6.4 Redox (Cambridge (CIE) O Level Chemistry): Flashcards
Exam code: 5070
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What is a redox reaction?
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What is a redox reaction?
A reaction in which oxidation and reduction take place simultaneously.
In a redox reaction, oxidation involves the ______ of electrons and reduction involves the ______ of electrons.
In a redox reaction, oxidation involves the loss of electrons and reduction involves the gain of electrons.
Remember OIL RIG: Oxidation Is Loss, Reduction Is Gain.
True or False?
In the reaction ZnO + C → Zn + CO, carbon is reduced.
False.
Carbon gains oxygen, so it is oxidised. Zinc oxide loses oxygen, so it is reduced.
An ______ agent oxidises another substance and is itself reduced.
A ______ agent reduces another substance and is itself oxidised.
An oxidising agent oxidises another substance and is itself reduced.
A reducing agent reduces another substance and is itself oxidised.
In the ionic equation Zn (s) + Cu2+ (aq) → Zn2+ (aq) + Cu (s), identify the reducing agent. State precisely which particles are involved and what happens to their electrons.
Zinc atoms are the reducing agent.
They lose electrons and are themselves oxidised:
Zn → Zn2+ + 2e-
Copper ions are the oxidising agent; they gain electrons:
Cu2+ + 2e- → Cu.
When acidified aqueous potassium manganate(VII) is added to a reducing agent, its colour changes from ______ to ______.
When acidified aqueous potassium manganate(VII) is added to a reducing agent, its colour changes from purple to colourless.
What colour change is observed when aqueous potassium iodide is added to an oxidising agent?
The solution turns from colourless to brown, due to the formation of iodine (I2).
The oxidation number of an uncombined element is ______. The oxidation number of a monatomic ion equals its ______.
The oxidation number of an uncombined element is zero. The oxidation number of a monatomic ion equals its charge (e.g. Cu2+ has oxidation number +2).
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