Thermodynamics Flashcards
Work in a Fluid System
Work in Expansion
W = ( - )
V2 > V1
dV = (+)
Work in a Fluid System
Work in Compression
W = ( + )
V1 > V2
dV = (-)
Work in a Fluid System
Work in Compression
Work is done on the system
Endergonic
+W
Work is done by the system
Exergonic
-W
Heat is absorbed by the system
Endothermic
+Q
Heat is released from the system
Exothermic
-Q
First Law of Thermodynamics
“Energy can neither be created not destroyed. It can only be converted from one form to another”.
ΔU = Q + W
Who wrote the First Law of Thermodynamics?
Rudolf Julius Emmanuel Clausius
It was introduced by Julius Robert Mayer and later on, James Prescott Joule
Second Law of Thermodynamics
“Heat never flows from a colder body to a hotter body, except when external energy is applied”.
For a spontaneous process, the entropy of the universe increases.
ΔS = Q/T
Who made the second law of thermodynamics?
Rudolf Clausius and William Thomson
It is based on Clausius statement of second law of thermodynamics
Refrigeration
It is based on Kelvin Planck’s statement of second law of thermodynamics.
Heat Engine
Third Law of Thermodynamics
“the entropy of a system approaches a constant value as the temperature approaches absolute zero”.
A perfect crystal at zero Kelvin has zero entropy.
S = kB log W
Who developed the third law of thermodynamics?
Walther Nernst
Non-spontaneous
Entropy
ΔS,univ < 0
Reversible, equilibrium
Entropy
ΔS,univ = 0
Spontaneous
Entropy
ΔS,univ > 0
Who is known as the father of thermodynamics?
Sadi Carnot
What is the formula for calculating the change in entropy of a system?
ΔS = Q/T, where ΔS is the change in entropy, Q is the heat transferred, and T is the absolute temperature.
Who proposed the concept of thermodynamic equilibrium?
Ludwig Boltzmann
What is the name of the law that states the internal energy of a system is a function of its state?
The first law of thermodynamics
What is the name of the law that states the pressure and temperature of a gas are directly proportional when volume is constant?
Gay-Lussac’s law
What is the name of the law that states the pressure and volume of a gas are inversely proportional when temperature is constant?
Boyle’s law
What is the name of the law that states the volume and temperature of a gas are directly proportional when pressure is constant?
Charles’s law
Who proposed the concept of heat engines
Nicolas Léonard Sadi Carnot
What is the name of the process by which a gas changes phase directly into a solid without passing through the liquid phase?
Direct solidification
What is the name of the law that states the work done by a system is equal to the change in its internal energy?
The first law of thermodynamics.
What is the name of the law that states the work done by a system is equal to the change in its internal energy?
The first law of thermodynamics.
What is the name of the law that states the entropy of an isolated system always increases over time?
The second law of thermodynamics.
What is the name of the law that states the internal energy of a system is a state function?
The first law of thermodynamics.
What is the name of the law that states the total energy of a closed system is constant?
The law of conservation of energy.
What is the name of the law that states the total energy of a closed system is constant?
The law of conservation of energy.
What is the name of the process by which a gas changes phase into a plasma?
Ionization
What is the name of the process by which a plasma changes phase directly into a gas without passing through the liquid phase?
Deionization
What is the name of the theoretical lowest possible temperature?
Absolute Zero
What is the formula for calculating the efficiency of a heat engine?
Efficiency = (W/QH) x 100%, where W is the work done by the engine and QH is the heat transferred to the engine from the hot reservoir.
What is the name of the law that states the entropy of a perfect crystal at absolute zero is zero?
The third law of thermodynamics
What is the name of the law that states the heat capacity of a substance is proportional to its mass?
The specific heat capacity.
What is the name of the law that states the heat transfer between two objects is proportional to the temperature difference between them?
Fourier’s law.
What is the name of the process by which heat flows from a hotter object to a cooler object?
Heat Transfer
What is the name of the law that states the internal energy of a system is equal to the sum of its kinetic energy and potential energy?
The law of equipartition of energy.
What is the name of the law that states the efficiency of a reversible heat engine is given by the ratio of the absolute temperatures of the hot and cold reservoirs?
Carnot’s theorem.
What is the name of the law that states the efficiency of a reversible heat engine is given by the ratio of the absolute temperatures of the hot and cold reservoirs?
Carnot’s theorem.
Van Der Waal’s Equation
(P + a(n/V)^2) (V - nb)= nRT
Pressure adjusts for the attractions and volumes of a gas
Specific Heat of Ideal Gases
Monoatomic Gases
Cp=5/2•R Cv= 3/2•R
Diatomic Gases
Cp=7/2•R Cv= 5/2•R
Mono, Di. Five and seven.
Which heat’s which,
now it’s heaven.
Cp>Cv: Countless Pizza > Cold Vodka (temperature)
Which law is the basis for the manufacture of thermometers?
Zeroth Law of Thermodynamics
Instances where work is zero
- No work in nozzle, it changed diameter only.
- straight pipes
Instances where Heat, Q is zero.
- Insulated nozzle, etc. (No heat losses)
- Adiabatic
Carnot Cycle
- Isothermal expansion: ΔS = Qʜ/Tʜ, where Q is the heat absorbed by the system from the high-temperature reservoir at temperature T1.
- Adiabatic expansion: ΔS = 0, since the process is reversible and adiabatic, so there is no heat exchange with the surroundings.
- Isothermal compression: ΔS = -Qc/Tc, where Q is the heat released by the system to the low-temperature reservoir at temperature T2.
- Adiabatic compression: ΔS = 0, for the same reason as in the adiabatic expansion.
Entropy
Non-flow means
Closed System
Entropy
Steady flow means
Open system
∆KE & ∆PE = 0
∆H =± Q ± W
Heat Effects
Difference of heat of combustion at P=K and V=k
∆H = ∆U = RT•∆ng
Heat Effects
Clapeyron Equation
E4-13
∆V = 1/p,liqd - 1/p,solid
Heat Effects
Clausius - Clapeyron Equation
E2-30
Normal Freezing Point Data
T = 0°C
p = 1 atm
∆Hf = 80 cal/g
Normal Boiling Point Data
T = 100°C
P = 1 atm
∆Hv = 540 cal/g
Quality
M = x(Msv) + (1-x)(MsL)
Assumption in Turbine
Adiabatic
∆S = 0
Adiabatic Pump
Foot note
W, isentropic = V∆P E4-51
∆H =Cp∆T + V(1-βT)∆P
∆S = Cp•ln(T2/T1) - βV∆P
Note that W for isentropic is V=k and W normal is P=k
Otto Cycle
- Isentropic compression: The entropy change for an isentropic process is zero (ΔS = 0) since it is a reversible adiabatic process.
- Isochoric Heating/Constant volume heat addition: The entropy change for a constant volume process can be determined using the equation ΔS = Qʜ/Tʜ, where Q is the heat added to the system and T is the temperature at which the heat is added.
- Isentropic expansion: Similar to the isentropic compression, the entropy change for this process is zero (ΔS = 0).
- Isochoric Cooling/Constant volume heat rejection: Again, the entropy change for a constant volume process can be determined using ΔS = Qc/Tc, where Q is the heat rejected by the system and T is the temperature at which the heat is rejected.
Diesel Cycle
- Isentropic compression: The entropy change for an isentropic process is zero (ΔS = 0) since it is a reversible adiabatic process.
- Isobaric Heating/Constant pressure heat addition: The entropy change for a constant pressure process can be determined using the equation ΔS = Qʜ/Tʜ, where Q is the heat added to the system and T is the temperature at which the heat is added.
- Isentropic expansion: Similar to the isentropic compression, the entropy change for this process is zero (ΔS = 0).
- Isochoric Cooling/Constant volume heat rejection: The entropy change for a constant volume process can be determined using ΔS = Qc/Tc, where Q is the heat rejected by the system and T is the temperature at which the heat is rejected.
