1B 3b Redox pairs flash cards

Flash cards to help you learn the key reactions.

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H⁺(aq), a clear, colourless solution. Is reduced to...	H₂(g) A colourless gas which burns with a 'pop'.
Fe²⁺(aq), a pale green solution. Is oxidised to...	Fe³⁺(aq), a pale orange solution which forms a blood-red complex with thiocyanate.
BrO₃^- (bromate), a clear, colourless solution. Is reduced to...	Br₂(aq). Pure bromine is a red fuming liquid, but in dilute solution it looks orange.
Copper metal is an orange/brown solid. It is oxidised to...	Cu²⁺, a blue solution which forms a royal blue complex with ammonia.
Br₂(aq), an orange solution, is reduced to...	Br^-, a colourless solution.
H⁺/Cr₂O₂^2-, acidified dichromate is orange. It is reduced to...	Cr³⁺, chromium(III), which is blue-green.
H⁺/NO₃^-, concentrated nitric acid, is a clear, colourless solution. It is reduced to...	NO₂(g), nitrogen dioxide, a brown gas with a sharp smell.
H⁺/C₂O₄^2-, acidified oxalic acid (which needs to be heated) is a clear, colourless solution. It is oxidised to...	CO₂, a colourless gas which turns limewater cloudy.
PbO₂, lead dioxide, is a dark brown powder. It is reduced to...	Pb²⁺, a colourless solution (with a white precipitate) which forms a bright yellow precipitate with iodide.
I^-, iodide, is colourless. It is oxidised to ...	I₂, iodine, which forms the orange-brown I₃^- complex in excess I^-, and turns starch solution blue-black.
Blue copper sulfate solution (Cu²⁺) is poured into colourless potassium iodide solution (I^-). Name and describe both oxidation and reduction products.	The I^- is oxidised to I₂, which first turns the iodide orange-brown, and then (as iodide is oxidised) forms a black precipitate. The Cu²⁺ is reduced to Cu⁺ which combines with I^- to form insoluble, white, CuI.
IO₃^-, iodate, is colourless. It is reduced to...	I₂, iodine, which forms the orange-brown I₃^- complex in excess I^-, and turns starch solution blue-black.
H⁺/MnO₄^-, acidified permanganate, is a purple solution. It is reduced to...	Mn²⁺, which is colourless in dilute solution and very pale pink in concentrated solutions.
MnO₄^-, neutral permanganate, is a purple solution. It is reduced to...	MnO₂(s), manganese dioxide, which is brown.
MnO₄^-, permanganate, is a purple solution. In alkaline conditions it is reduced to...	MnO₄^2-, which is a dark green solution.
H₂O₂, hydrogen peroxide, is a colourless liquid. It is oxidised to...	O₂(g), oxygen gas, which is colourless (seen here with brown MnO₂).
S₂O₃^2-, thiosulfate, is a clear, colourless solution. It is oxidised to...	S₄O₆^2-, tetrathionate, which is also clear and colourless. (Note: there is no positive test for this ion.)
Cl^- in concentrated hydrochloric acid, is a clear, colourless liquid. It is oxidised to...	Cl₂(g), a pale green-yellow gas which turns starch-iodide paper blue-black and then bleaches it.
SO₃^2-, sulfite, is colourless. It is oxidised to...	SO₄^2-, sulfate, which is also colourless but forms a white precipitate in acid conditions with barium chloride solution. SO₂ gas and HSO₃^- (hydrogen sulfite, also called bisulfite) are also oxidised to SO₄^2-.
I₂, iodine, in excess iodide, is an orange-brown solution. It is reduced to...	I^-, iodide, which is colourless.