Resources: The handout, paper, pens and books/internet for research.
Core Handout: Extracting metals information sheet, questions regarding extracting methods and challenge task questions.
If necessary, revise KS2 content such as the properties of metals and corrosion.
Where do metals come from? Using the slide as a prompt, the students should discuss how metals are obtained.
Using the presentation slides, give a brief introduction into the history of metal extraction, which leads on to the discovery of carbon being used to extract metals from metal oxides. Introduce students to the term smelting and explain the purpose of a blast furnace in extracting iron from iron oxide. In this reaction, the iron oxide loses oxygen as so this is a reduction reaction (opposite of oxidation). Explain that where a metal is found in the reactivity series indicates how it can be extracted (e.g. metals above carbon are extracted by electrolysis and outline this process).
As the students watch a video of an old metal extraction technique - thermite reaction - ask them to discuss what they see happening. Aluminium powder and iron oxide are mixed together and put in a pot. A magnesium fuse is then added. Initially, they will see the fuse burning down, which provides the energy for the reaction. Then, as the reaction starts, they will see a large amount of energy being produced (exothermic), and molten iron dripping into the sand tray.
Ask the students: what type of reaction is this? Why does this happen? This links back to the last lesson where displacement reactions were covered; aluminium is more reactive than iron and so will displace it from its compound.
Students either use the information in the handout or their own research to produce a summary of methods for extracting the metals iron, aluminium and copper. Then, to ensure understanding, complete the core task in handout. There is also a challenge task where students can consider why we should be recycling metals and practise balancing equations.
Career Film: Take a tour around Rolls Royce SMR's Heritage Museum in Derby to find out about Chloe Magee's job. Chloe works as an Indirect Buyer for Rolls Royce SMR.
Expert Film: This is Mark Salisbury. Mark works as the Group Head of Regulatory Affairs for Rolls Royce SMR. Listen to Mark as he explains how metals can be extracted from ores.
Metal Extraction
Students should present a summary of metal extraction. This can be presented as written prose, poster or leaflet. They should include iron extraction in the blast furnace, copper extraction from malachite ore and aluminium extraction through electrolysis.
They can either research the ideas for themselves or for support use the information on the handout.
Support: Ask the students to use the information on the handout to help produce a summary about the extraction of iron, copper and aluminium from their ore, completing the table template.
Challenge: Students explain why metals should be recycled and practise balancing chemical equations for extraction methods.
Discuss challenge task regarding recycling metals, as this will be a good introduction for later in this unit.
Metals are arranged in a reactivity series. This basically means that a list exists to show the most reactive metal to the least reactive metal in a series of reactivity. There are a bunch of metals that lie in between. Unreactive metals find it more difficult to partake in a chemical reaction whereas reactive metals find it a lot easier. The general reactivity series is as follows: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, tin, lead, copper, silver, gold and platinum. Potassium is the most reactive and platinum is the least reactive. Potassium tends to react vigorously with water. Gold will not because it is super unreactive. Carbon fits in depending on its reactivity with metal oxides. It usually comes under aluminium.
Different extraction methods exist to extract metals from metal oxides. This will depend on the position of the metal in the reactivity series. Electrolysis is used to extract metals from their compounds. A lot of energy is required to undergo this process, so it isn’t usually a favoured method.
Metals that are less reactive than carbon can be extracted from their oxide by heating it with the non-metal, carbon. Carbon is used to displace the metal from its compound. This will remove the oxygen from the oxide and as a result, leave the metal. So, for zinc, iron, copper, silver and gold, heating with carbon is the favoured extraction method. Let’s explore an example. Zinc oxide reacts with carbon to release zinc and carbon monoxide as products. The balanced equation is as follows: ZnO + C -> Zn +CO. As you can see from the reaction, oxygen is lost which means that it is reduced.
The carbon essentially takes the oxygen from the zinc. It gains the oxygen and as a result, becomes oxidised. Carbon is said to displace the metal from its oxide. This is how carbon is used to obtain the metals from their oxides. You can apply this example to all of the other metals that come under carbon in the reactivity series.