21. Changes Of State

Question 1

Describe the arrangement and motion of particles in solid

Answer 1

• close packed regular structure
• fixed pattern, strong forces of attraction between molecules
• high density
• vibrate around fixed position

Question 2

Describe arrangement and movement of particles in a liquid

Answer 2

• close packed, irregular structure
• not fixed, but still strong forces of attraction, so flow over each other
• high density
• move at random

Question 3

Describe motion and arrangement of gas particles

Answer 3

• very spread out
• no fixed position, very weak forces of attraction
• low density
• move with rapid random motion
• expands to fill space

Question 4

What happens to particles in material when it is heated?

Answer 4

• increases its thermal store
• particles increase in kinetic energy, move faster

Question 5

How to obtain a temp time graph to show constant temp during change of state

Answer 5

• cool stearic acid
  1. Record initial temp
  2. Record temp every 30 secs using stop clock
  3. Continue until stearic acid reaches 45c
  4. Plot graph of temp against time