Class practical

This experiment shows the position of iron in the reactivity series, by heating iron metal with the oxides of two other metals, copper and magnesium. In each experiment, students look for signs of reaction.

Lesson organisation

This activity can be done as a class practical, and should take about 20 - 30 mins.

Apparatus Chemicals

Eye protection

Each working group requires:

Test-tubes (Note 1)

Bunsen burner

Heat resistant mat

Test-tube holder

Spatula

Iron filings, 2 spatula measures

Magnesium oxide, 1 spatula measure

Copper(II) oxide (HARMFUL, DANGEROUS FOR THE ENVIRONMENT), 1 spatula measure

Refer to Health & Safety and Technical notes section below for additional information.

Health & Safety and Technical notes

Read our standard health & safety guidance

Wear eye protection.

Iron filings, Fe(s) - see CLEAPSS Hazcard.

Magnesium oxide, MgO(s) - see CLEAPSS Hazcard.

Copper(II) oxide, CuO(s), (HARMFUL, DANGEROUS FOR THE ENVIRONMENT) - see CLEAPSS Hazcard.

1 It is not possible fully to clean the test-tubes from Experiment 3. Perhaps a box of ‘used test-tubes’ should be kept for this experiment.

Procedure

a Light a Bunsen burner

b Mix together one small spatula measure of iron filings and an equal measure of copper(II) oxide in a test-tube. Move the tube from side to side to mix the solids.

c Hold the tube in a test-tube holder. Heat the tube strongly with a roaring Bunsen flame. Look for signs of a reaction. Look for a glow that persists well after the tube has been taken out of the flame, and look for any colour change in the tube.

d Repeat the experiment using a mixture of iron filings and magnesium oxide.

e Record, for each experiment:

  • the appearance of the mixture at the start;
  • the appearance of the mixture during heating; and 
  • the appearance of the mixture after heating.

Teaching notes

Students should see a glow in the iron/copper oxide tube and red-brown copper forms. In the iron/magnesium oxide tube, there is no glow and the mixture should look the same (grey and white particles) at the end.

Thus, iron is above copper but below magnesium in the reactivity series.

The reaction that occurs is:

Iron + copper oxide → copper + iron oxide

Copper oxide is reduced to copper by the iron. (Reduction is removal of oxygen, at this level)

Lead oxides are also reduced but should not be used as they give toxic vapours.

Zinc oxide can be used as another unreactive oxide but the fact that it turns yellow on heating (but then back to white on cooling) may confuse students.

Student questions
Here are some possible questions for your students.

In which tube does a reaction occur?

What signs of reaction are there?

What can you conclude about the positions of magnesium, iron and copper in the reactivity series?

Write word equations for any reactions that occur.

In these reactions, what is being reduced?

Health & Safety checked, August 2016

Credits

This Practical Chemistry resource was developed by the Nuffield Foundation and the Royal Society of Chemistry.

© Nuffield Foundation and the Royal Society of Chemistry

Page last updated October 2015