Particle Model Of Matter Flashcards
Density
How closely packed the particles are in a solid, liquid, or gas
The amount of mass per unit volume
Density formula
Mass / volume
m / V
Density of irregular shaped object practical
Measure the mass of the stone
Fill the displacement can until the water is level with the bottom of the pipe
Place a measuring cylinder under the pipe
Carefully drop the stone into the can and wait until no more water runs into the cylinder
Measure the volume of the displaced water
Density of water practical
Measure the mass of the measuring cylinder
Pour 50 cm3 of water into the measuring cylinder and measure its new mass
Subtract the mass in step 1 from the mass in step 2
Solid properties
Regular pattern
Fixed position
Vibrate on the spot
Keep their shape
Liquid properties
Random arrangement
Close together
Move around
Takes the shape of a container
Gas properties
Random arrangement
Far apart
Move in all directions
Fill the shape of the container
Kinetic theory of matter - solids
Particles in a solid are held together by strong forces of attraction and vibrate at their position
At low temperatures, the vibration is small and can be considered fixed
When a solid gains energy the particles vibrate more and cause the neighbouring particles to vibrate also
Kinetic theory of matter - liquids
The intermolecular forces within a liquid are too weak to keep particles in a fixed position so they are free to move
They move randomly and so liquids flow
Kinetic theory of matter - gases
The particles in a gas are in constant random motion as there are very weak forces between them
The particles are spaced further apart than in liquids
Evaporation
When particles at the surface of a liquid gain enough energy to leave as a gas
Factors increasing the rate of evaporation
Increasing the surface area of the liquid
Increasing the temperature of the liquid
Condensation
The H2O molecules in the air hit a cold surface and therefore condense, changing state from gas to a liquid
Factors increasing the rate of condensation
Increasing the surface area
Reducing surface temperature
Sublimation
The process by which a solid directly changes to a gaseous state (missing the liquid state).
E.g. dry ice
Internal energy
The total amount of kinetic and chemical potential energy of all particles in a system
Increasing internal energy
Heating a substance will increase its kinetic energy store, and therefore an internal energy change
A change in state causes an increase in potential energy, and therefore an increase in internal energy change
Specific heat capacity
The quantity of energy needed to raise the temperature of a 1kg object by 1°C
Specific heat capacity formula
Change in thermal energy / mass x temperature change
ΔJ / m x ΔT
M = mass (kilogram, kg)
ΔJ = change in thermal energy (joules, J)
ΔT = temperature change (celsius, °C)
Specific latent heat
The amount of energy required to change the state of 1 kilogram of a substance without changing its temperature
Specific latent heat of fusion
Energy needed to change 1kg of a substance from a solid state to a liquid state
Specific latent heat of fusion formula
Energy = mass x specific latent heat of fusion
E = m x Lf
Specific latent heat of vaporisation
Energy needed to change 1kg of a
substance from liquid state to gaseous state
Specific latent heat of vaporisation formula
Energy = mass x specific latent heat of vaporisation
E = m x Lv
Pressure
Force / area
F / A
Factors increasing pressure
As temperature increases pressure increases as;
the average kinetic energy of the molecules increases and therefore the molecules hit the sides of the container more often, increasing the force exerted = more pressure
Boyle’s law
States that for a fixed amount of (ideal) gas at a fixed temperature pressure is inversely proportional to the volume
