Topic 3- Particle Model Of Matter

Question 1

What is the definition and unit of density?

Answer 1

Mass per unit volume of a material (m/v)

Question 2

Describe particle arrangement in a solid

Answer 2

Tightly packed in regular arrangement- only vibrate on spot

Question 3

Describe particle arrangement in liquid

Answer 3

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

Question 4

Describe the particle arrangement in a gas

Answer 4

Separated- no regular arrangement. Particles move freely

Question 5

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

Answer 5

Mass

Question 6

How does change of state differ from chemical change?

Answer 6

Change of state- can return to previous properties if 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

Explain process when bathroom mirror steams up

Answer 8

Hot water evaporates to form water vapour

Water vapour lands on cool mirror and condenses, returning to liquid state

Question 9

What is the internal energy of a substance?

Answer 9

Energy stored by the particles

Sum of kinetic and potential energies that make up a system

Question 10

How does heating affect energy of a substance

Answer 10

Transfers energy to substance

Increases energy of particles of substance

Question 11

What 2 things can heating a substance do?

Answer 11

1. Raise temp

2. Change its state

Question 12

What 3 factors determine temperature change in a system?

Answer 12

1. Mass of substance
2. Type of material
3. Energy inputted

Question 13

Define specific heat capacity

Answer 13

Amount of energy needed to increase 1Kg of a substance by 1ºC

Question 14

How do internal energy and temp of a substance change when a state change occurs?

Answer 14

Internal energy- increased or decreased

Temp- remain constant

Question 15

Define specific latent heat

Answer 15

Amount of energy needed to change the state of 1Kg of a substance without a change in temperature

Question 16

What is the specific latent heat of fusion?

Answer 16

Energy required to change 1Kg of a substance from solid to liquid without temperature change

Question 17

What is specific latent heat of vaporisation?

Answer 17

Energy required to change 1Kg of a substance from liquid to gas without temperature change

Question 18

Describe motion of molecules in gas

Answer 18

In a constant random motion

Question 19

What factor affects average kinetic energy of gas molecules?

Answer 19

Higher temperature, higher average kinetic energy of molecules

Question 20

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

Answer 20

More collisions per second in high pressure gas than low pressure

Question 21

Explain how increasing volume of a gas decreases pressure

Answer 21

Molecules spread out- time between collisions is shorter.
Reduces rate of collisions
Rate of change of momentum decreases- force exerted on container decreases- lower pressure

Question 22

What is the unit for pressure

Answer 22

Pa (pascal)

Question 23

What increases when you do work on a gas?

Answer 23

Internal energy of gas

Can lead to ncrease of temperate