P1 Particle Model

Question 1

What happens to a system as energy is added?

Answer 1

Temperature increases

Question 2

What happens when energy is added at the melting or boiling point?

Answer 2

State changes, not temperature

Question 3

Define a change of state

Answer 3

• physical change
• alters internal energy
• doesn’t change temperature or mass
• not a chemical change

Question 4

Define specific latent heat

Answer 4

the energy needed for 1kg of a substance to change state

Question 5

What is the latent heat of fusion?

Answer 5

energy needed for a substance to turn from solid to liquid

Question 6

What is latent heat of vaporisation?

Answer 6

energy need for a substance to change from liquid to gas

Question 7

How are state changes represented on a graph?

Answer 7

horizontal lines

Question 8

Describe particles in a gas

Answer 8

• constant random motion

- temperature related to kinetic energy of particles

Question 9

Explain how pressure is exerted on a gas

Answer 9

Particles of gas collide with the walls of their container and exert force on the wall, felt as pressure

Question 10

Assuming volume is kept constant, what is the effect of increasing temperature?

Answer 10

• particle speed increases
• increases frequency and force of which particles hit the walls
• increases pressure

Question 11

Assuming temperature is constant, explain the effect of changing volume of gas in a container

Answer 11

• increasing size reduces pressure, particles collide with wall less frequently
• reducing volume increases pressure as particles collide more frequently

Question 12

for a fixed mass of gas at constant temperature…

Answer 12

p1V1 = p2V2

Question 13

What happens when work is done on a gas?

Answer 13

Increases internal energy so causes an increase in temperature

Question 14

Explain what happens when a bicycle pump is compressed

Answer 14

• piston hits the gas particles; gives them more energy
• temperature increases
• as the are moving faster, particles collide with objects more frequently so pressure increases

Question 15

Describe the density required practical

Answer 15

For a regularly shaped object…

• Measure each side with a ruler
• Multiply together for volume
• Weigh for mass

For an irregularly shaped object…

• Fill Eureka can with water and measure
• Place object fully underwater
• Measure water displace for volume
• Weigh for mass

For a liquid…

• Fill measuring cup with water
• Add liquid being measure
• New height - original height = volume

Question 16

What should be considered during the density required practical?
(low density, taking readings, temperature)

Answer 16

• If a solid is less dense than water, the volume will be incorrect as the solid won’t be fully submerged
• When reading from a cylinder, the reading should be taken from the bottom of the meniscus
• Water temperature should be same throughout as a change could alter volume through expansion