Topic 14: particle model

Created by

Mollie

Cards (31)

what does density depend on?
spacing of the atoms in matter
order of densities in solids liquids and gases
solids - little space between particles
liquids - small gaps - random arrangement (except ice and water)
gases - lots of energy, volume increases, density increases
what is conserved during changes in state
mass
what are the 5 changes in state
melting - solid to liquid
evaporation- liquid to gas
condensing - gas to liquid
freezing - liquid to solid
sublimation - solid to gas
why are changes in state not chemical changes
the material retains its original properties when the reaction is reversed
what happens when you heat a system
particles have more energy
vibrate more
temperature of system increases or changes state
what is specific heat capacity
energy required to raise the temperature of 1kg of a substance by 1 degree
what is specific latent heat
energy needed to change the state of 1kg of a substance without a change in temperature
what is specific latent heat of fusion
the energy needed to melt or freeze
what is specific latent heat of vaporisation
Energy needed to boil or condense
when is energy absorbed in state changes
melting and evaporating
when is energy released in state changes
freezing and condensing
what is the purpose of insulation
to prevent thermal energy transfers out of the system to avoid it being wasted and lost to the surroundings
how does reflective coating insulate
reflect infrared radiation or heat back into the system
what does pressure produce
a net force at right angles to any surface
how does velocity change in a gas
as particles collide with the wall as they change momentum during the collision
how is a force exerted in a gas
onto the wall of the container
how does temperature impact the pressure of a gas
more energy given to particles
Thermal energy transferred to kinetic
Particles move faster
Collisions occur more
Particles exert more force
Pressure increases
what is absolute zero
0 kelvin or -273 degrees Celsius - nothing exsists at a colder temperature than this
Why can nothing exists at a colder temperature than absolute zero
Particles have no energy and do not vibrate at all
how do you convert kelvin to centigrade
degrees to kelvin = + 273
kelvin to degrees = - 273
Why are ice and water exceptions to normal substances
Most become denser when they freeze
water freezes in a hexagonal structure with more empty space
volume increases and mass stays the same decreasing density
What is conservation of mass
The mass stays the same in all strategy changes as the number of particles stay the same only arrangement changes
What is the difference between specific latent heat and specific heat capacity
in SHC energy is used to increase the kinetic energy causing a temperature change (focus on temperature)
In SLH energy is used to overcome intermolecular forces (focus on changing state)
What is the relationship between temperature and pressure at a constant volume
Pressure increases as temperatire increases
how to investigate SHC of water
use immersion heater to heat a known mass of water
record the temperature changed and energy supplied with a joule-meter or using power x time
use energy = mass x SHC x time
how to investigate ice melting
thermometer in beaker of ice
record the temperature every minute until above 0
plot a graph
what should a graph of ice melting look like
initial rise as ice warms
flat as ice melts because it stays at a constant temperature while melting
final rise as the liquid heats
what determines whether an increase in temperature happens or an overall state change
whether particles only gain energy or there is enough to break the bonds which depends on:
mass
material
energy input
SHC
how to investigate the density of irregular shapes
measure mass
measure volume with eureka can using displacement in cylinder
use D = m/v
how to investigate the density of a liquid
measure volume with measuring cylinder
mass by mass of empty beaker - mass of liquid + beaker
use d = m/v