Describing the changes of states of matter for naphthalene and the cooling curve and heating curve also shown with information of the curves.

1. NAPHTHALENE
XYLENE AR

2. WHAT IS NAPHTHALENE?
Solid white flake
Melting and freezing point at 800C
Mothballs and toilet deodorizer among products contains naphthalene
Made from coal tar or crude oil
When things burn, also produce naphthalene, such as cigarette
smoke, car exhaust and smoke from forest fires
Half life of naphthalene: less than 1 day (air); > 80 days in soil

3. EXPERIMENT OF HEATING AND COOLING NAPHTHALENE
Precaution: naphthalene in the boiling tube
should be heated using water bath for uniform
heating.
Precaution : 1) the boiling tube must be put in
the conical flask immediately after the heating;
2) Stir the molten naphthalene constantly 
to avoid supercooling.
Molten naphthalene
Conical flask
Thermometer
Boiling tube
Naphthalene
Water

4. Temperature (0C)
Time (min)
The heating curve of naphthalene
# Kinetic theory of matter
1) State of matter
2) Arrangement of particles
3) Movement of particles
4) Force of attraction
5) Kinetic energy of particles

5. Temperature (0C)
Time (min)
Melting point
A
D
C
B
1) Solid
1) Solid + liquid
1) Liquid
3) Rotate and vibrate at fixed position
3) Movement: faster
2) Closely packed but not orderly
arrangement
5) Kinetic energy
5) Kinetic energy remains constant
5) Kinetic energy
4) Force of attraction-very strong
4) Force of attraction: weaker
4) Force of attraction-moderate
6) Heat energy absorb  to overcome the force of attraction
between particles
# kinetic theory of matter
2) Closely packed
3) Rotate,vibrate,moving around
2) Arrangement: increase in distance between
particles
The heating curve of naphthalene
Comparison
of point B to C

6. Temperature (0C)
Time (min)
Freezing point
A
D
C
B 1) Solid
1) Liquid +solid
1) Liquid
2) Closely packed
3) Movement : slower
2) Closely packed but not orderly arrangement
5) Kinetic energy
5) Kinetic energy remains constant
5) Kinetic energy
4) Force of attraction-very strong
4) Force of attraction- stronger
4) Force of attraction-moderate
6) Heat energy released to form bond between particles
# Kinetik theory of matter
3) Rotate, vibrate, moving around
2) Arrangement: decrease in distance between
particles
3) Rotate and vibrate
The cooling curve of naphthalene
Comparison
of point B to C

7. EXERCISE :
1. Diagram below shows the cooling curve of liquid Z. Which statement can be deduced from the diagram.
70
t 1
0
t 2 t 3
Time (min)
Temperature
(0C)
A. At t1, Z exists as a solid.
B. The freezing point of Z is 700C.
C. From t1 to t2 , Z does not release heat energy.
D. From t2 to t3, the particles are less closely packed.
Answer : B

8. EXERCISE :
2. Solid T is heated in a boiling tube and the temperature is recorded at regular time intervals. If the melting
point of T is 780C, which graph represents the heating curve of T?
78
Time (s)
Temperature (0C)
Answer : B
78
Time (s)
Temperature (0C)
78
Time (s)
Temperature (0C)
78
Time (s)
Temperature (0C)
D
B
C
A

9. EXERCISE :
3. Diagram shows the inter-conversion of the three states of matter, P, Q and R of water.
P Q R
a) What type of particles is found in water?
b) What is the physical state labelled R?
c) Name the process when water changes from state Q to
R.
d) When water changes from state Q to R, state the changes in:
i) The energy of the particles
ii) The forces of attraction between the
particles
Molecule
Gas
Boiling / evaporation
Increase
Weaker