p6 - molecules and matter Flashcards
define density
mass per unit volume
give units and symbol for density
units: km/m(3) or g/cm(3)
symbol: p
how do you know if an object will float in water?
objects with a density less than the density of a given liquid will float in that liquid e.g: objects with a density less than 1000kg/m(3) will float in water
what is the volume of a cuboid formula?
a x b x c
define melting point
temperature at which a solid changes to a liquid
define freezing point
same temperature at which liquid changes to a solid
define boiling point
temperatue at which loquid changea to.a gas (same temp as condensation)
define the latent heat
the energy transferred to or from a substance
define internal energy of a substance
total energy in the kinetic energy store and potential energy store of the particles in the substance
where is the kinetic energy from?
due to individual motions relative to eachother
where is the potential energy from?
due to individual positions relative to eachother
what happens when a substance is heated?
energy of particles increases, so internal energy increases
what happens if the total kinetic energy of the particles increases?
temperature of the substance increases
what happens if a substance changes state?
potential energy of its particles increases
what happens when a solid is heated?
when a solid is heated, the particles’ energy stores increase and they vibrate more
what happens when a liquid is heated?
some particles gain enough energy to break away from the other particles and are in a gas state
what happens when a gas is heated?
particles gain kinetic energy and move faster
what happens when gas molecules are in a box?
- particles in a gas collide with eachother and with the walls of their container
- during these particles exert a force and hence a pressure on the walls of the container
define the latent heat of fusion
energy required by a substance to change from a solid to a liquid, with no change in temperature
in what conditions is latent heat transferred to surroundings?
if a substance is cooled and changes from a liquid to a solid
define the specific latent heat of fusion
energy needed to change 1 kg of the substance from a solid to a liquid, with no change in temperature
give equation for specific latent heat of fusion
specific latent (J/kg) = energy (J) / mass (kg)
