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Example 1

Example 1. Potassium iodide is added to a solution of potassium permanganate which has been acidified with sulfuric acid. I - → I 2. MnO 4 - → Mn 2+. Observation: When the purple solution (MnO 4 - ) is added to the colourless solution (I - ), a brown solution is formed (I 2 ). .

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Example 1

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  1. Example 1 Potassium iodide is added to a solution of potassium permanganate which has been acidified with sulfuric acid. I- → I2 MnO4- → Mn2+ Observation: When the purple solution (MnO4-) is added to the colourless solution (I-), a brown solution is formed (I2).

  2. Example 1 Potassium iodide is added to a solution of potassium permanganate which has been acidified with sulfuric acid. 2I- → I2 + 2e- MnO4- + 8H++ 5e-→ Mn2++ 4H2O 2MnO4- + 16H++ 10I-→ 2Mn2++ 8H2O + 5I2 I- is the reductant because it has lost electrons to react to I2. MnO4- is the oxidant because the oxidation number of Mn changed from +7 to +2.

  3. Example 2 Sulfur dioxide gas is bubbled through a solution of iron(III) chloride. SO2→ SO42- Fe3+ → Fe2+ Observation: When the colourless gas (SO2) is bubbled through the orange solution (Fe3+), a pale green solution is formed (Fe2+).

  4. Example 2 Sulfur dioxide gas is bubbled through a solution of iron(III) chloride. SO2+ 2H2O→ SO42- +4H+ + 2e- Fe3+ + e- → Fe2+ SO2+ 2H2O+ 2Fe3+→ SO42-+ 4H+ + 2Fe2+ Fe3+ is the oxidant because it has gained electrons to react to Fe2+. SO2 is the reductant because the oxidation number of S changed from +4 to +6.

  5. Example 3 Sulfur dioxide gas is bubbled through a solution of acidified potassium dichromate. SO2→ SO42- Cr2O72- → Cr3+ Observation: When the colourless gas (SO2) is bubbled through the orange solution (Cr2O72-), a green/blue solution is formed (Cr3+).

  6. Example 3 Sulfur dioxide gas is bubbled through a solution of acidified potassium dichromate. SO2+ 2H2O→ SO42- +4H+ + 2e- Cr2O72- + 14H++6e- → 2Cr3++ 7H2O 3SO2+ 2H+ + Cr2O72-→ 3SO42-+ 2Cr3++ H2O Cr2O72- is the oxidant because it has gained electrons to react to Cr3+. SO2 is the reductant because the oxidation number of S changed from +4 to +6.

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