changes of state and SLH Flashcards
what is internal energy?
the total energy that its particles have in their kinetic and potential energy stores
what increases internal energy?
heating the system transfers energy to its particles
what happens when internal energy increases?
leads to a change in temperature or change in state, the size of the change depends on the mass of the substance, what its made of and the energy input
when does a change of state occur?
if the substance is heated enough the particles have enough energy in their kinetic energy stores to break the bonds holding them together
what are the changes of state?
freezing, melting, evaporating, condensing and sublimating
what is a change of state?
a physical change, meaning you don’t end up with a new substance
what happens to the mass and the number of particles?
it doesn’t change
what is the energy used for when changing state?
breaking intermolecular bonds not changing temperature
how is the change in internal energy shown on a temperature graph?
a flat line because it doesn’t change temperature
what is specific latent heat?
the amount of energy needed to change 1kg of a substance from one state to another without a temperature change
what is SLH different for?
different materials
what is SLH for melting or freezing called?
specific latent heat of fusion
what is SLH for evaporating or condensing called?
specific latent heat of vaporisation
how do you calculate the energy needed for a substance to change state?
energy = mass x SLH
example: the SLH of vaporisation of water is 2260000 j/kg, how much energy is needed to boil 1.50 kg of water at 100 degrees?
1.50 x 2260000 = 3390000J
