EOY The Particle Model Level 2

Question 1

Why do solids expand when they are heated

Answer 1

As the particles vibrate more, they are pushed further apart.
Volume increases

Question 1

Are changes of state physical or chemical changes and why?

Answer 1

Physical changes because they are reversible

Question 2

Give a real-life example of problems from solid expansion

Answer 2

Metal railway tracks can buckle if they expand on a hot day.
Expansion gaps are left to prevent this.

Question 3

Why is a gas the only state of matter that can be compressed?

Answer 3

Gas is the only state of matter with space between the particles.
When gases are compressed, this space decreases.

Question 4

What’s the difference between evaporation and boiling?

Answer 4

Evaporation occurs at the surface, at all temperatures.

Boiling only occurs at boiling point and occurs throughout the liquid

Question 5

Internal energy = kinetic energy + potential energy.

What change is apparent in a substance when a kinetic energy changes?

Answer 5

When kinetic energy increases, the temperature of the substance increases.

Temperature = average kinetic energy of the particles.

Question 6

What change is apparent when potential energy changes?

Answer 6

When potential energy changes, the state of the substance changes.

Question 7

What are the relative potential energies of the different states?

Answer 7

Gas: highest potential energy

Liquid: lower potential energy

Solid: lowest potential energy

Question 8

Why does a heated substance not increase in temperature when it is melting or boiling?

Answer 8

Because the energy is being used to weaken or break the bonds and change the state, not make the particles’ kinetic energies increase.

Question 9

Why is it beneficial to make cooking pans from a metal with a low specific heat capacity?

Answer 9

Because a low shc means that a material heats up with relatively low energy supplied.