Topic 3 Particle Model of Matter

Question 1

density =

Answer 1

mass / volume

Question 2

Define density

Answer 2

how many particles have been packed into a space

Question 3

Describe a solid

Answer 3

Particles vibrate in a fixed position, strong forces, not much energy, close together in a regular position

Question 4

Describe a liquid

Answer 4

Particles are close together and random, move around each other, fairly strong forces, more energy

Question 5

Describe a gas

Answer 5

Particles are far apart and random, move quickly in all directions with a range of speeds, no forces, lots of energy

Question 6

How do you calculate the density of a cube?

Answer 6

• use a ruler to measure the length, depth and height
• times them together to find volume
• weigh the cube using a mass balance
• use density = mass/volume to calculate

Question 7

How do you find the density of an irregularly shaped object?

Answer 7

• measure the mass using a mass balance
• use a displacement can, full to the spout with water and place the object in the can
• use a measuring cylinder to measure the water that has been displaced (the volume of water is equal to the volume of the object)
• use density = mass/volume to calculate

Question 8

Define internal energy

Answer 8

total kinetic and potential energy

Question 9

What is it called when a solid changes to a gas?

Answer 9

sublimation

Question 10

What is it called when a gas changes to a solid?

Answer 10

deposition

Question 11

Define specific latent heat

Answer 11

the amount of energy required to cause a change of state of 1kg of material

Question 12

Define specific heat capacity

Answer 12

the amount of energy needed to raise the temperature of 1kg of material by 1degrees

Question 13

What is the equation involving specific latent heat?

Answer 13

energy = mass X specific latent heat ( e = mL)

Question 14

What does specific latent heat of fusion mean?

Answer 14

the amount of energy required for a solid to turn into a liquid (the freezing/melting point)

Question 15

What does specific latent heat of vaporisation mean?

Answer 15

the amount of energy required for a liquid to turn into a gas (evaporating/condensing point)

Question 16

Why are there flat bits on a heating curve?

Answer 16

energy is being used to pull particles apart and break their bonds instead of movement so temperature doesn’t change - it shows when a change of state occurs

Question 17

Explain why pressure in a gas increases as the gas is compressed

Answer 17

When the gas is compressed, the volume decreases. This means there are more frequent collisions between the particles and the container and each other. Each particle collision causes a force so more frequent collisions causes the forces that get exerted on the walls to get stronger.

Question 18

What is the equation for pressure and volume?

Answer 18

pressure X volume = constant
p1 X V1 = p2 X V2

Question 19

What causes pressure?

Answer 19

air particles move and collide with each other and the container, the more particles means more frequent collisions which increases pressure

Question 20

Describe the experiment to find the density of a liquid

Answer 20

• measure the mass of an empty beaker using a mass balance
• pour 100ml of liquid into the beaker and weigh again
• total mass subtract beaker mass to find mass of liquid
• use density = mass/volume to calculate

Question 21

Is change of state a physical or chemical change?

Answer 21

physical

Question 22

Does mass stay the same when a substance changes state?

Answer 22

Yes