Good Science Victorian Curriculum Year 7

INVESTIGATIONS
Investigation 4.4
Exploring melting points
KEY SKILL
REPRESENTING DATA
When you write a formal investigation report there is
always a results section that includes your data, often as
a table, chart or image. Choosing how to represent your
data so that it can be clearly communicated to someone
reading your investigation report is an important
skill. In this investigation, after you have collected and
recorded your data in the results table, turn your table
into a chart or graph.
Hint #1: There are many ways to visualise your data, such
as bar charts, line graphs and pie charts. Make sure you
choose the best one for your data set.
AIM
To investigate the melting and boiling points of different
household substances
MATERIALS
• household liquids (e.g. water, vinegar, dishwashing
liquid, cooking oil, juice, milk, candle wax, soft drink)
• ice-cube tray (to make ice cubes small enough to fit
inside the test tubes)
• test tubes (one for each substance, large enough to fit
ice cubes)
• thermometer
• large beaker
• Bunsen burner
• heatproof mat
RESULTS
TABLE I1.4
• tripod
• gauze mat
• matches
Sample Melting point Boiling point
OPEN FLAMES, HOT LIQUID, WAX AND STEAM
ARE HAZARDS. TAKE CAUTION. IF YOU BURN
YOURSELF, TELL YOUR TEACHER IMMEDIATELY
AND PLACE THE BURNT AREA UNDER COLD
RUNNING WATER FOR 20 MINUTES.
60 min
Level 2
METHOD
1 The day before the investigation, pour each
substance into a separate ice cube mould. Place the
trays in a freezer overnight.
2 Collect your solid, frozen samples.
3 Copy the results table into your notebook, adding
a title and rows as needed.
4 Set up the Bunsen burner, tripod and gauze mat.
5 Half fill a large beaker with water. This will act as
your water bath for the test tube samples.
6 Remove one of the samples from the ice-cube tray
and place it into a test tube. Place the test tube into
a large beaker. Continue to place test tubes into the
beaker if space permits.
7 Set up the apparatus.
8 Light the Bunsen burner beneath the beaker and heat
the sample until it has completely melted. Use the
thermometer to measure the melting point of the
sample and record in your table.
9 If time permits, continue to heat the sample until
it begins to boil. If you are boiling several samples
together, make sure that there is some space between
the test tubes.
10 Use the thermometer to measure the boiling point
of the sample and record in your table.
11 Repeat steps 6–10 for the rest of your samples.
QUESTIONS
1 Which substances had low melting points?
2 Which substances had high melting points?
3 Which substances had low boiling points?
4 Which substances had high boiling points?
5 Consider the classroom you are currently in.
Can you identify something in the room that would
have a very high melting point? Justify your answer.
CONCLUSION
Copy and complete:
‘The results show that: (respond to the aim)’.
152 GOOD SCIENCE VICTORIAN CURRICULUM 7