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Property

a macroscopic characteristic of a system that is independent of path (or process)

Intensive properties

pressure, temperature, density

State

the condition of a system as described by its properties

Process

the path of succession of states through which the system passes; more simply, the path of transformation from one state to another.

Steady state

the state for which the system's properties do not change with TIME

Thermodynamic cycles

a sequence of processes that begins and ends at the same state

phase

_______ is the degree portion of a cycle at any given time

Pure substance

element (atoms) or compound (molecules)

Thermodynamic equilibrium state

the state for which the properties do not have a tendency to change, in time and space, as long as the external conditions remain

Quasi-equilibrium state

the state for which the deviation from thermodynamic equilibrium is infinitesimal

Quasi-equilibrium process

the path of the succession of quasi-equilibrium states; an idealized process valid for many practical problems

E=KE+PE+U

Energy of a system

Internal energy, U

due to translational, rotational, vibrational motions, chemical bonds of molecules, and other like chemical energy in a battery

Work, W

A form of energy transfer of which the sole effect "could have been" the raising of a weight

Path function

A function that depends, not only on the properties of the two end states, but also on the path of the process; ex. W

Point function

A function that depends only on the properties of the two end states; ex. W of a polytropic process

Heat Transfer neglect criteria

good insulator, temp diff is small, surface area is too small to allow significant transfer, not enough time

Simple Compressible Substance

a substance whose magnetic and electrical effects are insignificant but changes in volume are very important

Simple compressible system

a system consisting of a simple compressible substance

State principal

the state of a simple compressible system at equilibrium can be uniquely determined by two independent intensive thermodynamic properties

Single-phase regions

solid, liquid, vapor

Two-phase regions

liquid-vapor, solid-liquid, solid-vapor

Triple line

the line along which three phases can exist in equilibrium

Saturation temperature

the temperature at which a phase change takes place at a given pressure

Saturation pressure

the pressure at which a phase change takes place at a given temperature

Subcooled liquid

the liquid of which temperature is lower than the saturation temperature; also called compressed liquid (pressure is higher than the saturation pressure)

Saturated liquid

a substance that exists as liquid at the saturation condition

Quality, x

the ratio of the mass of vapor present to the total mass of the liquid-vapor mixture; intensive property

Saturated vapor

a substance that exists as a vapor at the saturation condition

Dry saturated vapor

x=1; saturated vapor with no liquid, still in liquid-vapor dome; vf<=v<=vg

Superheated vapor

a vapor of which temperature is higher than the saturation temperature; substances called gases are generally highly superheated vapors

Vaporization and Condensation Conditions

can only occur when the pressure is lower than the critical pressure

Compressibility factor, Z

ratio of the product of the pressure and specific volume to the product of the gas constant and the temperature

Reduced pressure and temperature

ratio of the pressure/temperature to the critical pressure/temperature

Ideal Gas criteria

T>= 2*Tc && p<=.5*pc

pv=RT, pV=mRT, p=(density)RT

Ideal gas state eqn

Internal energy and enthalpy (I.G.M.)

thermally perfect; dependent ONLY on temperature

Calorically perfect

cp and cv are constant

Isobaric process

pressure is constant

Isometric process

volume is constant; also isovolumetric or isochoric

Reynolds Transport Theorem

coverts a closed system analysis into a control volume analysis and relates the time derivative of a system property to the rate of change of that property within a control volume at the instant …

Mass flow rate

mass flow through a system over time

Conservation of mass

the time rate of change of the mass in a control volume is equal to the sum of the mass flow rates at inlets minus the sum of the mass flow rates at exits

Mass flux

mass flow through an area

Volume flow rate

time rate of change of the volume

One-dimensional flow

flow that satisfies m(dot)=(density)(velocity)(area)

energy conservation

A principle stating that the total energy of an isolated system remains constant regardless of changes within the system.

Thermal reservoir

a body of a system of which temperature remains constant even when heat is added or removed

Clausius statement

it is impossible to construct a system that yields heat transfer from a cooler body to a hotter body without an input of work

Kelvin-Plank statement

it is impossible to construct a device that operates in a cycle, receives heat energy, and does work equal to or greater than the amount of heat energy received

Sources of irreversibilities

friction, heat transfer through a finite temperature difference, unrestrained expansion, mixing of substance at difference compositions or states, chemical reaction, electric current flow

Internal irreversibilities

irreversibilities within a system

External irreversibilities

irreversibilities outside the system (within the surroundings)

Internally reversible process

a process in which there are no internal irreversibilities

Thermal efficiency

ratio of energy sought to the energy cost; eta is independent of substance and relies only on Qh and Qc

Carnot corollaries 1

eta for a reversible cycle will always be greater than eta for an irreversible cycle when each cycle operates between the same two thermal reservoir

Carnot corollaries 2

eta's of all the reversible cycles are the same if they operate between the same two thermal reservoirs

Isentropic process

Reversible and adiabatic

Graph of Pressure against 1/Volume? Conditions?

Fixed temperature and amount of gas.

A constant.

What does pV equal for a fixed temperature and amount of gas?

Constant pressure.

Graph of temperature against Volume? Conditions?

A constant.

What does V/T equal at constant pressure?

p V = n R T

State the ideal gas law and units?

The gas constant.

What is R and what is its value?

How to convert bar to N m⁻² to Pa

1 bar = 1 x 10⁵ N m⁻² = 1 x 10⁵ Pa

XA = nA/n

How to work out the molar fraction, XA (XB etx) for a mixture?

What assumptions are made when using the ideal gas law?

The molecules have no volume (the volume of the molecules is negligible compared to the volume of the container)

1

What value does Z take for ideal gases?

When do deviations typically occur?

The volume of gases.

London dispersion forces - most molecules -

What types of intermolecular forces are there? What type of molecule do they occur between? What are their typical energy?

What are their units?

a depends upon the strength of interactions between molecules.