MadSci Network: Edible/Inedible Experiments Archive

Splitting the Smartie

Area of Science: Chemistry
Meant for at least Grade K-3 (age 5-7).
This experiment is edible.
An adult need not be present.

See ink magically split up into different colours

1. Filter paper or blotting paper
2. Tube of smarties
3. Small cup of water
4. Plate

keep the experiment on the plate until it dries or you might stain the table cloth

How to do the experiment:
1. Cut the blotting paper into circles about 15cm across.
2. Place the plate on a flat surface and the paper on the plate.
3. Place a smartie in the center of the paper.
4. Dip your finger into the water and hold it above the smartie allowing a little water to rip onto the sweet.
5. Repeat fairly slowly until the sweet is quite wet and the circle of water on the blotting paper is about 5 cm across.
6. Leave.
7. In a little while you should be able to see rings of colour round the smartie.

You may now eat the smartie. Explanation:
The colour in the sugar coating of the smartie shell disolves in the water. The water is drawn out through the paper by capillary action and moves in a growing circle. The different inks which make up the smartie colour move at different speeds and so they are separated.

At the 'molecular level' smaller hydrophilic molecules migrate faster through the paper. Hydrophilic means a "water-loving" substance, as opposed to hydrophobic compounds wich are not soluble in water. Cooking oil is an example of a hydrophic substance. The colors that migrate the furthest from the candy have less of a mass than the ones closest to the candy.

Note that once the shell is wet, the smartie is not so crispy!

Useful References:

Further comments:
Repeat with different colours - which colour smarties are made of the most different inks?

I think m&m's work quite well, and you can also make a felt tip blob in the middle of the paper and look at felt tip inks. However, felt tips cannot be eaten afterwards.

Experiment submitted on Tue Jul 29 09:05:39 1997 by:
Name: robin hall
Institution: UWSwansea
Position: undergrad (chemistry)

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