Particle Model of Matter

Question 2

What is density?

Answer 2

Density is mass per unit volume. It is calculated using: density = mass ÷ volume.

Question 3

What is the unit of density?

Answer 3

Kilograms per cubic metre (kg/m³).

Question 4

What is the formula for density?

Answer 4

Density = Mass ÷ Volume.

Question 5

What is the unit of mass?

Answer 5

Kilograms (kg).

Question 6

What is the unit of volume?

Answer 6

Cubic metres (m³).

Question 7

What is internal energy?

Answer 7

The total energy stored in a system’s particles, including kinetic and potential energy.

Question 8

What increases when you heat a substance?

Answer 8

Its internal energy increases.

Question 9

What are the two types of energy in internal energy?

Answer 9

Kinetic energy (due to motion) and potential energy (due to position).

Question 10

What is specific heat capacity?

Answer 10

The energy needed to raise the temperature of 1 kg of a substance by 1°C.

Question 11

Give the formula for specific heat capacity.

Answer 11

ΔE = m × c × Δθ.

Question 12

What does ΔE represent?

Answer 12

Change in thermal energy (Joules).

Question 13

What does m represent in the specific heat formula?

Answer 13

Mass in kilograms (kg).

Question 14

What does c represent?

Answer 14

Specific heat capacity (J/kg°C).

Question 15

What does Δθ represent?

Answer 15

Temperature change in degrees Celsius (°C).

Question 16

What is specific latent heat?

Answer 16

The energy needed to change the state of 1 kg of a substance without changing its temperature.

Question 17

Formula for energy using latent heat?

Answer 17

Energy = Mass × Specific Latent Heat.

Question 18

What is latent heat of fusion?

Answer 18

Energy needed to change a substance from solid to liquid.

Question 19

What is latent heat of vaporisation?

Answer 19

Energy needed to change a substance from liquid to gas.

Question 20

What happens to temperature during melting or boiling?

Answer 20

It stays constant while energy is used to break bonds.

Question 21

What happens to temperature during freezing or condensing?

Answer 21

It stays constant while energy is released as bonds form.

Question 22

Describe particle movement in a solid.

Answer 22

Particles vibrate around fixed positions and are closely packed in a regular arrangement.

Question 23

Describe particle movement in a liquid.

Answer 23

Particles are close together but can move past each other randomly.

Question 24

Describe particle movement in a gas.

Answer 24

Particles are far apart and move quickly in random directions.

Question 25

Why are gases compressible?

Answer 25

Because there is a lot of empty space between particles.

Question 26

Why do solids have a fixed shape?

Answer 26

Because their particles are in a fixed arrangement.

Question 27

Why do liquids flow?

Answer 27

Because particles can move past each other.

Question 28

What is gas pressure?

Answer 28

The force exerted by gas particles colliding with container walls.

Question 29

What is the effect of increasing temperature on gas pressure?

Answer 29

Pressure increases as particles move faster and collide more often.

Question 30

State Boyle’s Law.

Answer 30

Pressure × Volume = constant (for fixed mass at constant temperature).

Question 31

If gas volume is halved, what happens to pressure?

Answer 31

It doubles, assuming temperature stays the same.

Question 32

How can you reduce gas pressure?

Answer 32

Increase the volume or decrease the temperature.

Question 33

How does heating a gas increase pressure?

Answer 33

Particles gain kinetic energy and collide more frequently with the container walls.

Question 34

How does compression affect gas particles?

Answer 34

They are forced closer together, increasing collision rate and pressure.

Question 35

What happens to internal energy during cooling?

Answer 35

It decreases because particles lose energy.

Question 36

Why is energy conserved during changes of state?

Answer 36

Because total energy is transferred but not lost.

Question 37

Does mass change during a state change?

Answer 37

No, mass stays the same.

Question 38

Does temperature change during a state change?

Answer 38

No, temperature remains constant while energy is used to break or form bonds.

Question 39

What is absolute zero?

Answer 39

The lowest possible temperature where particles have no kinetic energy (0 K or -273°C).

Question 40

What happens to pressure if temperature in Kelvin doubles?

Answer 40

Pressure also doubles, if volume is constant.

Question 41

Why do substances with higher density sink in fluids?

Answer 41

Because they have more mass per unit volume.

Question 42

What causes pressure in a sealed container of gas?

Answer 42

Collisions of gas particles with the container walls.

Question 43

What is the unit of specific latent heat?

Answer 43

Joules per kilogram (J/kg).

Question 44

Why does sweating cool the body?

Answer 44

Energy is transferred away from the body as sweat evaporates, reducing internal energy.