Thermodynamics Flashcards by Margarita V

is a branch of physical science that deals with the study of interrelation of various
forms of energy.

Thermodynamics

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Work done ON the system

a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic

Endergonic

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Work done BY the system

a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic

Exergonic

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___________ 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

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is a thermodynamic process or reaction that releases energy from the system to its surroundings

a. Endergonic
b. Exergonic
c. Endothermoc
d. Exothermic

Exothermic

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Which law is the basis for the manufacture of thermometers

Zeroth Law of thermodynamics

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The credit for formulating the Zeroth law goes to _______

Ralph Howard Fowler

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Type of system that allows transfer of both matter and energy

Open System/Control Volume

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type of system that allows exchange of energy only

Closed System

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type of system that allows neither transfer of matter nor energy

Isolated System

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real/imaginary or fixed/moving surface that separates the system from its surroundings and where exchange of matter or energy takes place

Boundary

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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

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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

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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

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state that exists between two subsystems of equal
pressure (there is no unbalanced force/ pressure gradient on the system)

Mechanical Equilibrium

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state that exists between two subsystems of equal temperature

Thermal Equilibrium

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any change that undergoes within a system that causes shift from one equilibrium state to another

Process

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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

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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

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a thermodynamic process in which the net rate of heat transfer to and from the system is zero

Adiabatic/Isocaloric process

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Constant temperature process

Isothermal

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Constant pressure process

Isobaric

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Constant volume process

Isochoric/Isometric

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_______ functions that depend on the current state of the system and not on how the system reaches that state

State/point functions

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______ 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

1. Shaft 2. Spring 3. 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

1. Open Type 2. 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:

1. Heat 2. Work 3. 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

1. Power Cycle 2. Refrigeration Cycle 3. 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

1. Clausius Statement 2. 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

Thermodynamics Flashcards

(124 cards)