Page 99 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

Corrosion of Metals
Iron is a metal used extensively in our daily life. Do the articles
made of iron undergo any change over a period of time?

Is it only for the purpose of beautification, that we paint the iron
bars of windows in our houses?
What would happen if we do not do so?

Do you know the factors which favour the rusting of iron?
Shall we do a project?

Materials Required
Fig. 7.7
Clean and dry test tube - 4 Nos.
Rust-free and clean iron nails - 4 Nos.

Quick lime - 10 g
Sodium chloride solution - 25 mL
Dilute hydrochloric acid/Vinegar - 25 mL

Cork - 1 No.
Procedure

Put the iron nails, one each, in the four test tubes (Figure 7.8).
Drop a small piece of moist cotton in the first test tube and keep
it exposed to atmospheric air.
In the second test tube, put some quick lime and keep it closed
(Quick lime can absorb moisture).
In the third test tube, pour some sodium chloride solution such
that half of the nail stays immersed in it.

Fig. 7.8
98 Basic Science VIII