Topic 3 - Particle model of matter

Question 1

What is the equation that links density, mass and volume ?

Answer 1

density (kg/m^3) = mass(kg) / volume (m^3)

Question 2

Describe the particle arrangement in solids.

Answer 2

Stong forces of attraction between particles
fixed , regular arrangement
vibrate in fixed positions

Question 3

Describe the particle arrangement in liquids.

Answer 3

weaker forces of attraction
close together
irregular arrangements
move in random directions at low speeds

Question 4

Describe the particle arrangement in a liquid.

Answer 4

almost no forces of attraction between particles
free to move in all directions at high speeds

Question 5

Describe a method to find out the density of an irregular solid object.

Answer 5

1) use a balance to measure the object’s mass
2) fill a eureka can with water
3) place the object in the eureka can andcollect the displaced water in a measuring cylinder
4) thevolume of displaced water is the volume of the object
5) use the mass and volume to work out density uing density = mass/ volume

Question 6

Describe a method to find out the density of a liquid.

Answer 6

1) place a measuring cylinder on a balance and zero the balance
2) pour 10ml of the liquid into the measuring cylinder and record the liquid mass
3) pour another 10ml into the measuring cylinder, repeating the process untill the cylinder is full and recording the total volume and mass each time
4) for each measurement , use the formula to find the density
5) finally, take an average of your calculated densities

Question 7

What is internal energy ?

Answer 7

The total energy that its particles have in their kinetic and potential energy stores.

Question 8

What happens to the particles in a substance when it is heated up ?

Answer 8

heating them transfers energy to its particles kinetic store (makes them move faster ) , increasing the internal energy .
this leads to a change in temperature or change in state.

Question 9

name the five changes of state.

Answer 9

freezing - liquid to solid
melting- solid to liquid
boiling - liquid to gas
condensing- gas to liquid
sublimating - solid to gas

Question 10

Why are there flat parts on a graph with temperature against time when heating a substance?

Answer 10

when heating a substance, you are increasing its energy store by putting energy in.
when it is melting or boiling, the energy is used for breaking bonds rather than raising the temperature .

Question 11

why are there flat parts on a graph with temperature against time when cooling a substance?

Answer 11

when a substance is condensing or freezing ,, bonds are forming between particles , which releases energy.
this means the internal energy decreases but the temperature doesnt go down .

Question 12

What is latent heat?

Answer 12

the energy needed to change the state of a substance .

Question 13

What is specific latent heat?

Answer 13

the amount of energy needed to change 1kg of a subsatnce from one state to another without changing its temperature

Question 14

What is specific latent heat of fusion?

Answer 14

the specific latent heat for changing between a solid and a liquid

Question 15

what is specific latent heat of vaporisation?

Answer 15

specific latent heat for changing between a liquid and a gas

Question 16

What is the equation for specific latent heat?

Answer 16

energy= mass x specific latent heat

Question 17

explain how a gas in a sealed container exerts pressure on the walls of the container .

Answer 17

The particles move at high speeds colliding with eachother and the walls of the container .
When they collide they exert a force.
Faster particles and more frequent collisions both lead to an increase in net force and so gas pressure.

Question 18

what is the relationship between pressure and volume?

Answer 18

Pressure and volume are inversely proportional

Question 19

Explain how a change in pressure can cause a change in volume.

Answer 19

The pressure of a gas causes a net outwards force at right angles to the surface area of its containter.
there is also a force on the outside of the container due to the pressure of the gas around it.
uf a container can easily change its size, then any change in these pressures will cause the container to compress or expand due to the overall forces.

Question 20

Explain why using a bike pump may cause the tires to get warmer.

Answer 20

the gas applies pressure to the plunger of the pump and so exerts a force on it.
work has to be done agaisnt this force to push down the plunger,
this transfers energy to the kinetic energy stores of the gas particles, increasing the temperature.
if the pump is connected to a tyre , you should feel it getting warmer.