Tartarate Ion and Hydrogen Peroxide Reaction
- Description: A mixture of tartarate ion and hydrogen peroxide does not react, even at 70°C. Adding cobalt ions as a catalyst causes the reaction to proceed; the color of the mixture changes from pink to green, accompanied by considerable foam.
- Source: Fun with Chemistry: A Guidebook of K-12 Activities; M. and J. Sarquis Volume: 2 Page: 253
Catalytic Decomposition of Hydrogen Peroxide
Catalyst Used
- Fe(III) is used as a catalyst to decompose hydrogen peroxide (H₂O₂).
- The catalytic role is evident as the color of the catalyst remains unchanged.
- MnO₂ can also be used effectively.
Purpose
To illustrate that catalysts speed up a reaction and are themselves not consumed in the process.
Materials Needed
- MnO₂ powder
- 50 mL H₂O
- Dish soap
- 50 mL of 30% H₂O₂
- 1L graduated cylinder
- Iron nitrate solution (freshly prepared)
Procedure
- Preparation: See Chem Educator for preparation of solutions.
- Set Up: In a 1L graduated cylinder, add a spatula full of MnO₂.
- Add Liquid: Pour a mixture of 50 mL H₂O and dish soap on top of the MnO₂.
- Add H₂O₂: Carefully pour about 50 mL of 30% H₂O₂ on top.
- Safety Precautions: Wear gloves and emphasize the instability of concentrated H₂O₂. Write the decomposition reaction on the board.
Demonstration Steps
- Show students a bottle of hydrogen peroxide and discuss its common uses, highlighting the difference between the 3% in medicine cabinets and the 30% solution.
- Pour some H₂O₂ into a beaker and place it under a document camera. Ask how they would know if it is degrading (bubbles indicate breakdown).
- Prompt students to think about how to make it bubble more vigorously, guiding them to the idea of cuts and blood.
- Explain that blood contains catalase, a catalyst that decomposes H₂O₂, and that the iron III ion in catalase is essential for this reaction.
- Show the iron solution (rust-colored) and add it to the graduated cylinder with MnO₂ and H₂O₂.
- Stand back and observe the reaction: it will turn black, bubble, then produce a significant amount of foam and steam.
Follow-Up Discussion
- Discuss how to determine the production of oxygen (using a match to test for it).
- Reinforce the concept of catalysis by noting that the color of the catalyst remains unchanged, and further hydrogen peroxide can be added for additional reactions.
- Caution against using large amounts of hydrogen peroxide after the initial run due to the heat generated during the reaction.