19.3 Flashcards
what is the melting point
well defined temp at which a pure substance melts
when does a liquid boil
at its boiling point
why is a gas less dense than a solid and a liquid
this is because the solid and liquid molecules are more tightly packed together in contact with eachother
why can liquids and gases flow but solids can’t
the atoms in a solid are locked togeter by strong force bonds
liquids and gases aren’t locked together because there kinetic energies are too high
what is the energy needed to melt a solid at its melting point called
latent heat of fusion
why is latent heat hidden
there is no change in temp
what is the energy needed to vaporise a liquid called
latent heat of vaporisation
hat is the process of a solid vaporising straight into a gas
sublimation
what needs more energy fusion or vaporisation
vaporisation
definition of specific latent heat of fusion
the energy needed to change the state of a unit of mass of the substance from solid to a liquid without a change of temp
definition of specific latent heat of vaporisation.
the energy needed to cha ge the stat of a unit of mass of the substance from a liquid to a vapour without a change in temp
what’s the energy required change the state of a mass given by
q = ml
l= latent heat
what happens when a solid is heated at its melting point
its atoms vibrate so much the bonds break and they break free
the solid therefore becomes a liquid due to the energy that was supplied
what is released when a liquid solidifies
latent heat
why is latent heat released when a liquid solidifies
slow down as the liquid cools allowing the force bonds to lock the molecules back together
some of the latent heat is realised to keep the temp the same whilst the liquid solidifies
what happens when a liquid is heated at its boiling point
molecules gain enough energy to overcome bonds
molecules break free from each other causing bubbles of vapour
what is realised when vapour condenses
latent heat
molecules slow down and the force bonds pull them together
what is power rate on an energy time graph
p = m c change in T / t
