Topic 3 - Particle Model Of Matter

Question 1

Describe a solid.

Answer 1

Strong forces of attraction.
Fixed, regular arrangement.
Highest density.

Question 2

Describe a liquid.

Answer 2

Weaker forces of attraction.
Can move past each other in irregular arrangements.
Move in random directions at low speeds.
Less dense than solids.

Question 3

Describe a gas.

Answer 3

No forces of attraction.
More energy, so free to move in random directions at high speeds.
Less dense than liquids.

Question 4

How do you find the density of an irregular solid object?

Answer 4

Use a eureka can. Drop the irregular solid in the water and let it flow out into a measuring cylinder and record the volume. Use the formula to find the density.

Question 5

How do you find the density of a liquid?

Answer 5

Put a measuring cylinder on a balance and 0 it. Add 10ml of water and record the mass. Repeat this until it is full. For each measurement find the density. The average of all these is the value of the density.

Question 6

What is internal energy?

Answer 6

Energy stored by the particles that make up a system.

Question 7

What energy stores is internal energy stored in?

Answer 7

Kinetic and potential.

Question 8

How does heating increase the internal energy?

Answer 8

The particles vibrate faster, increasing energy in the kinetic store.

Question 9

What does heating the system lead to?

Answer 9

Change in temperature or state. The change depends on the mass, specific heat capacity and energy input into the substance.

Question 10

Does a change of state conserve mass? Why?

Answer 10

Yes. A change of state is a physical change. Therefore the number of particles doesn’t change between states - they’re just in different arrangements. This means mass is conserved.

Question 11

Why doesn’t temperature increase or decrease at a certain point in temp/time charts, despite the substance still being heated or cooled?

Answer 11

The internal energy is still increasing or decreasing, but the energy is used for breaking or forming the bonds rather than a heat change. This is known as latent heat.

Question 12

What is specific latent heat?

Answer 12

The amount of energy needed to change 1kg of a substance to another state without a change in temperature.

Question 13

What is the specific latent heat of fusion?

Answer 13

SLH for melting or freezing.

Question 14

What is the specific latent heat of vaporisation?

Answer 14

SLH between a liquid and gas.

Question 15

What happens as you increase the temperature of a gas?

Answer 15

The average speed of its particles increases because of the formula for kinetic energy.

Question 16

How do gases exert pressure?

Answer 16

As they collide with things it exerts a force. In a sealed container, the total force exerted by the particles on a unit area is the gas pressure.

Question 17

Does gas pressure increase or decrease as particle speed increases?

Answer 17

Increases.

Question 18

If temperature is constant and volume is increased, what happens to the gas pressure?

Answer 18

It decreases.

Question 19

What does the pressure of the gas cause? (A net…

Answer 19

A net outwards force at right angles to the surface of the container.

Question 20

What is the equation for density?

Answer 20

Density = mass / volume
Density is rho measured in kg/cm3
Mass is kg
Volume is cm3

Question 21

Give the equation showing pressure and volume are inversely proportional.

Answer 21

Pv = constant

Question 22

How does doing work on a gas increase the temperature?

Answer 22

Doing work increases the internal energy, causing energy to be transferred to the kinetic energy store and making the temperature rise.