Changes of state and particle model

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/metres cubed ) mass ( kg) volume ( metres cubed )

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

Separated , 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 original 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 : when a gas turns into liquid state

Question 11

When water boils in an open pan , why does the mass of the pan 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 process 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 mirrors surface