The table below shows the common and important oxidizing agents:
Oxidizing Agent | Half Equation | Colour change when added to reducing agent | Application |
---|---|---|---|
Acidified potassium manganate (VII)
$\text{KMnO}_{4}$ | $\text{MnO}_{4}^{-} (\text{aq}) + 8 \text{H}^{+} (aq) + 5\text{e}^{-} \rightarrow \text{Mn}^{2+} (\text{aq}) + 4 \text{H}_{2}\text{O}(\text{l})$ | Purple to pale pink (or colourless) | Used to test for reducing agent |
Acidified potassium dichromate(VI)
$\text{K}_{2}\text{Cr}_{2}\text{O}_{7}$ | $\text{Cr}_{2}\text{O}_{7}^{2-} (\text{aq}) + 14\text{H}^{+}(\text{aq}) + 6 \text{e}^{-} \rightarrow 2\text{Cr}^{3+} + 7\text{H}_{2}\text{O}$ | Orange to green | Oxidizes alcohol to acids; used to test for $\text{SO}_{2}$ gas |
Chlorine
$\text{Cl}_{2}$ | $\text{Cl}_{2} (\text{g}) + 2\text{e}^{-} \rightarrow 2\text{Cl}^{-} (\text{g})$ | Greenish yellow to colourless | Oxidizes bromide to bromine and iodide to iodine |
Testing for presence of reducing agent:
- Add an oxidising agent, e.g. Aqueous potassium manganate (VII) to the reducing agent
- Shake the mixture
- The aqueous potassium manganate (VII) is decolourised
The table below shows the common and important reducing agents.
Reducing Agent | Half Equation | Colour change when added to oxidizing agent | Application |
---|---|---|---|
Aqueous potassium iodide
$\text{KI}$ | $2\text{I}^{-} (\text{aq}) \rightarrow \text{I}_{2} (\text{aq}) + 2\text{e}^{-}$ | Colourless to brown | Used to test for oxidizing agent |
Aqueous iron(III) sulphate
$\text{FeSO}_{4}$ | $\text{Fe}^{2+} (\text{aq}) \rightarrow \text{Fe}^{3+} (\text{aq}) + \text{e}^{-}$ | Green to brown | – |
Carbon Monoxide
$\text{CO}$ | – | – | Used to reduce iron oxides to iron in blast furnace |
Hydrogen | $\text{H}_{2} (\text{g}) \rightarrow 2\text{H}^{+} (\text{aq}) + 2\text{e}^{-}$ | – | Reduces copper(II) oxide to copper |
Metals
E.g. $\text{Mg}$, $\text{Na}$ | – | – | Displacement of less reactive metals |
Testing for presence of oxidising agent:
- Add a reducing agent, e.g. Aqueous potassium iodide to the oxidising agent.
- Shake the mixture.
- A brown solution of iodine is produced.
- The presence of iodine can be confirmed by adding starch solution.
- A dark blue coloration is obtained.
You guys should also use ammonium sulphate and pottasium dicromate