P3

Question 1

State the equation to find the density of a material

Answer 1

Density(kg/m^3) = Mass(kg) / Volume(m^3)
ρ = m/V

Question 2

What is the particle model used to explain

Answer 2

• The different states of matter
• Differences in density

Question 3

Note:

Answer 3

AQA says that students should be able to recognise/draw simple diagrams to model the difference between solids,liquids and gases

Question 4

What is the particle theory?

Answer 4

• In particle theory, you can think of the particles that make up matter as tiny balls
• You can explain the ways that matter behaves in terms of how these tiny balls move, and the forces between them
• The three states of matter are solid (e.g. ice), liquid (e.g. water) and gas (e.g. water vapour)
• The particles of a substance in each state are the same - only the arrangement and energy of the particles are different

Question 5

How are solids arranged?

Answer 5

• Strong forces of attraction hold the particles close together in a fixed, regular arrangement
• The particles don’t have much energy so they can only vibrate about their fixed positions.

Question 6

How are liquids arranged?

Answer 6

• There are weaker forces of attraction between the particles.
• The particles are close together, but can move past each other, and form irregular arrangements.
• They have more energy than the particles in a solid - they move in random directions at low speeds

Question 7

How are gases arranged?

Answer 7

• There are almost no forces of attraction between the particles
• The particles have more energy than in liquids and solids - they’re free to move, and are constantly moving with random directions and speeds

Question 8

Practical 17

Answer 8

AAAA

Question 9

What happens when substances change state?

Answer 9

Mass is conserved

Question 10

Why are physical changes different to chemical changes?

Answer 10

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

Question 11

What is internal energy?

Answer 11

Energy is stored inside a system by the particles (atoms and molecules that make up the system)this is called internal energy

Question 12

What is internal energy?

Answer 12

Internal energy is the total kinetic energy and potential energy of all the particles, (atoms and molecules) that make up a system

Question 13

What does heating do to an object?

Answer 13

• Heating the system transfers energy to its particles (they gain energy in their kinetic stores and move faster), increasing the internal energy
• This either raises the temperature of a system produces a change of state

Question 14

What happens if the temperature of a system increases?

Answer 14

The increase in temperature depends on the mass of a substance, heated the type of material and the energy input into the system

Question 15

How do you find change in thermal energy?

Answer 15

Change in thermal energy(J) = Mass(kg) x Specific heat capacity(C) x Temperature change(C)

△E = mc△θ

Question 16

What is latent heat?

Answer 16

The energy needed for a substance to change

Question 17

What happens when a change of state occurs?

Answer 17

• The energy needed for a substance to change that is called latent heat
• When a change of state occurs,the energy supplied changes the energy stored (internal energy) but not the temperature

Question 18

What is the specific latent heat of a substance?

Answer 18

The specific latent heat (SLH) of a substance is the amount of energy needed to change 1 kg of it from one state to another without changing its temperature

Question 19

How do you find energy for a change of state?

Answer 19

Energy for a change of state(J) = Mass(kg) x Specific latent heat(J/kg)

Question 20

Note:

Answer 20

Check CHP Page 194 and memorise the heating and cooling graphs that include the change of state

Question 21

What is specific heat capacity?

Answer 21

The specific heat capacity of a material is the energy required to raise one kilogram (kg) of the material by one degree Celsius (°C).

Question 22

How are molecules in a gas moving

Answer 22

They are moving at a constant random motion

Question 23

What is the temperature of a gas related to?

Answer 23

The kinetic energy of the molecules

Question 24

What happens if you change the temperature of a gas held at a constant volume?

Answer 24

It changes the pressure exerted by the gas

Question 25

How the motion of the molecules in a gas are related to both its temperature and pressure

Answer 25

1) If you increase the temperature of a gas, you transfer energy into the kinetic energy stores of its particles (there’s more about this on p.193).
2) The temperature of a gas is related to the average energy in the kinetic energy stores of the particles in the gas. The higher the temperature, the higher the average energy.
3) So as you increase the temperature of a gas, the average speed of its particles increases.
This is because the energy in the particles’ kinetic energy stores is ½m? - p.168.
4) This means that, for a gas at a constant volume, increasing its temperature increases its pressure.