2.4
EXPERIMENT
Aim
To grow crystals
What affects
crystal size
and determine what
affects their size.
Method
Materials
1Prepare a solution of alum by mixing 2/2
tablespoons of alum with 2 cup of hot
water. Stir until the alum is dissolved.
Alum solution
Bunsen burner
2
Pour roughly equal amounts of alum
solution into the evaporating dish and the
Matches
Heatproof mat
Results
two Petri dishes.
3
Put
Tripod
one
2 Petri dishes
4
5
Put the other Petri dish on
Place the evaporating dish
a
1
window sill.
on
the
gauze mat.
Safety glasses
While wearing safety glasses, gently heat
the
evaporating dish containing the alum
solution over a yellow (safety) flame. The
yellow flame is cooler and will allow for
Tablespoon
7
gentle boiling.
Continue heating
all the water has
8
the solution until
nearly
evaporated.
Observe the size of the
After 2
days, compare
crystals
formed in
the size of the
crystals formed in the two Petri dishes.
10 Observe the
crystals formed
in the
refrigerator again after 4 or 5 days.
162
What was the dependent variable?
Name three variables you needed to
control.
4
Each of these crystals grew over a different
time span. How does the time allowed for
the crystal to form affect the size of the
crystals?
the evaporating dish.
9
What was the independent variable for this
experiment?
2
3
Evaporating dish
250 mL beaker
dishes.
Discussion
of the Petri dishes in the
refrigerator.
Gauze mat
Draw a labelled diagram of the crystals
formed in the evaporating dish and in the two
Petri dishes. Your diagram needs to show the
different sizes of the crystals in the different
OXFORD SCIENCE 8 WESTERN AUSTRALIAN CURRICUL IM
Conclusion
What do you know about the
crystal size?
factors affecting
2.4
EXPERIMENT
Aim
To grow crystals
and determine what
affects their size.
What affects crystal size?
Method
Results
1
Prepare a solution of alum by mixing 2/2
tablespoons of alum with 2 cup of hnot
water. Stir until the alum is dissolved.
Draw a labelled diagram of the crystals
formed in the evaporating dish and in the two
2
Pour roughly equal amounts of alum
solution into the evaporating dish and the
two Petri dishes.
Materials
Alum solution
Bunsen burner
Matches
Heatproof mat
3
Put
one
Gauze mnat
4
Put the other Petri dish
2 Petri dishes
5
Place the
6
While wearing safety glasses,
gently heat
the evaporating dish containing the alum
250 mL beaker
Tablespoon
8
9
the
Name three variables you needed to
control.
4Each of these crystals grew over a different
crystals?
the solution until
all the water has
evaporated.
nearly
the crystal to form affect the size of the
Conclusion
Observe the size of the crystals formed in
What do you know about the
the evaporating dish.
crystal size?
After 2 days, compare the size of the
8
What was the dependent variable?
gentle boiling.
Continue heating
refrigerator again after 4 or 5 days.
SCIENCE
2
time span. How does the time allowed for
crystals formed in the two Petri dishes.
OXFORD
What was the independernt variable for this
experiment?
solution over a yellow (safety) flame. The
yellow flame is cooler and will allow for
10 Observe the crystals formed in the
162
1
window sill.
on
gauze mat.
Evaporating dish
Safety glasses
evaporating
on a
dish
dishes.
Discussion
of the Petri dishes in the
refrigerator.
Tripod
Petri dishes. Your diagram needs to show the
different sizes of the crystals in the different
WESTERN AUSTRALIAN CURRICULUM
fact
affecting