CORE Chemistry (Short Course) - 9222 OxfordAQA

Redox Reactions

Muhtasari

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.

Malengo

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

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Maelezo ya Somo

Iron does not occur in the ground as iron. It occurs as iron(III) oxide, a red-brown rock in which every iron atom is already locked to oxygen. Getting metal out of it means stripping that oxygen away, and a furnace is essentially a very large, very hot machine built to do exactly that. The furnace wins. Then the beam, the bridge or the gate goes out into damp air, and over the following years the oxygen quietly walks back in. The orange crust that forms is iron(III) oxide again. A whole industry of galvanising, painting, greasing and electroplating exists to slow down a reaction that is simply the reverse of the one the furnace was built to force.

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Tathmini ya Somo

Hongera kwa kukamilisha somo la Redox Reactions. Sasa kwa kuwa umechunguza dhana na mawazo muhimu, ni wakati wa kuweka ujuzi wako kwa mtihani. Sehemu hii inatoa mazoezi mbalimbali maswali yaliyoundwa ili kuimarisha uelewaji wako na kukusaidia kupima ufahamu wako wa nyenzo.

Utakutana na mchanganyiko wa aina mbalimbali za maswali, ikiwemo maswali ya kuchagua jibu sahihi, maswali ya majibu mafupi, na maswali ya insha. Kila swali limebuniwa kwa umakini ili kupima vipengele tofauti vya maarifa yako na ujuzi wa kufikiri kwa makini.

Tumia sehemu hii ya tathmini kama fursa ya kuimarisha uelewa wako wa mada na kubaini maeneo yoyote ambapo unaweza kuhitaji kusoma zaidi. Usikatishwe tamaa na changamoto zozote utakazokutana nazo; badala yake, zitazame kama fursa za kukua na kuboresha.

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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Vitabu Vinavyopendekezwa

OxfordAQA International GCSE Chemistry (9202)

Manukuu: Student Book

Mchapishaji: Oxford University Press

Mwaka: 2016

ISBN: 978-0-19-837589-0

Maelezo: The endorsed student book for the 9202 specification, covering the full subject content with required practicals and exam guidance.

OxfordAQA International GCSE Combined Sciences Chemistry (9204)

Manukuu: Student Book

Mchapishaji: Oxford University Press

Mwaka: 2017

ISBN: 978-0-19-842308-9

Maelezo: The chemistry half of the Combined Science series. A lighter parallel treatment of the same content, useful for a second explanation.

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Ungependa kufanya mazoezi ya maswali ya majaribio kuhusu Redox Reactions? Pakua programu ya Green Bridge CBT ili kupata maswali ya majaribio na tathmini kamili za mazoezi kuhusu mada hii.

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