CHAP 10 OXIDATION & REDUCTION Flashcards
what is oxidation ?
- gain of oxidation state
- loss of hydrogen
- gain of oxygen
- loss of electron
what is reduction?
-loss of oxidation state
-gain of hydrogen
-loss of oxygen
-gain of electron
what is a REDOX reaction?
reaction when both reduction & oxidation occur simultaneously ( happens at the same time )
what is an example of REDOX reaction?
displacement reactions of halogens/metals , rusting of iron
what are NOT examples of REDOX reactions?
neutralisation & precipitation
what is an oxidising agent ?
- a substance that brings about oxidation in other substances
- an oxidising agent is itself reduced in the reaction
what can be used to test for a reducing agent?
oxidising agents
what is the colour and example of an oxidising agent?
acidified potassium manganate (VII) KMnO4
( purple) due to MnO4- ion
what is displacement?
occurs when a more reactive element displaces/pushes out a less reactive element from a compound that contains the less reactive element. [ after displacement, less reactive element is now pure & left uncombined.
what are two other methods to test for reducing agents?
1) add iodine solution to the reducing agent
- brown iodine solution turns colourless/ decolourises when reduced
eqn: MnO4- + 8H+ + 5e -> Mn2+ + 4H2O
2) add aqeous iron(III) chloride to the reducing agent
- brown iron(III) chloride turns pale green when reduced
eqn: Fe3+(aq) + e -> Fe2+ (aq)
what is the main way of testing for oxidising agent?
add aqueous potassium iodine into the oxidising agent
observ : colourless aqueous potassium iodine turns brown
eqn: 2I- —> I2 + 2e-
what is an alternative way of testing for oxidising agent?
- add aqueous iron(II) sulfate to the oxidising agent
observ : green aqueous iron (II) sulfate turns brown
eqn: Fe2+(aq) - 1e —> Fe3+
