4. A closed gas cylinder assembly undergoes a process from state 1 to state 2. Assuming the process to be a polytropic process, is the process reversible? Why?- When a gas undergoes a reversible process in which there is heat transfer, the process frequently takes place in such a manner that a plot of the log P (pressure) vs log V (volume) is a straight line. This type of process is called a polytropic process and is defined as pVn = constant.5. How is enthalpy defined? Explain what each term in the equation means and state its units in S.I system.- Enthalpy is defined as astate functionthat depends only on the prevailing equilibrium state identified by the variables internal energy, pressure, and volume. Enthalpy is defined in the following equation:H = U + pVwhere H = the enthalpy of the system, in Joules or Nm U = the internal energy of the system, in Joules or Nm p = the pressure in the system, in Pascals or N/m2 V = the volume of the system, in m36. How are specific heats at constant pressure (cp) and constant volume (cv) defined in terms of enthalpy and internal energy?

- Specific heat at constant volume is the change of specific internal energy with respect to temperature when the volume is held constant (Isometric process) and is defined as:

- Specific heat at constant pressure is the change of specific enthalpy with respect to temperature when the pressure is held constant (Isobaric process) and is defined as:

7. What is an incompressible substance in Thermodynamics? Give some examples of incompressible substances. How are Cp and Cv related for incompressible substances? - An incompressible substance is a substance whose specific volume (or density) is constant. Solids and liquids are incompressible substances. The specific heats at constant pressure and constant volume for incompressible substances will reduce into one specific heat constant which is a function of temperature only:Cp= Cv= C8. What are the Cp and Cv values for Aluminum, Copper, Iron and Lead?The following table represents the values for Cp and Cv of Alumimum, Copper, Iron and LeadMaterialCp (kJ/kg K)Cp (kJ/kg K)

Aluminum0.91------

Copper0.39------

Iron0.45------

Lead0.13------

9. What specifications should an ideal gas follow? How are Cp and Cv related for ideal gas?- An ideal gas is a theoretical gas composed of a set of randomly-moving, non-interacting point particles. The ideal gas concept is useful because it obeys the ideal gas law, a simplified equation of state, and is amenable to analysis under statistical mechanics.Using the definition of enthalpy (h = u + Pv) and writing the differential of enthalpy, the relationship between the specific heats for ideal gases is

10. What are the CP and CV values for Air, CO2 and O2 at 350K, 600K and 900K? State the units of CP and CV. What is the value of the ratio of specific heats for Air, CO2 and O2 at 350K, 600K and 900K? Assume Air, CO2 and O2 to be ideal gases.- The following tables are the Cp, CV and k values for Air, CO2 and O2 at different temperatures:Air

Temperature KCp kJ/kg KCv kJ/kg Kk Cp/Cv

3501.0080.7251.4

6001.0510.7641.376

9001.1210.8341.344

CO2

Temperature KCp kJ/kg KCv kJ/kg Kk Cp/Cv

3500.8950.7061.268

6001.0750.8861.213

9001.2041.0151.186

O2

Temperature KCp kJ/kg KCv kJ/kg Kk Cp/Cv

3500.9280.66821.389

6001.0030.74321.350

9001.0740.81421.319

11. Is Internal Energy a point or a path function? Is work done a point or path function?Internal Energy is a state function, and the work done is a path function.

12. What assumptions are we making when we state E = U?We assume that the change in the overall energy, E, is equal to the change in the internal energy, U occurs when the values for the change in the kinetic energy KE and the change in the potential energy PE are negligible or equal to 0.