Redox Reactions
Visão Geral
A furnace in Nigeria, Brazil or China spends its whole working life pulling oxygen off iron ore, and the moment the finished steel leaves the mill the air begins putting that oxygen back. Extraction and corrosion look like completely unrelated pieces of chemistry. They are the same process running in opposite directions, and once you can see that, a large part of this course stops being a list of separate reactions and turns into one idea wearing different clothes.
That idea is redox, and this specification gives you a single, very portable test for spotting it: follow the oxygen. A substance that finishes with more oxygen than it started with has been oxidised, one that finishes with less has been reduced, and any reaction where both of those are going on at once is a redox reaction. You will finish this lesson able to take an equation you have never seen before, decide in under a minute which substance was oxidised and which was reduced, and say exactly how you know.
Objetivos
- Oxidation can be described as the gain of oxygen by a substance and reduction as the loss of oxygen from a substance. Students should be able to describe chemical reactions within this specification in terms of oxidation and reduction using the definitions above.
- When oxidation and reduction are happening at the same time this is known as a redox reaction, for example: Fe2O3 + 3 CO 2 Fe + 3 CO2 Oxidation
Mapa mental
Este tema esta mapeado para mostrar como as ideias se ligam.
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Nota de Aula
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Avaliação da Lição
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- Which of these describes oxidation? A. the gain of oxygen by a substance B. the loss of oxygen from a substance C. a rise in the temperature of a substance D. the formation of a precipitate Answer: A
- In the reaction Fe2O3 + 3 CO -> 2 Fe + 3 CO2, which substance is oxidised? A. Fe2O3 B. CO C. Fe D. CO2 Answer: B
- Zinc oxide is heated with carbon: 2 ZnO + C -> 2 Zn + CO2. Which substance is reduced? A. carbon B. zinc C. zinc oxide D. carbon dioxide Answer: C
- Which statement about a redox reaction is correct? A. Oxidation happens first and reduction happens afterwards. B. Only reactions that involve a metal can be redox reactions. C. Oxidation and reduction take place at the same time. D. A substance that is reduced always ends up with a smaller mass. Answer: C
- Carbon dioxide is passed over hot carbon: CO2 + C -> 2 CO. Which statement is correct? A. Carbon is reduced and carbon dioxide is oxidised. B. Carbon is oxidised and carbon dioxide is reduced. C. Neither substance is oxidised or reduced, because both contain carbon. D. Both substances are oxidised. Answer: B
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