1. The initial state of one mole of a monatomic ideal gas is P=10 atm and T=300K. Calculate the change in the entropy of the gas for (a) an isothermal decrease in the pressure to 5 atm; (b) a revisible adiabatic expansion to a pressure of 5 atm; (c) a constant-volume decrease in the pressure to 5 atm.

2. one mole of a monatomic ideal gas is subjected to the following sequence of steps:

a. starting at 300 K and 10 atm, the gas expands freely into a vacuum to triple its volume.

b. The gas is next heated reversibly to 400 K at constant volume.

c. The gas is reversibly expanded at constant temperature until its volume is again tripled.

d. The gas is finally reversibly cooled to 300 K at constant pressure.

Calculate the values of q and w and the changes in U, h and S.

3.Calculate the change in the enthalpy and the change in entropy when one mole of SiC is heated from 25 degree Celcius to 1000 degree Celcius. The constant pressure milar heat capacity of SiC varies with temperature as Cp= 50.79 + 1.97*10^-3T -4.92*10^6T^-2 + 8.20*10^8T^-3 J/mole.K.