P3 - Particle Model of Matter

Question 1

What is the definition of density ? State the relevant equation with units

Answer 1

• The mass per unit volume of a material
• p=m/v
  -Density (kg/m^3), Mass (kg), Volume (m^3)

Question 2

State the different states of matter in order ( least to most ) of density of atoms.

Answer 2

• Least dense: Gas
• Liquid
• Most dense: solid

Question 3

Describe the particle arrangement of a solid

Answer 3

Tightly packed in a regular arrangement.
Particles can only vibrate on the spot

Question 4

Describe the particle arrangement of a liquid

Answer 4

Close together , but with an irregular arrangement. They can flow over each other

Question 5

Describe the particle arrangement of a gas

Answer 5

Seperated , with no regular arrangement. Particles can move freely.

Question 6

What is always conserved when a substance undergoes a change of state ?

Answer 6

Mass

Question 7

How does a change of state differ from a chemical change ?

Answer 7

In a change of state , the material can return to having its previous properties if the change is reversed.

Question 8

What is sublimation ?

Answer 8

When a solid changes into a gas without passing through a liquid state

Question 9

What is evaporation ?

Answer 9

When a liquid changes into a gas state

Question 10

What is the opposite of evaporation ?

Answer 10

Condensation ,which is when a gas changes into a liquid state

Question 11

When water boils in an open pan , why does the mass of the pan of water appear to decrease ?

Answer 11

Some of the water will evaporate and turn into water vapour . This will leave the pan meaning the mass of the pan will decrease . The mass of the whole system however remains constant

Question 12

Explain the processes involved when a bathroom mirror mists up

Answer 12

• Hot water evaporates to form water vapour
• This water vapour lands on the cooler mirror
• The vapour condenses and returns to liquid state on the mirror’s surface