Topic 3 Paricle Model Of Matter

Question 1

Why do solids usually have a very high density?

Answer 1

Particles are packed closely together-lot of mass for their volume

Question 2

Why do liquids usually have a high density?

Answer 2

Particles are close together-lot of mass for their volume

Question 3

Why do gases have a low density?

Answer 3

Particles are very far apart-small mass for their volume

Question 4

What is internal energy?

Answer 4

The total kinetic energy and potential energy of all the particles that make up a system

Question 5

What is sublimation?

Answer 5

When a solid turns directly to a gas

Question 6

What does the density of an object depend on?

Answer 6

What it’s made of and how it’s particles are arranged

Question 7

How are the particles in a dense material arranged?

Answer 7

Packed tightly together

Question 8

Why do gases usually have low densities?

Answer 8

Almost no forces of attraction between particles (particles not close together)

Question 9

What happens if you reverse a change of state?

Answer 9

Substance return to its original form and original properties

Question 10

What is conserved in a change of state?

Answer 10

Mass

Question 11

What is internal energy?

Answer 11

Total kinetic energy and potential energy of all particles that make up system

Question 12

How does heating change the energy stored within a system?

Answer 12

Transfers energy to its particles, gain energy in kinetic stores and move faster, increases internal energy

Question 13

What are the 2 possible outcomes of heating a system?

Answer 13

Raises temperature or change in state

Question 14

What are the 3 things that a change in temperature of a system depends on?

Answer 14

Mass of substance heated
What it’s made of (specific heat capacity)
Energy input

Question 15

When will a change in state occur?

Answer 15

Particles have enough energy in kinetic stores to break bonds

Question 16

What is the energy needed to change the state of a substance called?

Answer 16

Latent heat

Question 17

What is specific latent heat of a substance?

Answer 17

Amount of energy needed to change state of 1kg of substance without changing its temp

Question 18

What is specific latent heat for cooling?

Answer 18

Energy released by change in state

Question 19

What is the specific latent heat different for?

Answer 19

Different materials and for changing between different states

Question 20

What is the specific latent heat of changing between a solid and a liquid (melting or freezing) called?

Answer 20

Specific latent heat of fusion

Question 21

What is the specific latent heat for changing between a liquid and a gas (evaporating/boiling/condensing) called?

Answer 21

Specific latent heat of vaporisation

Question 22

What is the formula for specific latent heat?

Answer 22

Energy = mass x SLH

Question 23

What are the units for specific latent heat?

Answer 23

J/kg

Question 24

What is happening when a substance is melting or boiling?

Answer 24

Increased internal energy used for breaking bonds between particles (not raising temp)

Question 25

What is happening when a substance is condensing or freezing?

Answer 25

Bonds forming between particles, releases energy, internal energy decreases

Question 26

When a substance is condensing or freezing, what does the temperature not go down until?

Answer 26

All substance turned to liquid/solid

Question 27

What happens if you increase the temperature of a gas?

Answer 27

Transfer energy to kinetic energy stores of particles, average speed of particles increases

Question 28

What is the temperature of a gas related to?

Answer 28

Average energy in kinetic energy stores of particles

Question 29

What do gas particles do when they collide with something?

Answer 29

exert a force- pressure

Question 30

What is the outward gas pressure in a sealed container?

Answer 30

Total force exerted by all particles in gas on unit area of container walls

Question 31

Why does increasing the temperature of a gas increase the pressure (if volume kept constant)?

Answer 31

Faster particles, more frequent collisions, increase in net force

Question 32

What happens if the volume of a gas is increased and the temperature kept constant?

Answer 32

Particle more spread out, hit container walls less often, gas pressure decreases

Question 33

What is the relationship between pressure and volume?

Answer 33

Inversely proportional

Question 34

What is the relationship between pressure and volume for a gas of fixed mass at constant temperature?

Answer 34

pV = constant

Question 35

What does the pressure of a gas cause?

Answer 35

Net outwards force at right angles to surface of its container

Question 36

Why is there also a force on the outside of a container?

Answer 36

Pressure of gas around it

Question 37

If a container can easily change its size what can a change in pressure cause?

Answer 37

Container to compress or expand due to overall force

Question 38

What is an example of a container that can be compressed or expanded?

Answer 38

Helium balloon

Question 39

What does doing work (transfer of energy by a force) on a gas do?

Answer 39

Increases its internal energy, increases its temperature

Question 40

Why does doing work on a gas using a bike pump lead to an increase in temperature of the gas?

Answer 40

Gas applies pressure to plunger of pump, exerts force on it, work has to be done against force to push down plunger, transfers energy to kinetic stores gas particles