4.1 Zero if reversible.
4.5 (a) (AS)a = 23.5 J K-1, (b) (AS)b = 120.6 J K-1, (c) (AS)c = 8.6JK-1.
4.6 (b) V2 = 3.44m3, T2 = 227K, (c) AH = -146.7kJ, AU = -104.7kJ, (d) W = 104.7 kJ.
4.7 (a) p2 = 37877Pa, W2 = -65.2kJ, (b) W1 = 104.7kJ, W2 = -65.2 kJ, Wtot = 39.5 kJ, (c) T3 = 113.6 K, (AS)2 = 1.39 kJK-1.
4.8 Use the isotherm joining the beginning and end points. AS = 199JK-1. AU = AH = 0.
4.9 Both zero for the cycle, if it is reversible. Tmax is at the point A. Tmin is at the opposite point on the circle.
4.10 Sliding up and down an isotherm in the T - S diagram encloses no area. 4.14 -19.2 kJ.
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