Term | Definition |
system | any element of space or matter specifically set aside for study |
surroundings | everything outside of the system |
system boudary | interface between the system and the surroundings (want to identify flows of energy into/out of system) |
isolated system | no mass, heat, work can cross the system boundary; does not interact with the surroundings in any way |
adiabatic | no heat transfer; no heat into or out of the system (perfectly insulated) |
1st law of thermodynamics | conservation of energy |
property | any quantity that describes the state of the system and whose value depends solely on the state of the system ( does NOT depend on the process) |
internal properties | define the state of the system
ex: temperature, pressure, internal energy, enthalpy, specific volume |
external properties | velocity and height |
intensive properties | properties that are independent of mass
ex: T, P, v, u, h, s |
extensive properties | properties that depend on mass
ex: U, H, V |
state principle | any 2 independent intensive thermo properties are sufficient to determine the equilibrium state of a pure, simple, compressible substance |
equilibrium | the state of the system is not changing at all (all properties are fixed in relation to each other) |
quasi-equilibrium | state is changing slowly (slow enough to be considered in equilibrium) |
dynamic equilibrium | stuff is happening but on average nothing is changing (gas may turn into liquid and liquid into gas but they occur at the same rate) |
intrinsic properties | a property that is independent of other things (including context/ surroundings) |
closed system | always contains the same matter; there is no transfer of mass (control mass) |
state | the condition of the system as described by its properties |
process | a transformation from one state to another |
steady state | when none of the properties change with time |
specific volume | reciprocal of density; the volume per unit mass |
absolute pressure | pressure with respect to the zero pressure of a complete vacuum |
power | rate of energy transfer by work |
thermodynamic cycle | a sequence of processes that begins and ends at the same state |
pure sustance | is uniform and invariable in chemical composition |
phase | quantity of matter that is homogeneous throughout in both chemical and physical structure |
saturation state | a state at which a phase change begins or ends |
critical point | where saturated liquid and saturated vapor lines meet |
vapor dome | dome-shaped region composed of 2 phase liquid-vapor states |
quality | the ratio of mass of vapor present to the total mass of the mixture |
enthalpy | H=U+pV |
perfect gas | ideal gas with constant specific heat |