solids- strong forces of attraction(bonds), vibrate in a fixed position, have definite shape and volume
liquids- weak forces of attraction, free to move around, fairly compact, don't have definite shape but have definite volume
gases- very weak forces of attraction, free to move around by themselves, don't have definite shape or volume
changes of state
from solid to liquid - melting - particles gain more energy and start to vibrate more which weakens forces of attraction/ bonds between them. At the melting point they will have enough energy to break free of their bonds and melt into a liquid
from liquid to gas - boiling - particles move around faster . Gas particles may expand or increase pressure in a container
from gas to liquid - condensing
from liquid to solid - freezing
density
density = massdivided by volume
Density (kg/m cubed) is a measure of how much mass (kg) a substance has per unit of its volume (m cubed)
To convert g/cm3 to kg/m3 you have to:
multiply the g/cm3 value by 1000
required practical - finding the density of a regular object
measure the mass of the solid on the mass balance
measure the length, width, height using a ruler
calculate the volume of the block
calculate density = mass / volume
required practical - finding the density of an irregular object
measure the mass of the object using a mass balance
fill the eureka can with water up till it's at level with the spout
carefully lower the object into the can
check the volume of water that came out of the eureka can into the measuring cylinder
calculate density = mass / volume
required practical - finding the density of a liquid
record the mass of an empty measuring cylinder
measure the mass of 100cm3 of water in a measuring cylinder
subtract the mass of the cylinder from the mass of cylinder and water
calculate density = mass / volume
repeat the experiment a few times to find a mean
specific latent heat is the energy required to change the state of 1kg of a particular substance without a change in temperature
specific latent heat of cooling is the energy released to change the state of 1kg of a particular substance without a change in temperature
The specific latent heat of fusion refers to when a substance changes from a solid to a liquid (or vice versa).
The specific latent heat of vaporisation refers to when a substance changes from a liquid to a gas (or vice versa).
specific latent heat equation
energy (J) = mass (kg) x specific latent heat (J/kg)
pressure is continuous force exerted by particles on or against an object by colliding against it
pressure = force / area
pressure depends on how many collisions there are, how much energy each collision involves
how temperature affects pressure
heat transfers energy to the particle's kinetic energy stores
faster movement of particles causing more collisions
each collision will involve more force
how temperature affects pressure
increase the number of particles and keeping the volume of the container the same
this will ensure there are more particles to collide with the walls and therefore more collisions
how volume affects pressure
a smaller container with the same volume of particles which means less travel is needed
less travel means more collisions
pressure in flexible containers
temperature and concentration will change the volume rather than the pressure as it will expand