Extracting Metals: Reduction with Carbon and Choosing a Method
A metal sits in its ore as a compound, and getting it out is a reduction. Where the metal falls in the reactivity series decides whether carbon is a strong enough reducing agent or whether electricity has to do the job, which is why aluminium stayed a precious metal long after iron was common.
What a learner can do afterwards
- Use the reactivity series to predict whether a given metal can be extracted by reduction with carbon
- Write the reduction of a metal oxide by carbon and identify what is oxidised and what is reduced
- Explain why the extraction method for a metal is an economic argument as well as a chemical one
1 · Read
Metals sit in rock locked inside compounds, mostly oxides mixed with useless stone. Unreactive metals barely cling to oxygen. Reactive metals like aluminium grip so hard that ordinary chemical tricks fail. That grip decides the extraction method.
Getting a metal out is always a reduction: the metal ion gains electrons and becomes free metal. Carbon burns happily in oxygen, so it rips oxygen from weaker partners like iron and copper oxides. The carbon is oxidised while the metal is reduced.
Read the method off the reactivity series. Carbon sits between aluminium and zinc. Metals below carbon fall to carbon, and metals above it, aluminium included, need electricity instead.
Electrolysis drags metal ions to an electrode with huge currents, and that power costs money. That is why aluminium stayed precious long after iron tools were common. Choosing a method is a money question too.
Below carbon, carbon reduces the oxide; above carbon, electricity must; and the power bill explains the price.
More to read
18.2 Occurrence and Preparation of the Representative Metals
Metals in rocks sit locked inside compounds, mostly oxides, mixed with useless stone. Mining first digs up this ore, then chemistry pulls the metal free. How hard that pull is depends on how tightly the metal clings to oxygen. Unreactive metals barely cling at all, while reactive ones like aluminium grip so hard that ordinary chemical tricks fail. This grip strength decides the whole extraction method.
17.1 Review of Redox Chemistry
Getting a metal out is always a reduction: the metal ion gains electrons and becomes free metal. Carbon is happy to burn in oxygen, so it rips oxygen away from weaker partners like iron and copper oxides. The carbon is oxidised to carbon monoxide or dioxide while the metal is reduced. Reading any equation like this, spot who gains oxygen and who loses it, and you have named the oxidised and reduced substances.
17.7 Electrolysis
Above carbon in the reactivity series sit metals carbon cannot beat, aluminium included. For those, electricity does the pulling in a process called electrolysis. A huge current flows through the molten ore and drags the metal ions to an electrode where they gain electrons. It works beautifully and it drinks power, which is why aluminium stayed precious long after iron tools were common. Choosing carbon or electricity is a money question as much as a chemistry one.
17.6 Corrosion
Corrosion is extraction running in reverse, with air and water slowly turning iron back into oxide we call rust. It proves the same reactivity rules in everyday life: iron gives up electrons easily, so it rusts, while gold barely reacts at all. Protecting cars and bridges means blocking the oxygen and water or attaching a more reactive metal that corrodes first. The reactivity series predicts rusting just as surely as it predicts smelting.
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2 · Watch
به انگلیسیTake it off screen
Where it sits
Learn first
Optional connections
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.