Energy Transfer by Heating

Question 1

What is conduction of heat energy?

Answer 1

The process where vibrating particles pass on their extra kinetic energy to neighbouring particles

Question 2

When does conduction usually happen faster?

Answer 2

In denser solids

Question 3

Why does conduction happens faster in denser solids?

Answer 3

Particles are closer together, so they collide more often and pass energy between them

Question 4

What type of structure does an insulator have?

Answer 4

Larger spaces between their particles, so they conduct heat energy more slowly

Question 5

What makes metals good conductors?

Answer 5

Free (delocalised) electrons

Question 6

At the hotter end of a piece of metal, what are electrons doing?

Answer 6

Moving faster and colliding with other free electrons- transferring energy

Question 7

How does heat energy move from the hot end of metal to the cool end?

Answer 7

By electrons colliding and transferring energy

Question 8

In which states of matter does convection occur?

Answer 8

Liquids and gases- FLUIDS

Question 9

What is convection?

Answer 9

When more energetic particles move from hotter regions to cooler regions, taking their heat energy with them

Question 10

Name 3 appliances that convection is used in

Answer 10

Kettles, hot water tanks, convector heaters (all have an immersion heater)

Question 11

What is heat energy transferred from in an immersion heater?

Answer 11

The heater coils

Question 12

When the water particles in an immersion heater get more energy, what do they do?

Answer 12

Move around faster, meaning there’s more distance between them- so the water expands and becomes less dense

Question 13

What does the hotter, less dense water rise above?

Answer 13

The cooler, denser water

Question 14

What does the cooler, denser water do?

Answer 14

Get heated by the coils- giving it energy

Question 15

What are convection current all about?

Answer 15

Changes in density

Question 16

What is condensation?

Answer 16

Is when a gas cools, causing the particles to lose kinetic energy, and the attractive forces between particles increases, forming a liquid

Question 17

What’s evaporation?

Answer 17

When particles escape from a liquid

Question 18

When can particles in a liquid evaporate?

Answer 18

When they travel in the right direction, and if they are travelling fast enough (KE) to overcome the attractive forces of other particles

Question 19

Which particles are most likely to evaporate?

Answer 19

Fastest ones, they have the most kinetic energy

Question 20

When particles evaporate, what happens to the average speed and kinetic energy of the remaining particles?

Answer 20

It decreases

Question 21

When is the cooling effect caused by evaporation useful?

Answer 21

When you sweat, it evaporates and cools you

Question 22

What does the decrease in average particle energy cause?

Answer 22

Temperature to decrease

Question 23

What 4 factors effect the rate of evaporation?

Answer 23

Temperature, density, surface area, airflow over the liquid

Question 24

How does a higher temperature increase the rate of evaporation?

Answer 24

Average particle energy is higher, more have the energy to escape

Question 25

How does a lower density increase the rate of evaporation?

Answer 25

Forces between particles are weaker, so more particles have the energy to escape

Question 26

How does a larger surface area increase the rate of evaporation?

Answer 26

More particles are near the surface, so they can escape

Question 27

How does a greater airflow over the liquid increase the rate of evaporation?

Answer 27

Lower concentration of evaporating substance in the air, as the air above the liquid is being replaced above the liquid more quickly

Question 28

What 4 factors effect the rate of condensation?

Answer 28

Temperature of the gas, temperature of the surface the gas touches, density, airflow

Question 29

How does the temperature of the gas being lower increase the rate of condensation?

Answer 29

Average particle energy in the gas is lower, so more particles slow down enough to clump together and form liquid droplets

Question 30

How does a higher density increase the rate of condensation?

Answer 30

Forces between particles are stronger, so fewer particles have the energy to overcome the forces and will instead clump together to form a liquid

Question 31

How does a lower airflow increase the rate of condensation?

Answer 31

Concentration of the substance in the air will be higher, so the rate of condensation is greater

Question 32

Does a higher or lower temp. of the surface the gas touches increase the rate of condensation?

Answer 32

Lower

Question 33

What 3 things does the rate an object transfers heat energy depend on?

Answer 33

Surface area and volume, material an object is made from, the nature of a surface with which the object is in contact

Question 34

What does a bigger temperature difference between an object and its surroundings increase?

Answer 34

The rate at which energy is transferred by heating

Question 35

When talking about animal adaptations, what should you look out for on a diagram?

Answer 35

Ear size, thickness of fur, SA to volume ratio