P1.2 changes of state Flashcards
Why does mass stay the same in changing of state?
Because the number of particles don’t change only rearranged
Explain chemical change
- Formation of new chemical substances
- hard to reverse
Explain physical change
- Molecules rearranged
- easy to reverse
- melting, boiling, freezing, condensing
Specific heat capacity
The specific heat capacity of a substance is the amount of energy needed to raise the temperature of one kilogram of a substance by one degree
Specific latent heat
The specific latent heat of a substance is the amount of energy needed to change the state of 1 kilogram of a substance with no change in temperature
What is the specific latent heat of fusion
Change of state from solid to liquid
Specific latent heat of vaporisation
Change of state from liquid to gas
Specific heat capacity equation
Specific heat capacity = change in thermal energy/(mass× Change in temperature)
How to find specific heat capacity of an aluminium block
- Find the mass of the block using an electronic balance
- put a thermometer in the block and record the start temperature
- connect an ammeter in series and a voltmeter in parallel to the immersion heater
- Connect a power supply to the circuit
- turn the power supply on and start the stopwatch
- record current and potential difference
- after five mins turn of power supply and record the final temp of the block
- Find energy=current
- Specific heat capacity = change in thermal energy/(mass× Change in temperature)
Specific latent heat equation
Thermal energy for a change of state/mass= specific latent heat
What effect does heat have on the energy stored in a system
- Heat increases temperature
- as temperature increases so does the kinetic energy of particles
- causing them to move faster
Limitations of SHC of aluminium block
- Heat escapes to surroundings-so insulate aluminium
*
