![]() ![]() ![]() So, there is no change in volume and hence work-done in such process is zero. In this process, the working substance is kept in a nonexpanding chamber. Gas heated in a tightly sealed container. ![]() If dQ is the amount of heat given to the system, then it is partly used in increasing the temperature of the system by 'dT', and it is also partly used in doing external work 'dW' Now, from first law of thermodynamics, dQ = dU + dW or, dQ = nC v dT + PdVįurther, for isobaric process: P is constant, then the gas expands from volume V 1 to V 2 so work done in the process becomes dW = P or, dW = nR ( T 2 - T 1 ) ∴ dQ = dU + nR( T 2 - T 1 ) Isochoric Process: (Constant Volume) Any thermodynamic process, in which pressure and temperature of the system of gas changes, but its volume remains constant is called isochoric process. dT Using the value of dU from the equation (iii) in equation (ii), we gu nC v dT + PdV = 0 … (iv) For 'n' moles of ideal gas, the perfect gas equation is PV = nRT Differentiating both side with respect to T, we get d ( PV ) (ii) Also, if C v is the molar specific heat capacity of the gas at constant volume, then heat required to raise temperature through dT for n moles of gas is nC n dT. So, dQ = 0 Thus the equation (i) becoms 0 = dU + PdV ie, dU + PdV = 0. In adiabatic prucess, there is no exchange of heat. From first law thermodynamics, dQ = dU + PdV … (i). Now considering gas which undergoes expansion so that its pressure, volume and temperature change dP, dV and dT. Consider the gas have pressure P, volume V and temperature T at its initial state. Here, the locus AB of two isotherms shows there is change id temperature without external supply of heat and represents the adiabatic expansion of gas.Īdiabatic equation of a perfect gas Ler's consider 'n' moles of ideal gas inside a cylinder with nonconducting wall and frictionless piston. Slow compression of air in the tyre using pump Equation of state in Isothermal process From Ideal gas equation, we have PV = nRT ……………….(i) Here For isotherma process, T = constant the equation (i) becomes PV = Constant The melting and boiling process of substance at constant temperature. If a system is in contact with a thermal reservoir from outside, then, to maintain thermal equilibrium, the system slowly adjusts itself with the temperature of the reservoir through heat exchange. Usually, there are two phenomena under which this process can take place. At a particular constant temperature, the change of a substance, object or system is known as Isothermal Process. The transfer of heat into or out of the system happens so slowly that thermal equilibrium is maintained. State Variables specifically refer to the change inherent if a reaction proceeds because of a change in state State variables are either extensive or intrinsic Extensive → variables which are proportional to the quantity of matter (such as volume) Intrinsic → variables which are independent of quantity, that instead describe the whole system (such as density, temperature, and concentration) Thermodynamic System (Process) Isothermal Process Iso => constant, thermal=> temperature A thermodynamic process in which pressure and volume of system of a gas change but temperature remains constant is called isothermal process.The state is defined by specifying certain variables such as temperature, pressure, volume and composition. ![]()
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