BY ZAINAB BINTI ARIFFIN 90286
•Chemical products should be designed so that at
the end of their function they do not persist in the
environment and breakdown into innocuous
degradation product.
•It is better to prevent waste than treat or clean up
waste after it is formed.
•Substances used in a chemicals process should be
chosen as to minimize the potential chemicals
accidents.
•Study the effects of heating and cooling of
the pure substance.
•Construct heating and cooling curve of
pure substance using experimental data.
•Determine the freezing and melting point
of pure substance.
200 ml
water
Naphthalene
BOILING TUBE-FILLED
WITH NAPHTHALENE.
250ML BEAKER-FILLED
WITH 200 ML WATER.
BUNSEN BURNER
NAPHTHALENE
RETORT STAND
TRIPOD STAND
BOILING TUBE HOLDER
THERMOMETER
WIRE
GAUZE
SPATULA
WIRE GAUZE
WIRE
GAUZE
1)Fill one third of the
boiling tube with
Naphthalene.
2)Place the boiling tube
in a beaker of water
standing on a gauze
and tripod stand over
a Bunsen Burner.
3)Heat the water. As the
water is heated ,stir
the naphthalene.
4) Read and record the
temperature every one
minute.
5)Repeat steps 3 and 4
until the temperature
reaches about 90°C.
6)At every stage,observe
and record the state of
naphthalene.
7)Take the boiling tube of liquefied
naphthalene out of the hot water
and allow it to cool slowly.
8)Read and record the temperature
at the interval of one minute till it
reaches about 70ºC.
9)At every stage, observe the state
of the naphthalene.
10)Using the data, draw graphs:

»The temperature against time for
the heating curve of naphthalene.
»The temperature against time for
cooling curve of naphthalene.
Process
Temperature
(°C)
Heating
Around 90.0
Cooling
Around 70.0
State
Solid
become
liquid
Liquid
become
solid
1)Describe the change in temperature at the
initial stage of heating naphthalene
•The temperature increase sharply.
Explain.
•When the solid is heated, heat energy is
absorbed. This causes the particles to
gain kinetic energy and vibrate faster.
This is why the increased in temperature
is observed.
2)When naphthalene is cooled, describe
what happens to:
1.The temperature?
• The temperature decrease.
2.The state of the naphthalene?
• The liquefied naphthalene be in solid
state again.