Thermodynamics Flashcards
is a branch of physical science that deals with the study of interrelation of various
forms of energy.
Thermodynamics
Work done ON the system
a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic
Endergonic
Work done BY the system
a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic
Exergonic
___________ reactions are chemical reactions in which the reactants absorb heat energy from the surroundings to form products
a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic
Endothermic
is a thermodynamic process or reaction that releases energy from the system to its surroundings
a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic
Exothermic
Which law is the basis for the manufacture of thermometers
Zeroth Law of thermodynamics
The credit for formulating the Zeroth law goes to _______
Ralph Howard Fowler
Type of system that allows transfer of both matter and energy
Open System/Control Volume
type of system that allows exchange of energy only
Closed System
type of system that allows neither transfer of matter nor energy
Isolated System
real/imaginary or fixed/moving surface that separates the system from its surroundings and where exchange of matter or energy takes place
Boundary
a state in which (a) the properties of the system do not vary with time, (b) the system is uniform where there is no internal temperature, pressure, concentration or velocity gradient, (c) the net flows of heat, mass or work between the system and its surroundings are zero and (d) the net rate of all chemical reactions is zero
Equilibrium state
a thermally-insulating boundary in which no change of state is observed even though two objects at different temperatures are brought into contact (a boundary that does not let heat to transfer)
Adiabatic Boundary
a thermally-conducting boundary in which a change of state is observed when two objects of different temperatures are brought into
contact (a boundary that allows heat to transfer)
Diathermic Boundary
state that exists between two subsystems of equal
pressure (there is no unbalanced force/ pressure gradient on the system)
Mechanical Equilibrium
state that exists between two subsystems of equal temperature
Thermal Equilibrium
any change that undergoes within a system that causes shift from one equilibrium state to another
Process
a sufficiently slow process that allows the system to internally adjust so that the properties in one part does not change faster than the other parts
Quasi static/Quasi-equilibrium process
process where a fluid flows through a control volume and the fluid properties can change from point to point within the control volume, however at any fixed point these properties remain constant during the entire process
Steady flow process
a thermodynamic process in which the net rate of heat transfer to and from the system is zero
Adiabatic/Isocaloric process
Constant temperature process
Isothermal
Constant pressure process
Isobaric
Constant volume process
Isochoric/Isometric
_______ functions that depend on the current state of the system and not on how the system reaches that state
State/point functions
______ functions that depend on the path followed during a process
Path functions
form of energy transferred from one body to another by virtue of a temperature difference
Heat (Q)
form of energy that results in the motion of a body by virtue of an opposing force; energy transfer associated with a force acting through a distance
Work (W)
What are the THREE Mechanical forms of Work
- Shaft
- Spring
- Surface Tension
The DISORDERLY or RANDOM molecular motion for transfer of energy as heat is also called ______ motion of molecules
Thermal
When work is done BY the system, molecules move in a/an ________ way
organized/orderly
This refers to the energy of the system as a bulk which can be associated with the velocity and location of its center of mass
External Energy
It is the energy due to the translational motion of the system relative to some point of reference or to the rotation of the system about an axis
Kinetic Energy
It is the energy due to the position of the system in a potential field such as electromagnetic field or gravitational field
Potential Energy
“Energy of the universe is constant”
1st law of thermo
“Energy can neither be created nor destroyed but can only be changed from one form to another”
Law of Conservation of Energy
“If body A is in thermal equilibrium with body B, and the body B is in thermal equilibrium with body C, then body A is in thermal equilibrium with body C.”
Zeroth Law of thermo
principle of thermal equilibrium between thermodynamic systems in contact
Zeroth Law of Thermo
The first explicit statement of the 1st Law of Thermodynamics was given by _______
Rudolf Julius Emmanuel Clausius
refers to the total energy of the system in the molecular level which can be due to the motion of molecules relative to the center of mass of the system, or to the rotational and vibrational motion and the electromagnetic interactions of the molecules, or to the motion and interaction of the atomic and subatomic components of the molecules
Internal Energy (U)
energy associated with the kinetic energy of the molecules as it moves at a certain velocity through space
Translational KE
energy associated with the back-and-forth motion of the atoms in a polyatomic molecule about their common center of mass
Vibrational KE
energy associated with the rotation of the atoms in a polyatomic molecule about an axis
Rotational KE
energy associated with the rotation of the subatomic particles about their axes
Spin Energy
states that the total kinetic energy of a system is shared equally among its independent components once the system attains thermal equilibrium
Equipartition Theorem of energy
It is the measure of total energy of a thermodynamic system
Enthalpy
Describes the temperature change of a fluid when it is forced to flow through a valve or porous plug adiabatically
Joule-Thompson effect
Involves measurement of heat involved in a chemical reaction or physical change
Calorimetry
What are the TWO TYPES of Calorimeter
- Open Type
- Bomb Type
Type of Calorimeter that operates at constant pressure
Open Type
Type of Calorimeter that operates at constant volume
Bomb Type
A device that INCREASES the VELOCITY of the fluid resulting to a DECREASE in its PRESSURE
Nozzle
A device that DECREASES the VELOCITY of the fluid resulting to an INCREASE in its PRESSURE
Diffuser
Compressors, fans, and pumps are devices used to ____________ the pressure of a fluid by the supply of work through a rotating shaft.
a. Increase
b. Decrease
c. Both
d. Hatdog
a. Increase
________ are used to transport a gas by increasing its pressure slightly
a. Compressors
b. Fans
c. Pumps
d. None of the above
b. Fans
Compressors and pumps are devices capable of increasing the pressure of ___________.
a. Gases only
b. Liquids only
c. Both
d. Solids
c. Both
Refers to any flow-restricting device such as an adjustable valve, porous plug or a capillary tube
Throttling Valves
T or F
Throttling device operates at constant enthalpy
True
What is constant enthalpy
Isenthalpic
“All processes in nature tend to occur only with an increase in entropy and that the direction of change is always such as to lead to the increase in entropy”
2nd Law of Thermodynamics
This law states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.
Hess’ Law
The __________ process equation describes expansion and compression processes which include heat transfer.
Polytropic
He proposed the Carnot Cycle
Nicolas Leonard Sadi Carnot
type of system that consists of a fixed amount of mass while its volume does not have to be fixed
Closed System
Equation which relates pressure, volume, and temperature of a gas is called
a. Equation of state
b. Ideal gas eauation
c. Gibbs
d. All of these
a. Equation of state
The equation PV=nRT is best obeyed by gases at
a. low P, high T
b. high P, low T
c. both low
d. both high
a. low P, high T
low P > attractive and repulsive forces become negligible because molecules are spread out
high T > collisions are elastic so KE is preserved
Compressibility factor of a gas is
a. not a function of P
b. not a function of its nature
c. not a function of its T
d. unity, if it follows PV=nRT
d. Unity
Cp - Cv = R is valid for
a. gases at very high P
b. gases at very low T
c. ideal gases
d. all gases
c. Ideal gases
For monoatomic gases, Cp/Cv equals
1.67
For an isothermal process, the internal energy of a gas
a. Increases
b. Decreases
c. remains unchanged
d. data is insufficient
c. Remains unchanged
Cp/Cv for Diatomic is
1.4
In an adiabatic process
a. heat transfer is zero
b. temperature change is zero
c. work done is a path function
d. enthalpy remains constant
a. heat transfer is zero (Q=0)
From PV^n=C, when n=0, the process is
a. isochoric
b. isothermal
c. polytropic
d. isobaric
d. Isobaric
From PV^n=C, the process is isochoric if n equals
infinity
A solid is transformed into a vapor without gaoing through the liquid phase at
a. below triple point
b. boiling point
c. triple point
d. always
a. below triple pt
Work output of turbine is ______ the work input to the pump to have profit
a. less than
b. equal to
c. greater than
d. less than or greater than
c. greater than
- so that there will be excess energy that can be sold
The efficiency of Carnot cycle is ______ the efficiency of Rankine cycle
a. less than
b. greater than
c. equal to
d. less than or greater than
b. greater than
Any characteristic of a system is called a __________
Property
Properties that are independent of the mass of the system
Intensive Property
Properties that depend on the size or extent of the system
Extensive Property
Extensive property per unit mass is called _______
Specific property
Energy can be transferred to or from a system in THREE FORMS:
- Heat
- Work
- Mass
Cp for Water
4.187 KJ/kg•K
1.001 BTU/lbm•F
It is a substance that has a fixed chemical composition throughout
Pure substance
It is the attraction between molecules
Intermolecular bonds
Intermolecular bonds are strongest in ________ and weakest in gases
a. gases
b. liquids
c. solids
d. solids and liquids
c. solids
- because molecules in solids are closely packed together
Triple pt temp of water
0.01 C
4.58 mmHg
The amount of heat added to effect the phase change is equal to the change in ________
a. U
b. H
c. Q
d. All of the above
b. H, Enthalpy
It is the change of enthalpy between solid and liquid
Latent heat of fusion
It is the change of enthalpy between liquid and vapor
Latent heat of vaporization
It is the change of enthalpy between solid and vapor
Latent heat of sublimation
At a given pressure, the temperature at which pure substance changes phase is called _______ temperature
saturation
A ______ process would restoee the system to its INITIAL STATE
Reverse
_____________ are bodies that can exchange an infinit amount of heat with the system but their temperature never changes
Thermal Reservoir
What are the THREE types of Thermodynamic Cycles
- Power Cycle
- Refrigeration Cycle
- Heat Pump Cycle
Devices used to convert HEAT TO WORK (produces work from heat)
Heat Engine
Heat Engines operate on a _______ cycle
Power cycle
-because it produces Work
Thermal efficiency is always ______ than unity
less
Thermal efficiency of ordinary spark ignition engines
about 20%
Thermal efficiency of diesel engines and large turbine plants
about 30%
Thermal efficiency of large steam power plants
about 40%
Fluid which heat is transferred while undergoing a cycle
Working fluid
Working fluid used in the REFRIGERATION cycle
Refrigerant
Mostly used working fluid in Heat Engines
Water
Output for a Heat Engine
Work
Output of Refrigerators
Qc
- removes heat thus requires a work input
It is a reversed Heat Engine
Heat Pump
Refrigerators and _________ operate on the same cycle but different purpose
a. Heat pump
b. Heat Engine
Heat Pump
• Heat Pump - supplies heat to hot reservoir to maintain a heated space
• Refrigerator - removes heat from cold reservoir
COP of Heat Pump is always ________ than unity
greater
- because COP of Refrigerator is a positive quantity
Heat Pumps today have seasonally averaged COP of ______
2-3
“It is impossible to devise a cycle such that its only effect is the transfer of heat from a low temp body to a high temp body”
Clasius Statement
because a non spontaneous process needs work
“It is impossible to build a cycle engine that will have a thermal efficiency of 100%”
Kevin Planck
All work can be converted to heat but ALL HEAT CANNOT BE converted to work
T or F
A cycle that obeys 1st Law also obeys 2nd Law
False
What are the TWO Statements of SECOND LAW of Thermodynamics
- Clausius Statement
- Kevin Planck
It is a device that violates the laws of thermodynamics
Perpetual Motion Machine (PMM)
A cyclic process that has the highest efficiency
Carnot Cycle
When a Carnot cycle is reversed it becomes a ______________
Carnot Refrigeration Cycle or a Carnot Heat Pump Cycle
Quantitative measure of microscopic disorder for a system
Entropy
if S total < 0, is the process feasible?
not feasible
if S total > 0, is the process feasible?
feasible but irreversible
if S = 0, is the process reversible or irreversible?
reversible
losses in condenser are _______
small
large
always constant
none
small
Actual work delivered divided by the corresponding ideal work is known as _______ efficiency
turbine
Which of the following gives the most work we can get out of an adiabatic system
irreversible compression
irreversible expansion
reversible expansion
reversible compression
reversible expansion
what happens to delta U when work is done by the system during the adiabatic expansion of ideal gas
zero
decreases
no change
increases
decreases
