Topic 3 - Particle Model of Matter

Question 1

What is the equation for

density?

Answer 1

density = mass/volume

p = m/v

p: kg/m3 or g/cm3
m: kg or g
v: m3 or cm3

Question 2

Describe:

• forces of attraction
• arrangement
• energy
• and density

in a solid.

Answer 2

• strong forces of attraction
• fixed, regular arrangement
• the particles don’t have much energy so they only vibrate about their fixed positions
• generally highest density in this state as the particles are closest together

Question 3

Describe:

• forces of attraction
• arrangement
• energy
• and density

in a liquid.

Answer 3

• weaker forces of attraction between the particles
• the particles are close together, but can move past each other, and form irregular arrangements
• more energy than the particles in a solid - they move in random directions at low speeds
• generally less dense than solids

Question 4

Describe:

• forces of attraction
• arrangement
• energy
• and density

in a gas.

Answer 4

• almost no forces of attraction
• 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

Question 5

How would you find the

density of a liquid?

(5 steps)

Answer 5

1. Place a measuring cylinder on a mass balance and zero it.
2. Pour 10ml of the liquid into the measuring cylinder and record the liquid’s mass.
3. Pour another 10ml into the measuring cylinder, repeating the process until 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. This will give you a value for the density of the liquid.

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

What is the change of state from

solid to gas?

Answer 7

sublimation

Question 8

Define

specific latent heat.

Answer 8

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

solid -> liquid is specific latent heat of fusion
liquid -> gas is specific latent heat of vaporisation

Question 9

What equation links

specific latent heat, energy and mass?

Answer 9

energy needed to change state = mass x specific latent heat

E = mL

E: joules, J
m: kg
L: J/kg

Question 10

What is the relationship between pressure and volume for a gas of fixed mass and constant temperature?

Answer 10

pressure and volume are inversely proportional