EYeeAAmdrMkwci10tKQf2Qaefb7ed7138a4e778902d8f08935d10bWORKSHEET13-THERMODYNAMICS

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School

The Shri Ram School, Gurgaon**We aren't endorsed by this school

Course

CHEM 123

Subject

Mechanical Engineering

Date

Jan 12, 2025

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Uploaded by AmbassadorOxide11581

WORKSHEET 13CH 10-Thermodynamics [26 marks]1. The pVdiagram shows a heat engine cycle consisting of adiabatic, isothermal and isovolumetric parts. The working substance of the engine is an ideal gas.The following data are available:pA= 5.00 × 105PaVA= 2.00 × 10−3m3TA= 602 KpB= 3.00 × 104PapC= 4.60 × 103Pa(a) Suggest why AC is the adiabatic part of the cycle.[2](b) Show that the volume at C is 3.33 × 10−2m3.[2](c) Suggest, for the change A B, whether the entropy of the gas is increasing, decreasing or ⇒constant.[2](d) Calculate the thermal energy (heat) taken out of the gas from B to C.[2]

(e) The highest and lowest temperatures of the gas during the cycle are 602 K and 92 K.The efficiency of this engine is about 0.6. Outline how these data are consistent with the second law of thermodynamics.[2]2. A frictionless piston traps a fixed mass of an ideal gas. The gas undergoes three thermodynamic processes in a cycle.The initial conditions of the gas at A are: volume = 0.330 m3 pressure = 129 kPatemperature = 27.0 °C

Process AB is an isothermal change, as shown on the pressure volume (pV) diagram, in which the gas expands to three times its initial volume.(a) Calculate the pressure of the gas at B.[2]The gas now undergoes adiabatic compression BC until it returns to the initial volume. To complete the cycle, the gas returns to A via the isovolumetric process CA.(b) Sketch, on the pVdiagram, the remaining two processes BC and CA that the gas undergoes.[2](c) Show that the temperature of the gas at C is approximately 350 °C.[2](d) Explain why the change of entropy for the gas during the process BC is equal to zero.[1](e) Explain why the work done by the gas during the isothermal expansion AB is less than the work done on the gas during the adiabatic compression BC.[1](f) The quantity of trapped gas is 53.2 mol. Calculate the thermal energy removed from the gas during process CA.[2]3. The diagram represents an ideal, monatomic gas that first undergoes a compression, then an increase in pressure.(a(i)) Calculate the work done during the compression.[1](a(ii)) Calculate the work done during the increase in pressure.

[1]An adiabatic process then increases the volume of the gas to 5.0×10−2m3.(b(i)) Calculate the pressure following this process.[2](b(ii)) Outline how an approximate adiabatic change can be achieved.[2]