What are the reactants for the displacement reaction seen in the video?

This appears to be a simple question with a simple answer – iron (Fe) and copper sulfate CuSO₄.

However, we have Fe atoms and Cu²⁺ ions. We also have SO₄^2– ions. The Fe atoms are in solid form while the Cu²⁺ ions are described as aqueous as the copper sulfate is in the form of a solution.

We might represent the reactants as follows:

Fe(s) + Cu²⁺(aq) + SO₄^2–(aq)

What are the products of the displacement reaction?

Copper metal and iron(II) sulfate. This could be represented as:

Fe²⁺(aq) + Cu(s) + SO₄^2–(aq)

The symbolic representation also indicates the physical state of the chemicals involved. There is no mention of water as it is acting as the solvent and is not produced in the reaction. However it's worth remembering that some students may consider that water is involved in the reaction and may predict different products as a result.

This can now be combined with the answer to the previous question to form a full chemical equation.

How might the way we have represented the reactants and products help students understand what might be occurring on the surface of the iron wool?

The key learning point here is that by representing the reactants and products as shown, students could be encouraged to realise that at a microscopic level there needs to be an exchange between iron and copper. In order for this to happen contact between the two species needs to be made.

This is the basis of collision theory, which is essential for the development of a conceptual understanding of rates of chemical reactions.

This is clearly a concept that touches on many aspects of chemistry and more information on this type of reaction can be found by subscribing to the Redox course.

What might be the logical steps in my teaching that I could use to aid understanding of what is happening in a chemical reaction?

1. Reactants are converted into products (this is more clearly grasped if students understand the particle model) Sub-mIcroscopic
2. Reactants collide → bonds break → atoms rearrange → new bonds form → products are created Sub-microscopic and macroscopic
3. No atoms are lost or made (mass is conserved) Macroscopic
4. The change can be summarised in an equation Symbolic representation