3. (16 pts) dS=TCVdT+(TP)VdVdS=TCPdT(TV)PdP (a) When a piston containing a real gas (a=0.1,b=0.9) is expanded from 1.00m3 to 1.25m3 isothermally, calculate entropy. Then, compare S for this real gas with S for ideal gas in the same expansion condition and comment on the difference of magnitudes. (b) Let's think the molecular interaction with the microstate-based statistical entropy. Say the microstate of ideal gas is expressed as Figure 1. To represent the condition of (a), do you choose Figure 2 or Figure 3 ? Use the condition that you have three molecules for the simplification. Without justification and calculation, you receive no credit. In addition, you must explain why the model of Figure 2 or Figure 3 fits with the molecular interaction you proposed in (a). Note that one ball occupies one hole regardless of the size of hole depicted 3bal1) boles! I chuose figio