Isothermal Isobaric Isochoric Adiabatic Processes.pptx

Thermodynamics unit for BTEC

1. Thermodynamic Processes - Isothermal To keep the temperature constant both the pressure and volume change to compensate. (Volume goes up, pressure goes down) i.e. BOYLES’ LAW P V 2 1 Isotherm Isothermal T 1 = T 2 (Constant Temperature) V 1 V 2 T 1 = T 2 Q -W Net Work Done

2. Thermodynamic Processes - Isobaric Heat is added to the gas which increases the Internal Energy (U). Work is done by the gas as it changes in volume. The path of an isobaric process is a horizontal line called an isobar. 2 1 V 1 V 2 Isobar T 1 T 2 T 2 >T 1 Q -W Isobaric P 1 = P 2 (Constant Pressure) P V Net Work Done

3. Thermodynamic Processes – Isovolumetric (Isochoric) 2 1 V 1 = V 2 Isomet T 1 T 2 T 2 >T 1 P V Isovolumetric V 1 = V 2 (Constant Volume) Q W = 0

4. Thermodynamic Processes - Adiabatic ADIABATIC- GREEK (adiabatos- "impassable") In other words, NO HEAT can leave or enter the system, it is fully insulated. V 1 V 2 P V Adiabatic = Nothing is Constant T 1 T 2 T 1 >T 2 2 1 Adiabat Q = 0 -W

5. In Summary P V (b) (a) (c) (d) Label Process Important Points Gas Law a Isothermal Constant T, Δ U = Q , Q = W By Boyles Law b Isovolumetric (isochoric) Constant V, W = 0, Δ U = Q Charles Law c Isobaric Constant P, Δ U = Q - W By Pressure Law d Adiabatic Nothing is Constant, Q = 0, Δ U = - W By Combined Gas Law Isobaric Isothermal Isochoric Adiabatic