Module 1 -3 Terms & Definitions

closed system

(definition); (characteristics) mass cannot leave nor enter the system HOWEVER energy transfer can still occur

open system

(characteristics) mass/energy can leave and enter the system

1st law of thermodynamics

(definition) ΔU + ΔEk + ΔEp ± Q ± W = 0 (my assume K and P negligible depending on problem)
(how/when to use)

state function

a function that only depends on the current state of the system, the history or path to get there is negligible; enthalpoy, internal energy are state functions

enthalpy

(w/ state variables) H = U + PV;

what does phase rule indicate and what do we use it for?

F = 2 - pi + N
F = # of independent variables that must be fixed to establish intensive state of the system; degrees of freedom

N = # of components

internal energy

ΔU; energy of the molecules making the substance that are in ceaseless motion and have kinetic energy of translation, rotation, and kinetic energy - you do not know absolute value, ONLY changes

internal energy dependent on temperature AND molecular makeup/interactions present (INC of U, INC of temperature)

Cp

Cv

what is ideal gas law?

how to use ideal gas law?

what is van der Waals law?

(w/ variables)

what do variables in van der Waals indicate?

saturated vapor

boiling point of saturated liquid; mixture of sat. vapor and sat. liquid, in the midst of phase change so not yet complete → once tempoerature increases (is at boiling point) it means it is no longer in phase change and it is still considered saturated vapor; pressure constant

compressed/subcooled liquid

high pressure on liquid phase matter that is not ready to vaporize (essentially change phases); pressure constant

saturated liquid

pressure rises, temperature unchages from compressed liquid; in the midst of phase change so getting ready to vaporize as it is liquid at its boiling point; pressure constant

superheated vapor

at final temperature vapor is no longer saturated; pressure constant

can you draw P-V property diagram with sat. liquid, sat. vapor, critical point, etc.?

compressibility equation factor equation of state (w/ z)

distinguish between equilibrium and steady state

equilibrium is where there are no driving forces to change the parameters of a system whereas steady state is process where the parameters are kept constant with respect to time

adiabatic

no heat leaves or enters the system; an open OR closed system can be adiabatic and a system insulated well enough can be considered adiabatic; it is still possible for work can be added or removed even if it isn’t converted to heat like in the rankine cycle

isolated system

both closed AND adiabatic and cannot contribute to energy of surroundings in anyway as it is described as being very well insulated, so has neither energy OR matter entering or leaving the system

isochoric system

a system with constant volume, the matter itself doesn’t necessarily have t have constant volume as contents within the system however

isothermal system

constant temperature throughout the system ideally; realistically there is very little difference in points of temperature in different areas of the system; isothermal system is constant temperature with respect to position

isobaric system

constant pressure throughout the system ideally; isobaric process is constant pressure with respect to time

driving forces

thermal driving force: heat transfer between two objects due to difference in temperature and heat flowing where there is the absence of heat; where temp. is not at equilibrium as it is not at uniform temperature

mechanical driving force: ; ex) when velocity and height are changing as a function of time and the object cannot meet mechanical equilibrium as the force of gravity is greater than the upward air resistance force

chemical driving force: a prompt for a reaction to occur like b/w hydrogen and nitrogen to achieve a more stable phase