Thermal Energy Transfer Flashcards
Internal Energy
The sum of all of the kinetic energies and potential energies of all it’s particles.
How to increase Internal Energy?
Do work on the system to transfer energy to it (moving the particles).
Increase temp of system.
When the state of a substance is changed, its internal energy also changes, Why?
Potential energy of the system changes, while kinetic energy is kept constant.
Demonstrate internal energy changing with state of substance
When water boils at 100 degrees, after that the energy gained through heating is used to break bonds between the water molecules to change state, so potential energy increases.
Amount of energy required to change temp of a substance
Q = m x c x change in temp
Specific Heat Capacity
Amount of energy required to increase the temp of a 1kg substance by 1 degrees celsius.
Amount of energy required to change state of a substance
Q = m x l (specific latent heat)
Specific Latent Heat
Amount of energy required to change the state of 1kg of a material, without changing its temp.
Specific latent heat of fusion
solid to liquid
specific latent heat of vaporisation
liquid to gas.
How long will it take for X to reach X degrees?
- Write out all values.
- Find energy required (Q = m x c x temp change)
- Find time taken = P/Qt —> t = Q/P
Unit for SHC
J Kg^-1 K^-1 (or degreed celsius ^-1)
Closed System
Doesn’t allow any transfer of matter in or out.
Total internal energy is constant, no energy transferred.
Temp Change Formula
Q/mc
To find final temp just add result to initial temp.
Energy Change Formula (SLH)
SLH x mass of substance changed
