When a system is taken from state a to state b in ?Fig. P19.37 along path ?acb?, 90.0 J of heat flows into the sys-tem and 60.0 J of work is done by the system. (a) How much heat flows into the system along path ?adb if the work done by the system is 15.0 J? (b) When the system is returned from b to a along the curved path, the absolute value of the work done by the system is 35.0 J. Does the system absorb or liberate heat? How much heat? (c) If Ua = 0 and Ud = 8.0 J, find the heat absorbed in the processes ?ad? and ?db?.

Solution 41P This question is based on the first law of thermodynamics, which is expressed mathematically as Q = U + W , where Q is the amount of heat added to a system, U is the change in internal energy of the system and W is the work done by the system. Given that, along path acb, Q = 90.0 J W = 60.0 J Therefore, along the path acb, the change in internal energy is U) acb= Q W = 90.0 60.0 J = 30.0 J (a) Along the path adb also, the change in internal energy is also 30.0 J. Given, W) adb= 15.0 J Therefore, the heat flow along the path adb is Q) adb= W) adb + U) adb= 15.0 J + 30.0 J = 45.0 J (b) When the system returns from b to a, there is a decrease in volume of the system, therefore W) ba = 35.0 J . The change in internal...