Physics
Lab 2.2 States of Matter
Overview
The purpose of this laboratory class is to demonstrate
the energy changes that occur when a liquid solidifies.
Naphthalene (moth balls) or candle wax can be used for
this experiment.
IMPORTANT
SAFETY NOTICE
Naphthalene vaporizes
relatively easily. Carry out the experiment in a well-ventilated
area – preferably outside. Use candle wax instead of
naphthalene if necessary.
Naphthalene and candle wax
are both flammable.
Experiment
2.2 Cooling Curve for Naphthalene
Equipment
3 or 4 moth-balls (Alternatively: some candle wax)
Thermometer
Small glass or aluminum container
Hot plate
Stopwatch
Graph paper
Procedure
- Place the moth-balls
in the small container and heat until all of the
material has melted.
- Remove the container
from the heating device.
- Place a thermometer
in the molten naphthalene and record the
temperature at regular intervals. (Say every 30
seconds)
- Record the results in
the table below
- Plot a graph of the
change in temperature with time.
Results
– Experiment 2.2
COOLING CURVE FOR
NAPHTHALENE
TIME
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TEMPERATURE
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(minutes)
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(ºC)
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Questions
- Why did the
temperature remain constant during the time that
most of the naphthalene around the thermometer
bulb was solidifying?
- What is the melting
point of naphthalene?
Answers
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