changes of state Flashcards
(10 cards)
1
Q
describe MOVEMENT of liquid particles
A
random directions but are still touching
2
Q
describe convention in cooling tower
A
- due to convection
- air entering from outside is cooler
- heated air expands
- less dense air rises
- cooler air falls
- process is repeated
3
Q
explain how evaporation cools water
A
- temp is proportional to avergage kinetic energy
- energetic particles leave surface
- gas particles have higher average kinetic energy
- average kinetic energy in remaining particles is reduced
4
Q
factors that affect rate of evaporation
A
- temp of liquid
- surface area of liquid
- temperature of surroundings
- humidity of surroundings
5
Q
why does evaporation make someone feel cold
A
- more energetic molecules escape
- less energetic molecules remain
- thermal energy is transferred from the persons body
- evaporation requires the heat of vaporisation
6
Q
what is the unit of mass needed for a q = mct question
A
KG
7
Q
define specific heat capacity
A
the amount of energy required to raise the temperature of 1 kg of the substance by 1 degree celcius
8
Q
specific heat capacity practical steps
A
-measure current and voltage to work out power
- measure temp increase and time taken
- find total energy as e = pt
- measure mass of substance
-use balance
- plot on temp time graph
8
Q
errors possible for this practical
A
- ensure digital balance is at 0
- stir water constantly
9
Q
A
