Rusting of steel wool
- home activity.

From our previous lesson we found out that rusting is a reaction that releases heat (exothermic), as shown in the video on the left with the rusting of steel wool. We also found out that the rusting reaction involved iron and oxygen from the air.
The investigation outlined below involves the rusting of iron in a sealed container.

In order to setup the investigation below you will need:
- a tall jar (about 15-20cm tall)
- vinegar
- a bowl
- food dye
- steel wool (fine)
- straw that bends.
- ruler

Step 1 - Tease and stretch the steel wool out so that the surface area exposed to the air is greater. Then place it into a glass.

 

 
Step 2 - Soak the steel wool pad in vinegar for 1 minute.
Step 3 - Drain the vinegar into the sink and squeeze any excess vinegar from the steel wool.

 

 
Step 4 - Stretch out the steel wool once more and place it at the bottom of a tall jar, as shown on the right. Use a straw to keep it in position as the bottle is turned upside down and placed into a bowl.

 
Step 5 - Place two matches at the bottom of the plat on which to rest the jar onto on simply allow the straw to protrude out from the jar. This is so that the water has room to move in and up the jar. Colour the water so that the water level is easier to see.

 

 

 

Step 5 - Measure the height of the water level inside the jar from the bottom of the bowl. Use a ruler.

Let it stand for 24 hours.

1) What do you expect will happen?

2) Write a hypothesis in the "If ..... then ..... because...." format.

Click for the results.

3) Was the hypothesis supported? Explain.

4) State the :
- dependent variable
- independent variable

 

5) Repeat the investigation instead this time record the level of water inside the jar and complete the table below.

Water level inside the jar versus time of rusting
Time of rusting (hrs) Water level (mm)
   
   
   
   

6) Graph the results on an appropriately labeled set of axes
7) Explain why the volume of air inside the jar changed.


8) Air is composed of 21% oxygen gas. Calculate the percentage change of the air inside the jar.
This is done by using the following formula.
=> (Change in the level of water inside the jar / height of the jar) X 100
9) Using your answer above explain what reaction may have taken place and name the reactants and products.
10) Look at the before and after images of the steel wool.
a) Describe what you see.
b) Investigate the properties of the substance formed from the steel wool. How does the new substance differ from the original steel wool. View the video on the right.

Further investigation.

Can the rusted steel wool conduct electricity as well as the unrusted steel wool?
From what you know so far give a reason as to why copper is used in wires instead of iron.