Final answer:
The different internal energies of nitrogen, neon, and ozone at the same temperature are due to their molecular structures. Ozone has a higher internal energy because it has more degrees of freedom than mono- or diatomic gases. In an isothermal expansion, the internal energy change is zero and the heat absorbed equals the work done by the gas.
Step-by-step explanation:
When considering isothermal expansion of an ideal gas, the internal energy change (ΔU) is zero because temperature remains constant and, for an ideal gas, internal energy is a function of temperature alone.
However, different gases at the same temperature may have different internal energies due to differences in molecular structure and degrees of freedom.
Ozone, being a triatomic molecule, has more vibrational modes compared to diatomic nitrogen and monatomic neon, thus at a constant temperature such as 290K, ozone can possess more internal energy.
In an isothermal expansion, according to the first law of thermodynamics, ΔEint = Q - W, where Q is the heat added to the system and W is the work done by the gas.
Since the internal energy change is zero (ΔEint = 0), the heat absorbed (Q) is exactly equal to the work done (W) by the gas. Therefore, the internal energy of the gas does not change, and the process takes place at a constant temperature.