Melting Point and Freezing Point of

Naphthalene SSI 3013 Information and

Communication Technology in Science

Name: Matric No.:Chan Su Fang D 20101037450Chang Pei Xian D 20101037455Rochelle Tang Nga Ning D 20101037537

Group : ALecturer : En. Azmi Ibrahim

Data Logging• Definition:

Is the measurement and recording of physical or electrical parameters over a period of time.

Components in Data Logger

1. Computer

2. Sensor• Digital sensor

• Analogue sensor

3. Interface

4. Data logging software

Engage, Empower & Enhance• Engage

–Involve the students in the activity

(set induction)

• Empower–Give the students a sense of confidence or

self-esteem in term of education

(construct scientific ideas or concept)

• Enhance–Increase the degree of details for the

concept

(guide students in reflecting their own ideas related to the daily life)

EngageWhat caused the changes in

the state of matter?When a solid is heated

gradually, what will be happened to the particles in the solid?

When a liquid is cooled, what will be happened to the particles in the liquid?

EngageWhen a solid is heated

gradually, what will be happened to the particles in the solid?

When a liquid is cooled, what will be happened to the particles in the liquid?

Engage How to determine the

melting and freezing point of Naphthalene?

Empower

Figure 1: Heating of Naphthalene

Procedure

Figure 1: Heating of Naphthalene

Empower1. The apparatus is set up as shown in Figure 1.

2. The temperature probe (sensor) is connected to the correct port on the interface. The interface is then connected to the computer. The powers to the interface and to the computer are switched on.

3. A computer file is opened to record and display the results as a graph of temperature against time.

Empower5. The program recording conditions is set to:

a) Recording time from 60 ºC until 90 ºC for temperature of naphthalene

6. The naphthalene is placed in a boiling tube to about one third of the depth of the tube.

7. The boiling tube is placed in a beaker under Bunsen burner until all the naphthalene has liquefied.

8. The data is recorded.

EmpowerResult

Table 1: Heating of Naphthalene

Empower

1. What are the states of naphthalene at Point A, from Point B to C, and at Point D?

2. What is the melting point of naphthalene?

3. Why there is an increase from Point A to B and also from Point C to D?

4. Why the temperatures from Point B to C remain constant?

EmpowerDiscussion

1. At Point A, naphthalene exists as solid.From Point B to C, naphthalene exists as solid and liquid.At Point D, naphthalene exists as liquid.

2. The melting point of naphthalene is 80.0 °C.

3. There is an increase from Point A to B and also from Point C to D because when the matter is heated, heat energy is absorbed. The particles gain more energy and vibrate faster.

4. The temperatures from Point B to C remain constant because the heat energy absorbed by the particles was used to overcome the forces between the particles so that the solid can turn into liquid.

Empower

Empower

Procedure

Figure 2: Cooling of Naphthalene

1. The boiling tube is removed from the beaker.

2. The tube is clamped upright using a retort stand.

3. The temperature probe (sensor) is placed in the liquid naphthalene as shown in Figure 2.

4. The program recording conditions is set toa) Recording time- until the temperature falls to

about 60 °C.

Empower

5. Recording time- until the temperature falls to about 60 °C.

6. The data is recorded.7. When the naphthalene has solidified, the

recording is stopped. 8. The boiling tube is removed from the clamp

and placed back into hot water. When the naphthalene has liquefied, the temperature probe is removed and it is rinsed with water.

Empower

EmpowerResult

Table 2: Cooling of Naphthalene

Empower

1. What are the states of naphthalene at Point E, from Point F to G, and at Point H?

2. What is the freezing point of naphthalene?

3. Why there is an increase from Point E to F and also from Point G to H?

4. Why the temperatures from Point F to G remain constant?

EmpowerDiscussion

1. At Point E, naphthalene exists as liquid.From Point F to G, naphthalene exists as liquid and solid.At Point H, naphthalene exists as solid.

2. The freezing point of naphthalene is 80.0 °C.

3. There is an increase from Point E to F and also from Point G to H because when the matter is cooled, heat energy is released. The particles lose their kinetic energy and vibrate slower.

4. The temperatures from Point F to G remain constant because the heat loss to the surroundings is exactly balanced by the heat energy liberated as the particles attract one another to form a solid.

Empower

Due to the unique characteristic of naphthalene, with same melting and freezing points (80 °C), the mothball wouldn’t melt in room temperature.

Enhance

However, the mothball is able to sublime at room temperature by the way its melting point is 80°C. Explain how naphthalene can be melt and sublime.

Enhance

Conclusion Nowadays, the fast growing technology has

influences the direction of learning process especially in science laboratory classes. We as a future Science teacher should be able to implement data logger in laboratory class. The technology that available such as the data logger, makes practical work becomes more efficient as students do not have to spend more time to set up the apparatus and recording the data.