Thermodynamics/Definitions


 * Equilibrium (plural = equilibria) : No change or tendency to change


 * Steady-State : No change with respect to time
 * There may however, be change with respect to position


 * System : Whatever we are interested in
 * For example: an engine, a reactor, or a living cell


 * Surroundings : Everything else outside of the system


 * Closed System : A system with no mass entering or leaving


 * Open System : A system with mass entering or leaving


 * Isolated System : A system with no mass or energy entering or leaving


 * State : A set of conditions which completely define a system
 * A state is given by its volume, temperature, pressure, and amount (moles) or mass


 * Extensive Property : A property dependent on the amount of material
 * For example, total volume: if we add two 250 mL cups of water together we get 500 mL of water


 * Intensive Property : A property not dependent on the amount of material
 * For example, temperature: if we add two 250 mL cups of 30 &deg; C water together the result is 30 &deg; C water, not 60 &deg; water


 * Pressure : Force divided by the surface area it is applied to
 * SI unit is the Pascal (Pa) = 1 N/m2


 * Standard State Pressure : 1 bar
 * 1 bar = 105 Pa
 * previously 1 atmosphere (atm) was used -- 1 atm = 1.1013 bar


 * Temperature : see the next section