir at T; R is the gas constant. (a) Write the equation of state and calculate work done by the gas. (b) Find ΔU and heat Q absorbed, taking work by the gas as positive. (c) Explain why ΔU is independent of atomic species in this isothermal process. Use SI units throughout and treat components as ideal exactly as specified. State sign conventions when writing equations and retain units in final results.
problems.proof.stepOf
problems.proof.analysis
The next part uses the preceding result as input rather than treating parts independently. This keeps conventions and physical state consistent throughout.
problems.proof.pitfall. Pitfall: do not change sign conventions between equations; a negative sign may encode direction rather than an invalid result.