Question

Compare the change in internal energy of an ideal gas for a quasi-static adiabatic expansion with that for a quasi-static isothermal expansion. What happens to the temperature of an ideal gas in an adiabatic expansion?

a) ΔUadiabatic > ΔUisothermal; Temperature decreases
b) ΔUadiabatic < ΔUisothermal; Temperature increases
c) ΔUadiabatic = ΔUisothermal; Temperature remains constant
d) ΔUadiabatic = ΔUisothermal; Temperature changes unpredictably

Answer 1

In an adiabatic expansion of an ideal gas, the internal energy decreases and the temperature decreases, while in an isothermal expansion, the internal energy remains the same and the temperature remains constant.

Step-by-step explanation:

In an adiabatic expansion of an ideal gas, the internal energy decreases and the temperature decreases. This is because no heat is allowed to enter or leave the system during the expansion. The work done by the gas in the expansion is reflected in the lowering of its energy and temperature.

In contrast, in an isothermal expansion of an ideal gas, the internal energy remains the same and the temperature remains constant. This is because heat flow into the system counteracts the work done by the gas, resulting in no change in internal energy or temperature.

Therefore, the correct answer is:

b) ΔUadiabatic < ΔUisothermal; Temperature increases