P3: Particle model of matter

Question 1

Describe the arrangement and movement of particles in solids.

Answer 1

closely packed

regular

strong forces

particles vibrate in a fixed position

Question 2

Describe the arrangement and movement of particles in liquids.

Answer 2

closely packed

irregular order

particles can slide over each other

Question 3

Describe the arrangement and movement of particles in gases.

Answer 3

weak forces

move in random directions and at random speeds

lots of space between particles

Question 4

What is the formula for density?

Answer 4

Density = mass / volume

ρ = m / V

^{remember that volume is V, not v, which is velocity.}

Question 5

1g/cm³ = ___kg/m³

Answer 5

1000 kg/m³

Question 6

1000kg/m³ = ___g/cm³

Answer 6

1g/cm³

Question 7

How would you find the volume of an irregular object?

Answer 7

• Submerge the object in a eureka can filled with water.
• Position a measuring cylinder next to the can so that the volume of water displaced by the object is transferred to the cylinder.
• Record the volume of water in the cylinder, in ml, and convert this into cm³; this gives you the object’s volume.

Question 8

How would you find the density of an irregular object?

Answer 8

• Measure the object’s mass, using weighing scales.
• Submerge the object in a eureka can filled with water.
• Position a measuring cylinder next to the can so that the volume of water displaced by the object is transferred to the cylinder.
• Record the volume of water in the cylinder, in ml, and convert this into cm³; this gives you the object’s volume.
• Find the object’s density using density = mass/volume.

Question 9

How would you find the density of a liquid?

Answer 9

• Place a measuring cylinder on a weighing scale and zero the balance.
• Add a set volume of liquid (1ml = 1cm³) to the cylinder and measure the mass on the scales.
• Find the density using density = mass/volume.
• You could improve the accuracy by taking repeat readings and calculating an average.

Question 10

What is the word for when a solid becomes a gas?

Answer 10

Sublimation

Question 11

What is the word for when a gas becomes a solid?

Answer 11

Deposition

Question 12

The internal energy of a substance is stored in what two ways?

Answer 12

1. Kinetic energy stored in particles.
2. Potential energy stored in their bonds.

Question 13

What is specific heat capacity?

Answer 13

The amount of energy required to raise the temperature of 1kg of a substance by 1ºC.

Question 14

What is specific latent heat?

Answer 14

The energy required to change the state of a substance, or the energy released when a substance changes state.

Question 15

Specific latent heat, solid ⇌ liquid, = ___

Specific latent heat, liquid ⇌ gas, = ___

Answer 15

1. SLH of fusion
2. SLH of vaporisation

Question 16

Why is the kinetic energy of particles in gases given as an average?

Answer 16

Because particles move at varying speeds. (This is due to collisions.)

Question 17

What causes pressure in containers filled with gases?

Answer 17

Particles move at high speeds so they collide with, and exert a force on, the walls of the container.

Question 18

1. For a gas of a fixed mass at a fixed temperature, what is the relationship between the pressure and the volume of the container?
2. What is the formula that shows this?

Answer 18

1. Pressure and volume are inversely proportional.
2. pV = constant

Question 19

What is the unit and symbol for pressure?

Answer 19

1. Unit = pascals (Pa)
2. Symbol = p

Question 20

Describe what happens to the internal energy of a liquid when it is heated and explain why.

Answer 20

1. When the liquid is heated, the internal energy store of the substance increases.
2. This is because energy is transferred by heating to the kinetic and potential energy stores of the particles.