An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If Ti is the initial temperature and Tf is the final temperature, which of the following statements is correct?
Correct answer: D. (Tf)irrev > (Tf)rev
- A. Tf > Ti for reversible process but Tf = Ti for irreversible process.
- B. (Tf)rev = (Tf)irrev
- C. Tf = Ti for both reversible and irreversible processes
- D. (Tf)irrev > (Tf)rev
Explanation
In an isolated system, the expansion of an ideal gas occurs adiabatically, meaning no heat is exchanged with the surroundings (q = 0). For reversible processes, the work done is maximized, resulting in a greater decrease in internal energy and thus a lower final temperature compared to irreversible processes. Therefore, the final temperature after an irreversible expansion is higher than that after a reversible expansion.Option A is incorrect because the temperature change is not the same for reversible and irreversible processes. Option B is incorrect because the final temperatures are not equal due to different efficiencies in work done. Option C is incorrect because the expansion process induces a temperature change.
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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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