Year 11 Physics - Heating Processes

describe moevement of particles in solids

they vibrate only, do not translate (move position)

describe movement of particles in liquids

particles can translate due to a few broken intermolecular bonds

describe movement of particles in a gas

particles can translate due to majority of molecular bonds being broken

what is solid to liquid change

melt

what is liquid to gas change

evaporate/boil

what is gas to liquid change

condense

what is liquid to solid change

Freeze/solidify

what is solid to gas change

sublimation

what is gas to solid change

deposition

what is internal energy

the total kinetic and potential energy of a substance

what is kinetic energy

hwo much the particles within a substance vibrate (how quickly)

what is potential energy

how far away the partcles within the substance are from each other

how is kinetic energy measured

temperature

what is temperature

average kinetic energy of particles within the substance

how is potential energy measured

expansion of a substance

what is heat

the transfer of thermal energy from one substance to another due to a difference in temperature

what is thermal equilibrium

the point where 2 substances are the same temperature

how do you convert \*C to K

add 273

how do you convert K to \*C

subtract 273

what is a joule

the amount of energy required to lift 100g of a substance 1 metre

KJ to J

x 1000

MJ to J

x 10^6

what is work

the change of energy frm one form to another

what is specific heat capacity

the amount of energy required to raise the temeperature of 1kg of a substance by 1\*C or 1K

what is the formula for the amount of energy needed to change a substances temperature

Q=mcΔt

are mass and required thermal energy proportional? why?

yes, because the larger the mass, the more energy required to heat it

do all substances have the same SHC

no they are all unique

what is latent heat

the amount of energy required to change 1kg of a substance from one state to another, without a change in temperature

what is the latent heat formula

Q=mL

does temperature increase during heating? why? what about potential energy?

yes, because the energy increases vibrations which is kinetic energy and temperature is average kinetic energy. potential energy remains constant

does temperature increase during the change of state? why? what about kinetic energy

temperature remains constant during changes of state beause the energy is increasing the distance between particles, which is potential energy, not the vibrtations of partciles. this means kinetic energy remains constant

what is fusion and vaporisation

fusion is liquid to solid or solid to liquid, and vaporisation is gas to liquid or liquid to gas

is fusion or vaporisation latent heat higher

vaporisation

what is conduction

transfer of energy between substances due to the substance particles touching/colliding and transferring energy between them and heating the cooler substance

name a good conductor and an insulator and why

good conductor is metal, due to delocalised electrons and an insulator is air as the particles are so diffuse, its hard for them to collide efficiently

what is convection

bulk movement of liquid or gas. it occurs when a substance heats, making it less dense and rise, as it rises it pushes the cooler substance down as it is more dense. the cooler substance then heats and the cycle repeats

what is radiation

the emission of electromagnetic waves/photons by all substances over absolute zero, and other substances absorb the emitted energy

does radiation need matter

no, but all other transfers do

explain properties of different colours

black = best absorber and emitter, but bad reflector (absorbs all light wavelengths)

white = best reflector but bad emitter and absorber (reflects all light wavelengths)

why does evaporation cool a substance

the higher energy particles leave the substance, meaning the average kinetic energy of the substance decreases hence temperature lowers

how does a thermos prevent heat transfer

sealed plastic lid → prevent convection to air and is poor conductor

reflective glass walls → poor conductors and reflect radiation

vacuum between walls → stops conduction and convection

plastic/ metal outer → poor conductor or reflects incoming radiation

3 layers → hold liquid

insulation → poor conductor

stabilisers→ prevent inner touching outer, minimise conduction and stabilise inner

how does a fridge work

1. compressor compresses refrigerant and it is released at a higher temperature and higher pressure
2. refrigerant pushed into condensor coil where heat is exchanged with air outside
3. refrigerant becomes a liquid from a vapor as it exchanges heat with air
4. refigerant goes into evaporation coils inside fridge
5. refrigerant absorbs heat from inside fridge
6. refregerant evaporates to a gas a goes back to compressor
7. cycle repeates