The Effect of Metal on the Rusting of Iron (Kesan Logam ke atas Pengaratan Besi)

Experiment carried out by 5M students of SMK Khai Mun, 28700 Bentong, Pahang on 13th July 2011.

The picture below shows the set up of the apparatus to study the effect of other metal on the rusting of iron.

A: Iron nail only
B: Iron nail coiled with Magnesium strip
C: Iron nail coiled with copper strip
D: Iron nail coiled with Zinc strip
E: Iron nail coiled with tin strip
All of the nails and metal strips are placed in the same volume of agar+potassium hexacyanoferrate (III) solution + phenolphtalein

And the result shown as below (after 2 days, on 15th July 2011):


We can see the pink and blue colouration that that is formed in the test tubes.

Observation:
A: Low intensity of blue colouration
B: High intensity of pink colouration
C: High intensity of blue colouration
D: Low intensity of pink colouration
E: Low intensity of blue colouration (higher than A, but lower than C)

Explanation:
1. The high and low intensity of blue colouration shows the high and low quantity of iron(II) oxide ions present
2. The high and low intensity of pink colouration shows the high and low quantity of hydroxide ions present.

The function of the substances as below:
1. potassium hexacyanoferrate(III) solution : to detect the presence of Iron(II), Fe2+ ion by the blue colouration
2. Phenolphtalein: to detect the presence of hydroxide ion, OH-
3. Agar/jelly: to make sure the colouration can be seen clearly

Oxidation occurs when iron rust. Oxidation half equation: Fe -> Fe2+ + 2e

And something strange just happen, the Jumping Jelly!