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Thermodynamic Terms: System: Surroundings: Boundary: Types of Systems Open System: Closed System: Isolated System

The document provides an overview of thermodynamic concepts including systems, processes, laws, and key formulas. It describes types of systems (open, closed, isolated), thermodynamic processes (isothermal, adiabatic, isochoric, isobaric), and the laws governing thermodynamics such as the First and Second Laws. Additionally, it covers heat engines, efficiency, the Carnot engine, and the concept of entropy.

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12 views3 pages

Thermodynamic Terms: System: Surroundings: Boundary: Types of Systems Open System: Closed System: Isolated System

The document provides an overview of thermodynamic concepts including systems, processes, laws, and key formulas. It describes types of systems (open, closed, isolated), thermodynamic processes (isothermal, adiabatic, isochoric, isobaric), and the laws governing thermodynamics such as the First and Second Laws. Additionally, it covers heat engines, efficiency, the Carnot engine, and the concept of entropy.

Uploaded by

dhruvanrashmi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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1.

Thermodynamic Terms

 System: The part of the universe under observation.


 Surroundings: Everything external to the system.
 Boundary: The real or imaginary surface separating the system and its surroundings.

Types of Systems

 Open system: Exchanges both matter and energy (e.g., boiling water in an open pot).
 Closed system: Exchanges only energy, not matter (e.g., a closed gas cylinder).
 Isolated system: No exchange of matter or energy (e.g., thermos flask).

2. Thermodynamic Processes

 Isothermal Process: Constant temperature (ΔT=0\Delta T = 0ΔT=0)


o Example: Melting of ice.
o PV=constantPV = \text{constant}PV=constant
 Adiabatic Process: No heat exchange (Q=0Q = 0Q=0)
o Example: Rapid compression of gas.
o PVγ=constantPV^\gamma = \text{constant}PVγ=constant
 Isochoric Process: Constant volume (ΔV=0\Delta V = 0ΔV=0)
o Example: Heating gas in a sealed rigid container.
 Isobaric Process: Constant pressure (ΔP=0\Delta P = 0ΔP=0)
o Example: Boiling water at atmospheric pressure.

3. Zeroth Law of Thermodynamics

 If two systems are individually in thermal equilibrium with a third system, they are
also in thermal equilibrium with each other.

4. First Law of Thermodynamics (Law of Energy Conservation)

 Statement:
The change in internal energy (ΔU\Delta UΔU) of a system is equal to the heat
supplied to the system (QQQ) minus the work done by the system (WWW).
ΔU=Q−W\Delta U = Q - W ΔU=Q−W
 Special Cases:
o Isothermal Process: ΔU=0\Delta U = 0ΔU=0, so Q=WQ = WQ=W
o Adiabatic Process: Q=0Q = 0Q=0, so ΔU=−W\Delta U = -WΔU=−W
o Isochoric Process: W=0W = 0W=0, so ΔU=Q\Delta U = QΔU=Q
o Isobaric Process: Q=ΔU+WQ = \Delta U + WQ=ΔU+W
5. Second Law of Thermodynamics

 Heat cannot spontaneously flow from a colder body to a hotter body.


 Kelvin-Planck Statement:
It is impossible to construct a device that operates in a cycle and converts all heat into
work.
 Clausius Statement:
Heat cannot flow from a colder body to a hotter body without external work.

6. Heat Engines and Efficiency

 Heat Engine: A device that converts heat energy into mechanical work.
o Q1Q_1Q1 = Heat absorbed from the source
o Q2Q_2Q2 = Heat rejected to the sink
o Efficiency (η\etaη): η=WQ1=Q1−Q2Q1\eta = \frac{W}{Q_1} = \frac{Q_1 -
Q_2}{Q_1} η=Q1W=Q1Q1−Q2

7. Carnot Engine

 An ideal reversible heat engine operating between two temperatures T1T_1T1 and
T2T_2T2.
 Efficiency of Carnot Engine: η=1−T2T1\eta = 1 - \frac{T_2}{T_1} η=1−T1T2
Where T1T_1T1 = Temperature of the hot reservoir, T2T_2T2 = Temperature of the
cold reservoir.

8. Entropy (SSS)

 A measure of disorder or randomness in a system.


 Change in entropy (ΔS\Delta SΔS): ΔS=QT\Delta S = \frac{Q}{T} ΔS=TQ
 Entropy increases in irreversible processes and remains constant for reversible
processes.

Key Formulae to Remember

1. First Law: ΔU=Q−W\Delta U = Q - WΔU=Q−W


2. Work done in isothermal process: W=nRTln⁡V2V1W = nRT \ln \frac{V_2}
{V_1}W=nRTlnV1V2
3. Work done in adiabatic process: W=P1V1−P2V2γ−1W = \frac{P_1V_1 - P_2V_2}{\
gamma - 1}W=γ−1P1V1−P2V2
4. Efficiency of Carnot engine: η=1−T2T1\eta = 1 - \frac{T_2}{T_1}η=1−T1T2

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