3. Particle Model of Matter

Question 1

Define Density

Answer 1

Density is defined as the mass per unit volume

Question 2

Density Formula

Answer 2

Question 3

Describe in your own words:

Answer 3

Notes:
- All particles in these states contain kinetic energy
- By heating an object, we increase the kinetic energy of the particles

Question 4

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

Answer 4

Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed

Question 5

What is always conserved when a substance changes state?

Answer 5

When a substance changes state, mass is always conserved

Question 6

Why does the mass stay the same when a substance changes state?

Answer 6

When a substance changes state, the number of particles in the substance does not change

Question 7

What are the 6 changes of state?

Answer 7

Question 8

What is internal energy?

Answer 8

Internal energy is the energy is stored inside a system by the particles that make up the system

Question 9

What is internal energy made up of?

Answer 9

Internal energy is made up of the total kinetic energy and potential energy of all the particles that make up the system

Question 10

What effect does heating have on the energy of a substance?

Answer 10

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

Question 11

What are the 2 results of heating a substance?

Answer 11

Heating a substance:
- Raises its temperature
OR
- Changes the state of the substance

Question 12

What three factors determine the temperature change of a substance?

Answer 12

• Mass of substance being heated
• Type of substance
• Energy inputted into substance

Question 13

What is latent heat?

Answer 13

Latent heat is the energy needed for a substance to change state

Question 14

What happens to the internal energy and temperature of a substance when a change of state occurs?

Answer 14

When a change of state occurs:
- The internal energy of the substance will change however the temperature of the substance will remain constant

Question 15

Why does the temperature not change when a substance is changing state?

Answer 15

The temperature does not change as a substance changes state as the internal energy that is being transferred is being used to overcome the forces of attraction between particles, allowing the substance to change from solid to liquid or liquid to gas

Question 16

Define Specific Latent Heat

Answer 16

Specific Latent Heat is the amount of energy required to change the state of one kilogram of a substance without a change in temperature

Question 17

Specific Latent Heat formula

Answer 17

Question 18

Heating graph

Answer 18

Question 19

What is specific latent heat of fusion?

Answer 19

The change of state from solid to liquid

Question 20

What is specific latent heat of vaporisation?

Answer 20

Change of state from liquid to vapour

Question 21

Describe the motion of molecules in a gas

Answer 21

The molecules of a gas are in constant random motion

Question 22

What factor affects the average kinetic energy of gas molecules?

Answer 22

The temperature of the gas affects the average kinetic energy of gas molecules as:
- the higher the temperature, the higher the average kinetic energy of the molecules