During isothermal reversible compression of an ideal gas, which of the following occurs_______________?
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Answer: C. ΔE = ΔH = 0
Explanation
For an isothermal process involving an ideal gas, internal energy and enthalpy depend only on temperature, so change in internal energy and enthalpy equal zero. Constant temperature ensures that internal energy remains fixed for any ideal gas system. Since enthalpy is also purely temperature dependent for ideal gases, it experiences zero net variation. Isothermal processes occur at a strictly constant temperature managed by heat exchange with surroundings. Internal energy and enthalpy are state functions dependent solely on temperature for ideal gases. The first law requires that heat added during isothermal expansion equals the work done by the gas.
Slowly expanding a gas-filled piston submerged in a constant-temperature water bath exemplifies this process. Compressor staging calculations often evaluate isothermal compression limits to minimize work input. Thermodynamic cycle analysis frequently assumes isothermal heat addition or rejection steps. Only internal energy equals zero ignores the fact that ideal gas enthalpy is also temperature dependent. Only enthalpy equals zero neglects the fundamental temperature dependence of ideal gas internal energy. dQ equals dE describes internal energy balance without accounting for the zero change condition.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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