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21 Cards in this Set
- Front
- Back
Macroscopic |
-system is analyzed with reference to its molecular structure or molecular behaviour |
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Microscopic |
-system is analyzed with reference to its molecular structure or molecular behaviour |
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Microscopic vs Macroscopic |
Large number of variables | LessTime consuming calculations | faster and simpleStatistical thermodynaics by pure scientist | applied thermodynamics by engineers |
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Closed System |
System in which energy transfer can take place but mass cannot.. Eg : Ideal gas contained in a piston cylinder. Total mass of closed system is always constant. so called Control Mass |
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Open System |
System in which both mass and energy can take place. eg : air compresser, also called controlled volume |
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Isolated System |
system in which neither mass nor energy can take place. Eg : Closed Rigid isolated box |
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Thermodynamic property |
Any variable or parameter used to describe thermodynaic system. divided into intensive and extensive properties |
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Intensive property |
Thermodynamic property which is independent of mass or part of system considered. Eg. pressure, temperature |
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Extensive property |
Thermodynamic property which is dependent upon the mass or part of the system. Eg : entropy, enthalpy, volume. |
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Extensive to Intensive |
Since extensive properties are proportional to mass, they can be converted into intensive by dividing them by mass.e = E/me = Specific energy (usually denoted by small letters)E = Total Energy(usually denoted by capital letters)m = Mass |
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Thermodynamic Equilibrium |
If there is no change in any properties of the system when it is isolated from its surroundings.If all intensive properties have same value throughout the systemIf there is no change in any properties of the system when it is isolated from its surroundings.If all intensive properties have same value throughout the system |
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Condition for thermodynamic system to be in equilibrium |
Thermal equilibrium, chemical equilibrium, mechanical equilibrium: Thermal equilibrium : There should be no temperature difference within the system Chemical equilibrium : There should be no chemical reaction during observation interval Mechanical equiliubrium : There shouldn't be any pressure difference or unbalanced force/moment within the system. |
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Thermodynamic state |
Each unique condition at which a thermodynamic system can exist is thermodynamic state. It is specified with the values of thermodynamic properties. eg : State 1 at T1 = 25 C P1=1 Pa , State 2 at T2=50 P2 = 2Pa Constant property and Variable property |
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State functions |
All thermodynamics properties depend only on the end states and they are called state functions. |
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Path functions |
Variables such as work and heat depend not only on the end states but also on the path and are called path fuctions. |
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Thermodynamic process |
The path followed by system when it undergoes from one equilibrium state to another is called thermodynamic process. Thermodynamic process is defined with the help of property diagrams such as P-V, T-V, P-T, h-s, T-s , P-h diagrams etc. |
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Reversible process |
Any process which passes through a series of equilibrium states such that each intermediate state can be located on a property diagram is called reversible process. |
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Irreversible process |
Any process which passes through a series of intermediate states which can not be defined or cannot be located on property diagram is called an irreversible process. Represented by broken line |
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Reversible/Irreversible Example |
Take two piston-cylinder device, one with a huge block and other with number of small blocks. Removing from first block one by one and adding again is reversible process but adding big block and removing is not reversible process. |
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Pressure |
Pressure exerted by ambient air on any surface is called atmospheric pressure.
Pressure of any system measured with reference to atmospheric pressure is called gauge pressure.
Pressure of system expressed relative to perfect vacuum is called absolute pressure.
Pabs = Patm + Pgauge |
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Zeroth law of thermodynamics |
Consider three systems A,B and C. A-C contact same temperature, B-C contact same temperaturem then A-B will be same temperatue without testing. |