For each of the four cases below, determine whether there exists an ideal gas pr

Question

For each of the four cases below, determine whether there exists an ideal gas process that satisfies the given conditions. If so, describe an experiment (e.g., one involving a cylinder sealed with a movable, frictionless piston) that is consistent with the given conditions. If not, explain how you know that such a process does not exist. a. There is heat transfer, but the temperature of the gas does not change. b. There is no heat transfer, but the temperature of the gas changes. c. There is no heat transfer, but work is done on the gas. d. There is heat transfer, but no work is done on the gas.

Explanation / Answer

Be careful by saying "T is non-zero" or "T is zero". It isn't temperature itself that can or cannot be zero...it is CHANGE in temperature that might or might not be zero. Temperature itself MUST be greater than absolute zero in any real situation. So you need to call this "deltaT" and not just T. The same is true for internal energy U.


1. An isothermal reversible expansion of a gas. All heat added becomes work done as the gas decreases in pressure.

2. Any adiabatic and reversible process of a gas, consider an adiabatic expansion. The system is well insulated or happens faster than heat transfer timescales. All work done by the gas comes from its decrease in internal energy, thus corresponding to a decrease in temperature.

3. An adiabatic compression of a gas. The system is well insulated or happens faster than heat transfer timescales. All work done on the gas becomes an increase in internal energy and thus an increase in temperature.

4. Any isochoric (constant volume) process, heating or cooling. Think of it occuring in a rigid vessel. In the case of ischoric heating, heat is added to the system and all of it becomes internal energy, thus increasing temperature and also pressure.

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