Particle Model of Matter

Question 1

State the different states of matter in order (least to most) of density of atoms

Answer 1

Gas, liquid, solid

Question 2

Describe the particle arrangement of a solid

Answer 2

Tightly packed in a regular arrangement. Particles can only vibrate on the spot

Question 3

Describe the particle arrangement of a liquid

Answer 3

Close together, but with an irregular arrangement. They can flow over each other

Question 4

Describe the particle arrangement of a gas

Answer 4

Separated, with no regular arrangement. Particles can move freely

Question 5

What is always conserved when a substance undergoes a change of state?

Answer 5

Mass

Question 6

How does a change of state differ from a chemical change?

Answer 6

In a change of state, the material can return to having its previous properties if the change is reversed

Question 7

What is sublimation?

Answer 7

When a solid changes into a gas without passing through a liquid state

Question 8

What is the opposite of evaporation?

Answer 8

Condensation, which is when a gas changes into a liquid state

Question 9

What is evaporation?

Answer 9

When a liquid changes into a gas state

Question 10

When water boils in an open pan, why does the mass of the pan of water appear to decrease?

Answer 10

Some of the vapour will evaporate and turn into water vapour. This will leave the pan meaning the mass of the pan will decrease. The mass of the whole system however remains constant

Question 11

Explain the processes involved when a bathroom mirror mists up

Answer 11

Hot water evaporates to form water vapour
This water vapour lands on the cooler mirror
The vapour condenses and returns to liquid state on the mirror’s surface

Question 12

What is the internal energy of a substance?

Answer 12

The energy stored by the particles
The sum of the total kinetic and potential energies that make up the system

Question 13

How does heating affect the energy of a substance?

Answer 13

Heating transfers energy to the substance
It increases the energy of the particles that make up the substance

Question 14

What two things can heating a substance do?

Answer 14

Raise its temperature
Change the state of a substance

Question 15

What three factors determine the temperature change of a system?

Answer 15

Mass of substance being heated
Type of material
Energy inputted into the system

Question 16

State the equation used to calculate the temperature change when a substance is heated. State the units

Answer 16

Change in thermal energy (j) = mass (kg) x specific heat capacity (j/kg) x temperature change (celsius)

Question 17

Define specific heat capacity

Answer 17

The amount of energy needed to increase the temperature of 1kg of a substance by 1 degrees celsius

Question 18

Describe how the internal energy and temperature of a substance changes when a change of state occurs

Answer 18

The internal energy of the substance will be increased or decreased
The temperature of the substance will remain constant

Question 19

Define specific latent heat

Answer 19

The amount of energy needed to change the state of 1kg of a substance with no change in temperature

Question 20

State the equation for the energy required to change state. State the units

Answer 20

Energy to change state (J) = mass (kg) x specific latent heat (J/kg)

Question 21

What is the specific latent heat of fusion?

Answer 21

The energy required to change 1kg of a substance from solid state to liquid state without a change in temperature

Question 22

What is the specific latent heat or vapourisation?

Answer 22

The energy required to change 1kg of a substance from liquid state to gas state without a change in temperature

Question 23

Describe the motion of molecules in a gas

Answer 23

They are in constant random motion

Question 24

What factor affects the average kinetic energy of gas molecules?

Answer 24

The temperature of the substance
The higher the temperature, the higher the average kinetic energy of the molecules

Question 25

What effect does increasing temperature have on the pressure of a gas when held at constant volume?

Answer 25

Pressure of the gas will increase as the temperature increases

Question 26

Why does pressure increase as temperature increases?

Answer 26

Kinetic energy of molecules increases
Collisions of molecules become more frequent
Greater rate of change of momentum
Greater force and therefore pressure

Question 27

If gas A is at a low pressure, and gas B is at high pressure, what can be said about the rate of collisions in each gas?

Answer 27

There are more collisions per second in gas B than in gas A
The rate of collisions is higher in gas B

Question 28

Describe the force that the pressure of a gas exerts on the walls of its container

Answer 28

The net force acts at right angles to the container’s surface
The force increases as pressure increases

Question 29

Explain how increasing the volume of a gas results in a decrease in pressure

Answer 29

Molecules become more spread out and so time between collisions increases
This reduces the rate of collisions
Rate of change of momentum increases, and so force exerted on container decreases, resulting in low pressure

Question 30

What can be said about the product of pressure and volume for a fixed mass of gas at a constant temperature?

Answer 30

It is constant
pv = constant

Question 31

What is the unit used for pressure?

Answer 31

Pascal (Pa)

Question 32

What increases when you do work on a gas?

Answer 32

The internal energy of the gas
This can also lead to an increase of temperature

Question 33

Why does the temperature of air inside a bike pump increase when it is pumped?

Answer 33

Work is done on a gas when it is compressed
Doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules
Temperature increases with an increase of average kinetic energy