Thermodynamics 1

What is an isolated system

no exchange of mater or energy with surroundings

whats a closed system

exchange of heat but not matter with surroundings

whats an open system

exchange of matter and energy with surroundings

whats a property

a particular characteristic of the system

what is an intensive property

These are independent of the amount of material in the system

T and p.

what is an extensive property

depend on the amount of material in the system

what is the 1st law of thermodynamics

energy is neither created nor destroyed but just transformed from one kind to another

whats the mathematic equation for the 1st law of thermodynamics

triangleU = q + w

U = energy

Q = heat

W = work

what does the sign of heat (q) tell us

the direction of heat transfer

if heat is transferred out of the substance and q is negative what is the process

exothermic

if heat is transferred into the substance and q is postive then what is the process

endothermic

what happens when heats added to the system

w = 0

-q = w so triangleU= 0

whats the change in enthalpy of a systen

the heat transferred from the surrounding to the system in a constant pressure

whats heat capacity used for

relate change in enthalpy to a change in temprature

whats the standard state of a substance at a specified temprature

its pure form at a pressure of 1 bar

work equation

w = -p2triangleV

w = work

p2 = final pressure

triangleV = difference in volume

what are 3 things that make a process reversible

• process produces the maximum amount of work

• occurs infinitely slowly

• nearly in a state of equilbrium and small changes reverse the direction

what are 3 things that make a process irreversible

• less than the maximum quanity of work

• occurs rapidly

• small changes do not reverse the process

what is an isothermal process

where temprature remains constant

what is a non isothermal process

where temprature changes throughout

are reversible and irreversible processes isothermal or non isothermal

isothermal