CME 304 Definitions Recitation

quiz 9/10

Energy

• ability to do work

• a characteristic of a finite material body in equilibrium with its surroundings that gives it the capacity to convey some portion of this characteristic via thermal (heat) and/or mechanical (work) means to its immediate surroundings (or vice versa)

Heat

thermal energy

can be transferred to the system by surroundings or by the system to surroundings

Work

mechanical energy

transmission of energy by force

can be done by the system on the surroundings or by the surroundings on the system

System

the body of matter which you are studying

Subsystem

dividing the system (more systems within)

sub-parts separated by a sub-system boundary

each subsystem is treated as a separate entity

Surroundings

what is immediately outside of the system and capable of interacting with the system

System Boundary

where system and surroundings interact, separates them

may or may not allow the system to interact with its surroundings

Universe

totality of what you are studying

= system + surroundings

Phase

how the atoms are interacting

Thermodynamic Property

pressure, temperature, volume

Absolute Property

property that does not depend on a reference point

ex: density, heat capacity, thermal expansion, compressibility, electrical conductivity

Floating Property

property that requires a reference point to define, must be calculated based on reference conditions

ex: internal energy, enthalpy, entropy, Gidds Free Energy, Gravitational potential energy, Chemical potential, kinetic energy

DEPENDENT

Intensive Property

does not depend on size of the system

can vary from place to place within the system at any moment in time

ex: pressure, temperature, heat capacity, density, etc.

INDEPENDENT

Extensive Property

depends on the size of the system

can change with time as a system interacts with its surroundings

Non-property

does not depend on state of the system; depends on the process

Thermodynamic State

thermodynamic properties in a moment in time (reference point)

the sum totality of all its properties

Control Property

something that is fixed, can be externally prescibed to alter the energy state of a materials system

ex: pressure, temperature, volume, chemical composition

Dependent Property

response to something being done in the system

determined by the setting of controllable properties

ex: internal energy, enthalpy, entropy, free energy

Macrostate

bulk, outright measurement (not focusing on single atoms)

can be easily measured using laboratory equipment (i.e. P, T, V)

Microstate

atomic level states

thermodynamic properties are determined by microscopic quantum mechanical parameters

Macroscopic System

larger system (in reference to microscopic system)

system that is treated as a whole unit

Microscopic System

smaller system (in reference to macroscopic system)

a system treated as a collection of minute atomic/molecular discrete entities

Equation of State (EoS)

relating your thermodynamic properties (PV = nRT, PV = ZnRT)

if you are given two properties, this can be used to determine the third

Open system

system can flow into surroundings, lets mass/matter AND energy in

Closed system

boundary does not let mass/matter in, but DOES let energy in

Isolated system

boundary does not let mass OR energy in

think: thermos bottle

equilibrium

balance between rate of forward and rate of reverse reaction

mechanical equilibrium

mechanical energy is at equilibirum

no unbalanced forces acting on the system

system is stationary in time and space

chemical equilibrium

rate of forward = rate reverse

no chemical reactions take place at measureable rates

phase equilibrium

two phases existing simultaneously at a given P and T

path

connects one state to another (can vary in the way it gets there)

a specific pre-selected process whereby a system changes its proeprties acording to a prescribed set of parameters that describe the path

constraint

limiting the path/process

thermodynamic property is fixed at a pre-selected value and the thermodynamic process is carried out with this fixed value throughout

(i.e. constant temp, constant pressure, constant volume, etc.)

infinitesimal process

each step in the process is infinitely/unmeasureably small

finite process

measurable steps, finite changes in thermodynamic coordinates can be measured

quasi-static process

perform really slowly to maintain equilibrium

a process carried out so slowly that the system is always close to thermal, mechanical, or chemical equilibrium

isothermal

process carried out such that the temperature of system remains constant

adiabatic

process carried out such that heat does not enter/leave the system

isobaric

process carried out such that the pressure of system remains constant

isometric

process carried out where volume of system remains constant

reversible

process where you can return to your original state, idealized processes that do not occur in nature

irreversible

process where you cannot return to original state

system or surroundings (or both) are permanently changed

thermal equilibrium

heat transfer is 0

no temperature gradients throughout system

system must be at uniform temperature

no net heat flow between different systems