P6: Molecules and Matter

Question 1

Definition of density?

Answer 1

The mass per unit of a material

Question 2

How to calculate density?

Answer 2

Density = mass/volume

Question 3

State the different states of matter?

Answer 3

Gas
Liquid solid

Question 4

Describe the particle arrangement of a solid?

Answer 4

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

Question 5

Describe th particle arrangement of a liquid?

Answer 5

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

Question 6

Describe the particle arrangement of a gas?

Answer 6

Seperated, with no regular arrangemnt. Particles can move freely

Question 7

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

Answer 7

Mass

Question 8

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

Answer 8

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

Question 9

What is sublimation?

Answer 9

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

Question 10

What is evaporation?

Answer 10

When a liquid changes into a gas state

Question 11

What is the opposite of evaporation?

Answer 11

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

Question 12

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

Answer 12

Some of the water 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 13

Explain the processes involved when a bathroom mirror mists up?

Answer 13

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

Question 14

What is the internal energy of a substance?

Answer 14

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

Question 15

How does heating affect the energy of a substance?

Answer 15

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

Question 16

What 2 things can heating a substance do?

Answer 16

Raise its temperature
Change the state of the substance

Question 17

What theee factors determine the temperature change of a system?

Answer 17

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

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?

Answer 20

Energy to change state = mass x specific latent heat

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 of vaporisation?

Answer 22

The energy required to change 1kg of a substance from liquid state to gas state without a chanege 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 temperatue of the substsnce
The higher the temperature, the higher average kinetic energy of the molecules

Question 25

What effect does increasing temperature have on the pressure of a gas when held st constsnt 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 between molecules becomes more frequent Greater rate of change of momentum Greater force and therefore pressure

Question 27

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

Answer 27

Thd net force acts at right-angles to the containers surface The force increases as pressure increases

Question 28

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

Answer 28

It is constant p V = constant

Question 29

What is the unit for pressure?

Answer 29

Pascal (Pa)

Question 30

What increases when you do work on a gas?

Answer 30

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

Question 31

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

Answer 31

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