9 Thermodynamics Flashcards
Heat
Energy transfer from a body or region of high temperature to one of lower temperature
Internal energy
Sum of kinetic energy of the molecules within a body and the potential energy of the bonds between the molecules
Specific heat capacity
The energy transfer needed to change the temperature of 1kg of a substance by 1K
Equation linking energy, mass, specific heat capacity and change in temperature
E = m x c x change in temp (theta)
Equation linking power, mass, specific heat capacity, temperature, time and charge (learn)
P = mc x change in temp/time + charge/ time
How can steady state conditions be kept
A thermistor can be used as part of a potential divider circuit. When the temp decreases, the resistance in the thermistor increases and so more voltage passes through the potential divider and turns the switch on. When the temp increases the opposite occurs.
Specific latent heat of fusion
The energy needed to convert 1kg of a solid to liquid without change in temp
Specific latent heat of vaporisation
The energy needed to convert 1kg of a liquid to a gas without change in temperature
Equation for specific latent heat
L = E/m
Boyle’s law (learn)
P1 x V1 = P2 x V2
at constant temperature
Charles’s law (learn)
V1/t1 = V2/t2
At constant pressure
The pressure law (learn)
P1/t1 = P2/t2
At constant volume
What are ideal gases?
Gases that obey boyles law at all temps and pressures so will never liquefy. This means the internal energy is entirely kinetic as there is no potential energy between bonds in gases
Equation of state (learn)
pV = nRT
P= pressure V= volume n=moles of a gas R= universal molar gas constant 8.31 T= temperature
Equation linking pressure, volume, temperature, number of molecules in gas
pV = NkT
p= pressure V= volume N= no of molecules in gas k= Boltzmann constant 1.38 x 10^-23 T= temperature