P1 6 Particles Flashcards
state the equation for specific heat capacity
change in energy = mass x SHC x change in temp
∆E = m x c x ∆θ
(J) (kg) (J/kg) (°C)
define specific heat capacity
the amount of energy needed to change the temperature of 1kg of a substance by 1 degree C
describe the method for RP: measuring specific heat capacity of a material
- measure the mass of material block with a balance
- set up apparatus: place immersion heater in central hole at top, place thermometer into smaller hole and put a couple of drops of oil in as lubrication, wrap block with insulation
- measure the initial temp of block using thermometer
- connect heater to joulemeter+ power supply and turn on, heat block for 10mins
- measure final temp using thermometer and calculate change in temp
- measure change in energy using joulemeter
- calculate specific heat capacity (c = ∆E / m x ∆θ)
describe why insulation around the block is required in calculating specific heat capacity RP
- reduces dissipation
- if dissipation occurs, the change in energy value will be too high
-> so SHC value will be too high
describe the methods (2) for RP: calculating density of irregular solid objects
- measure mass of object using balance
- fill eureka can with water
- make water level with spout
- place object in water
- collect displaced water in a measuring cylinder
- volume of water in measuring cylinder = volume of object
- calculate density using mass / volume
OR - measure mass of object using balance
- fill measuring cylinder with water so object will be submerged
- record starting volume of water
- place object in water
- record new volume of water
- new volume - starting volume = volume of object
- calculate density using mass / volume
describe the method for calculating density of a regular solid object
- measure length, width and height of object using a ruler
- calculate volume by multiplying all figures together
- measure mass of object using a balance
- calculate density = mass / volume
state the equation for density
density = mass / volume
p = m / V
(kg/m³) (kg) (m³)
-> solids+liquids are denser than gases as atoms are closely packed together, so there is a lot of mass in a small volume
state the equation for specific latent heat
change in energy = mass x latent heat
∆E = m x L
(J) (kg) (J/kg)
define specific latent heat
amount of energy required to change the state of 1kg of a substance without a change in temp
solid-liquid : SLH of melting
liquid-gas : SLH of vaporisation
describe the two things that happen to an object when heated
increase in thermal energy store of object and either:
* change of state (specific latent heat)
* change of temperature (specific heat capacity)
define sublimation
change of state from solid to gas
define deposition
change of state from gas to solid
describe how to increase gas pressure in a container
- decrease volume of the container - distance for particles to travel is reduced so there are more collisions per second with the container walls+ other particles
- increase temperature - particles gain more kinetic energy so move faster+ exert greater force on container walls+ more collisions occur
describe the arrangement+motion of particles in a solid
- packed tightly together
- in orderly rows - regular arrangement
- high density
- vibrate in fixed positions
- solids have a fixed shape as particles cannot move from place to place
- cannot be compressed+ have a fixed volume as particles have no space to move to
- due to strong attractive forces between particles
describe the arrangement+motion of particles in a liquid
- loosely packed - particles can move freely
- random arrangement
- liquids can flow+ take the shape of their container as particles can move past each other
- cannot be compressed+ have a fixed volume as particles keep close contact+ have no space to move to
- due to weaker attractive forces (than solids) between particles
describe the arrangement+motion of particles in a gas
- particles are far apart
- random arrangement
- move quickly at different speeds+ different directions
- due to weak attractive forces between particles
- completely fill their container as particles move in all directions+ aren’t touching
- no fixed shape or volume
- can be compressed as particles have space to move to - low density
state limitations of the particle model for solids/liquids/gases
- particles are not actually solid spheres
- forces between particles are not represented
