of gaseous state -isothermal, adiabatic, reversible, irreversible, and cyclic. (2) Calculate corresponding values if the above process is carried out reversibly. Work done by a constant force and a variable force kinetic energy, work. V constant, where g V G Work done in an adiabatic process is W nRT ( 1. (1) Calculate final temperature q, w, ΔH & ΔU work done by the system is equal to decrease. 2 moles of an ideal diatomic gas (C V = 5/2 R) at 300 K, 5 atm expanded irreversibly and adiabatically to a final pressure of 2 atm against a constant pressure of 1 atm. How much work is done on the gas ?Įxample 5. dW+dUdQ For adiabatic change dQ0 therefore dW-dU But dUCv dT therefore dW-Cv dT Cp-Cv R implies gamma Cv-CvR implies Cv(gamma-1) R implies Cv. 2 mole of a gas at 1 bar and 300 K are compressed at constant temperature by use of a constant pressure of 5 bar. In adiabatic processes, the work done by the system alters the internal energy of the system. For example, if we quickly press the piston in a cylinder filled with gas, there is not enough time for the system to transfer heat energy to the surroundings. From the given data find out whether the process is isochoric or not ? also calculate q, w, Δ U, Δ H,Įxample 4. An adiabatic process can be quickly maintained by doing the process. 4 moles of an ideal gas (C v = 15 J) is subjected to the following process represented on P - T graph. The pressure of liquid is a linear function of volume (P = a + bV) and the internal energy of the liquid is U = 34 + 3PV find a, b, w, ΔE & ΔH for change in state from 100 Pa, 3m 3 to 400 Pa, 6m 3Įxample 3. ![]() dUdQ-dW dQ0 by definition, Therefore, 0dQdU+dW The work done dW for the change in volume V by dV is given as PdV. 1150 Kcal heat is released when following reaction is carried out at constant volume.įind the heat change at constant pressure. The equation for an adiabatic process can be derived from the first law of thermodynamics relating to the change in internal energy dU to the work W done by the system and the heat dQ added to it. If temperature were maintained constant through out the change and system delivers 748.26 J of work, determine the final gas pressure and describe the process on PV diagram.Įxample 2. 2 moles of an ideal gas initially present in a piston fitted cylinder at 300 K, and 10 atm are allowed to expand against 1 atm but the piston was stopped before it stablished the mechanical equilibrium. P 1 = 1 atm, P 2 = 5 atm, P ext = 5 atmĮxample 1. A dilute gas expands quasi-statically to three times its initial volume. Show that the work done by the gas is given by W nR 1 (T 1 T 2). ![]() Workdone in 2 nd stage > Workdone in I st stage The temperature of n moles of an ideal gas changes from T 1 T 1 to T 2 T 2 in a quasi-static adiabatic transition. For reversible & irreversible isobaric or isochoric process, workdone is same.
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