T3 changes of state and particle model

Question 1

definition of density

state the relevant equation with units

Answer 1

• 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 of density of atoms

Answer 2

• least: gas
• liquid
• 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 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
• vapour condenses and returns to liquid state on the mirror’s surface