You will need:
- A stove (open flame)
- 4 paper clips (plain steel without the colourful plastic coating)
- A cup of ice cold water
- Plate
- Prongs/Tongs
Understand the science behind the molecular
activity in metals with this experiment.
INSTRUCTIONS
- Take your paper clips and gently open all of them into straight lines. Ask an adult to help you.
- Holding the first paper clip steady with one hand, bend it back and forth at a certain point, a few times.
- Take the second straightened paper clip and ask the adult to hold it with prongs and heat it on an open flame till it burns bright orange.
- Leave the heated paper clip aside on a plate and do not touch it for at least 15 minutes.
- Repeat the heating process with the third paper clip as well. Only when you get it off the stove, dump it straight into a cup of ice cold water till it cools.
- Leave the fourth straightened paper
clip the way it is. - After each paper clip has cooled, try
bending them slightly. - How has the metal changed in each paper clip?
RESULT
The first paper clip is ‘work hardened’, making it stiffer than before. The second paper clip undergoes ‘annealing’ which allows the molecules to move around freely once the metal is heated; bending the metal is easier once it cools. The third paper clip is ‘quenched’, where, as soon as it was put in ice cold water, the molecules cannot rearrange themselves making them hard and brittle. The last paper clip is stiffer than the first and third paper clips since its molecular structure is left untouched.
