Area of study 1: Chapters 1/2 (heating processes/moving heat around)

Question 1

What is heat?

Answer 1

The transfer of thermal energy from a hotter body to a colder one

Question 2

What is internal energy

Answer 2

the total amt of kinetic and potential energy of the particles

Question 3

What can heat result in?

Answer 3

1. increase in temp - net gain of kinetic energy
2. state change - potential energy increased
3. expansion of object - potential energy increased

Question 4

What occurs at absolute zero?

Answer 4

particles stop moving at -273 celsius

Question 5

K ➡️ C?

Answer 5

-273

Question 6

C ➡️ K?

Answer 6

+273

Question 7

What is specific heat capacity?

Answer 7

it is the amount of energy required to raise 1kg of the substance by 1C

Question 8

Higher heat capacity?

Answer 8

= greater amt of energy to raise temp. absorbs a lot more heat before it actually begins to get hot

Question 9

What is latent heat?

Answer 9

energy released/absorbed during a phase change

Question 10

difference between fusion and vaporisation latent heat

Answer 10

fusion = melting = energy added so temp increase (solid - liquid)

vaporisation = boiling (liquid - gas)

Question 11

when a substance is undergoing phase change, why does the temperature not increase?

Answer 11

instead of temp increase, the energy increases the potential energy of the particles, reducing the interparticle forces - extra energy is used in reducing forces btw particles

Question 12

What is evaporation?

Answer 12

the changing of a liquid into vapour at a temp under boiling point

Question 13

How does evaporation occur?

Answer 13

if the liquid particles have sufficient energy, they can escape through the surface of the liquid into the air. the higher energy particles escape leaving the lower-energy particles behind which results in the overall kinetic energy decreasing

Question 14

Evaporation occurs faster in what type of liquids?

Answer 14

volatile ones - such as perfume. the surface bonds are weaker

Question 15

how does sweating work?

Answer 15

the skin is hot due to work done by it. when one sweats, the energy from the skin is transferred onto the sweat particles, resulting in those heating up. this then results in the higher energy particles to escape, decreasing the temp

Question 16

Dogs don’t sweat like humans do, after exercising they pant to cool down. When dogs pant they stick out their wet tongue and blow air over it. Explain how the action of panting helps the dog cool down.

Answer 16

1. air passing by increases rate of evaporation
2. dog is hot (heat) - heats up particles
3. saliva heats up, takes that heat from dog which evaporates
4. this cools down dog by removing heat

Question 17

how can evaporation be increased?

Answer 17

1. volatility of substance
2. surface area: greater area exposed to air
3. temp: hotter substance evaporate quicker
4. air movement: breeze blowing over increases evaporation

Question 18

where is evaporation decreased?

Answer 18

humid places

Question 19

what things influences a change in temp:

Answer 19

1. mass
2. material
3. amt of energy transferred

Question 20

what is work?

Answer 20

energy transferred by the action of force

Question 21

conduction is?

Answer 21

the transfer of heat energy through a substance by particle collision with no net movement of particles.

Question 22

convection is?

Answer 22

the transfer of heat energy by bulk movement of particles.

Question 23

radiation is?

Answer 23

is the transfer of energy without a medium.

Question 24

methods of conduction?

Answer 24

1. collision of atoms
2. delocalised electrons

Question 25

how does conduction occur through collision of atoms?

Answer 25

in a solid, particles are constantly vibrating. when heated up, the particles vibrate more and these interactions pass on the kinetic energy.

its slow

Question 26

how does conduction occur through delocalised electrons?

Answer 26

when heated, the cations and electrons gain energy. electrons provide a means by which energy can be transferred quickly

Question 27

what affects thermal conductivity?

Answer 27

1. surface area: greater surface area relative to volume = higher rate of conduction
2. temp diff: greater diff between two substances = quicker energy transfer

Question 28

how does convection work?

Answer 28

1. transfer of heat energy by bulk movement of particles
2. the cooler, more dense water at the top sinks
3. the warm, less dense water at the bottom is displaced upward by it

Question 29

how to stop convection?

Answer 29

to stop, heat from the top

Question 30

What is a sea breeze?

Answer 30

occurs at day.
1. both sea and land are warmed
2. warm air from land rises
3. rising air helps form clouds
4. cooler air sinks
5. sea breeze

Question 31

what is land breeze?

Answer 31

breeze from land towards sea. formed at night when sea and land lose heat. land specific heat capacity is lower, loses heat quicker than sea. sea it warmer, sends air up, cool air sinks, land breeze.

Question 32

example of conduction?

Answer 32

heat transfer from coffee cup to hand

Question 33

example of convection?

Answer 33

steaming cold milk to make coffee - kettle

Question 34

example of radiation?

Answer 34

sunlight - microwave

Question 35

3 ways interactions with radiation can occur:

Answer 35

1. emit radiation
2. absorb
3. transmit

Question 36

higher temp of object =? (radiation)

Answer 36

higher temp = higher frequency = shorter wavelength

Question 37

what affects the emission and absorption of radiation?

Answer 37

1. surface area: larger surface area = more
2. temp - greater temp diff = more
3. surface colour/texture - black surfaces emit radiant heat faster than a shiny/light one