Consider a quasistatic isothermal expansion of an ideal gas from Va ---> Vb at temperature Th. If the heat transfer into the gas is (P1)(Va)ln(Vb/Va), determine the change in entropy of the gas for this process.

Write the expression of heat for an isothermal reversible expansion of a perfect gas from initial volume V1 to final volume V2.

Two different piston – cylinder devices each contain 1 kg of air. Initially, the temperature T = 300 K and %3D pressure P= 100 kPa of the gases are both the same in both cylinders. However, one of the cylinders is insulated and the other is not. Now, both of these gases inside the cylinders are let to expand in quasi- equilibrium processes until their pressures reach to 50 kPa. The expansion process takes place isentropically in the cylinder 1 and in the cylinder 2 the expansion process takes place reversible and isothermally. a) Plot in Excel the P-V diagrams of both processes. (Take k = cp / cv = 1.4) %3D b) Calculate the work done by the gases.

A mass flowrate of 1 Ibm/s of water at 80 F and 70 pisa is mixed with 1 Ibm/s of saturated vapor water at 70 psia in a mixing chamber. During this process 100 Btu/s of heat is lost from the mixing chamber to the surrounding environment. The exiting stream leaves the mixing chamber at 70 psia. In the question that follows, select the answer that is closest to the true value. What is the quality of the exiting stream ?