Redox Reaction Between Potassium Permanganate (KMnO₄) & Sucrose (C₁₂H₂₂O₁₁)
1. TITLE : Chameleon redox 2. AIM: The aim of the experiment is to test the reaction that occurs between table sugar(sucrose) and potassium permanganate(KMnO₄). 3. HYPOTHESIS: It is predicted that when sucrose is combined with potassium permanganate, the potassium permanganate will change colour as a result of oxidation and reduction or redox for short. 4. RISK ASSESSMENT: Hazard and associated harm Risk Precautions to be taken Sodium hydroxide and potassium permanganate can cause irritation when in contact with skin or mucous membranes. Low Wear appropriate safety gear such as gloves, safety goggles and lab coats when handling the chemicals.
5. METHOD: 5.1a. Materials ● 0.2mg of potassium permanganate(KMnO₄) ● 300ml of distilled water ● 10g of sodium Hydroxide(NaOH) ● 15g of sucrose (table sugar) 5.2a Apparatus ● 1 250ml conical flasks ● 1 500ml beaker ● 2 50ml measuring cylinders 5b. Steps I. Start preparing the first solution by combining 50mg of potassium permanganate to 200 ml of distilled water into the conical flask. Mix well to make sure the potassium permanganate is fully dissolved. This will be our first solution or for the sake of simplicity, Solution A. II. For the second solution, add 100 ml of distilled water to the beaker followed by 10g of sodium hydroxide and 15g of sugar and mix well. The reaction between sodium hydroxide and water is exothermic so some heat will be produced. This will be Solution B. III. Once both solutions have been prepared, slowly add Solution A into Solution B
and swirl them together to ensure both solutions are thoroughly combined. IV. The reaction shown between both solutions will be instantaneous and have been recorded. 5c. Diagram
6. Results Observations of the reduction of potassium permanganate when sucrose is oxidised. Stage Initial state Initial colour Reaction Current state Current colour 1 Permanganate ion Purple Reduced Manganate ion Green 2 Manganate ion Green Reduced Manganese dioxide Golden brown 7. Discussion The colour changes are the result of oxidation and reduction or a redox reaction. The potassium permanganate is reduced (gains electrons), while the sugar is oxidised (loses electrons). This occurs in two steps. First, the permanganate ion (purple in solution) is reduced to form the manganate ion (green in solution): ● MnO4- + e- → MnO42- As the reaction is proceeding, both the purple permanganate and green manganate are present, blending together to produce a solution that appears blue. Eventually, there is more green manganate, yielding a green solution. Next, the green manganate ion is further reduced and forms manganese dioxide:
● MnO42- + 2 H2O + 2 e- → MnO2 + 4 OHManganese dioxide is golden brown solid, but the particles are so small they make the solution appear to change colour. Eventually, the particles will settle out of solution, leaving it clear. 8. Conclusion The aim of the experiment has been achieved and it was found due to the oxidation of sucrose that the reduction of potassium permanganate is able to occur. Further investigation shows the potassium permanganate solution continues to reduce until it becomes a completely clear solution. These results support the initially proposed hypothesis.