P1- Particle model of Matter

Question 1

What is density?

Answer 1

A measure of the compactness of a substance. It relates the mass of a substance to how much space it takes up.

Question 2

Formula for density

Answer 2

ρ = m/v
Density = mass/volume
kg/m^3 = kg/m^3

Question 3

How are the particles arranged in solids?

Answer 3

Strong forces of attraction hold the particles together in a fixed, regular, arrangement. The particles dont have much energy so they can only vibrate about their fixed positions. The density is generally highest in this state as the particles are closest together.

Question 4

How are the particles arranged in liquids?

Answer 4

There are weaker forces of attraction between 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. Liquids are generally less dense than solids.

Question 5

How are the particles arranged in gases?

Answer 5

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 travel in random directions at high speeds. Gases are generally less dense than liquids and they have low densities.

Question 6

What is the internal energy of a system?

Answer 6

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

Question 7

When does a change of state occur (internal energy)?

Answer 7

If the substance is heated enough the particles will have enough energy in their kinetic energy stores to break the bonds holding them together.

Question 8

What is the name of the process in which a solid becomes a gas?

Answer 8

Sublimating

Question 9

What is the name of the process in which a gas becomes a liquid?

Answer 9

Condensing

Question 10

Is a change of state physical or chemical?
Explain?

Answer 10

Physical, you do not end up with a new substance as it is the same substance in a different form.

Question 11

What is the energy needed to change the state of a substance called?

Answer 11

Latent heat

Question 12

What is the specific latent heat of a substance?

Answer 12

The energy needed to change the 1 kg of it from one state to another without changing its temperature.

Question 13

During cooling, specific latent heat is….

Answer 13

the energy releases by a change in state

Question 14

The specific latent heat for melting and freezing is called….

Answer 14

the specific latent heat of fusion

Question 15

The specific latent heat for evaporating, boiling or condensing is called….

Answer 15

the specific latent heat of vaporisation

Question 16

Formula for specific latent heat (energy needed or released when a substance of mass changes state)

Answer 16

E = mL
Energy = Mass x SLH
J = kg x J/kg