thermodynamics Flashcards
define internal energy, U
the sum of the random distribution of kinetic and potential energies within a system of molecules
how to increase the internal energy
- doing work on the substance
- increase thermal energy
how to decrease the internal energy
- doing work from the system to the surrounding (e.g gas pushing piston)
- decrease thermal energy
What is the potential and kinetic energy of a substance
the intermolecular bonds are potential energy; the motion of particles creates kinetic energy
state the relationship between internal energy and temperature
ΔU ∝ ΔT (in kelvin)
does ideal gas have potential energy?
no, there’s no potential energy =>U=Ek
equation of work done when a volume of gas changes at constant pressure
W = p ∆V
w=work done
p=pressure of surrounding
v=volume
what is work done on gas
gas compressed, W=positive
what is work done by gas
gas expands, W=negative
state first law of thermodynamics
∆U = q + W
q=heat transfer to the system
W=work done on the system
what is adiabatic change
when ∆q = 0 => ∆U = W,
what is isothermal change
when ∆U = 0 ==> ∆q = -W, constant temperature
what is isovolumetric change
what W = 0 ===> ∆U = ∆q, constant volume
