PREPARED BY

NAME ID NUMBER

NORHAFIZAH BINTI NORDIN D20101037456

NURSYAHIRA AYUNI BINTI AHMAD ZAMRI

D20101037457

AIN NABILA BINTI ABD. MALEK D20101037463

TITLE:THE EFFECT OF SALT ON THE RATE OF

CORROSION

ENGAGE

• These two nails were located at same place.

• Nail A was immersed in salt water while nail B was

immersed in plain water.

• Which nails will more corrosive?

Nail A Nail B

Questions

From the situation, what

happen to both nails?

Which nail is more

corrosive? Why?

Can you explain?

EMPOWER

Figure 1: Design of the experiment

Computer

Nail A

Salt water

Test tube

Stopper with

delivery tube

Retort stand

Plan of the experiment

Objective

• To investigate the effect of salt on the rate of corrosion.

Hypothesis

• Salt water increase the rate of corrosion

Variables

• Manipulated variable: Type of water

• Responding variable: The rate of corrosion

• Fixed variable: Temperature

Plan of the experiment

Apparatus

• Nails

• Salt water

• Plain water

• A delivery tube

• Cork

• Pressure sensor

• Retort stand

Plan of the experimentMethods

1. Prepare 2 test tubes labeled A and B.

2. Set up the apparatus as shown in Figure 1.

3. Place a nail in each test tube.

4. Pour salt water in test tube A and plain water in the test

tube B.

5. The water is pored until it overflow from the test tube.

6. Insert the stopper with delivery tube.

7. Make sure there is no air bubble in the test tube.

8. Connect the pressure sensor at delivery tube.

9. The pressure sensor is connected at computer.

10. Measure the pressure change of both test tube over 7

days.

Plan of the experiment

Result

0

0.5

1

1.5

2

2.5

0 2 4 6 8

Pre

ssu

re (

Pa)

Days

The rate of corrosion

salt water

plain water

Plan of the experimentDiscussion

• Based on the result, nail A that immersed in salt water ismore corrosive than nail B that immersed in plain water.

• This is because, oxygen present in water and salt causescorrosion. Salt is hygroscopic in nature and it attracts thewater. Water is required for corrosion and salt speeds upthe process.

• The salt speeds up the corrosion by improves thecapability of water to carry electron through redoxreactions.

• Rusting in metals undergoes an electrochemical process inwhich iron loses electrons by oxidation causing the waterto break into hydroxide ions and oxygen. The metal thathas oxidized reacts with the hydroxide ions and oxygen toform metal oxide. These salts remain even if the water isgone and they again start rusting whenever they come incontact with moisture.

Plan of the experiment

Conclusion

• The salt water increase the rate of corrosion compare

with plain water.

ENHANCE

• From the above pictures, predict the condition of gate

after 10 years based on the locations?

• Give the reasons to support your predictions.

• Explain the changes process.

A- House at Pantai Teluk Lipat B-House at Putrajaya

EXTENSION

• According to the pictures, ship A is more corrosive than

ship B.

• How to reduce the ship A from keep corrosive? Explain.

• Does humidity also affect the corrosion process? If

yes, give the explanation.

Ship A Ship B