Fenton's reagent is used to oxidize potassium hydrogen tartrate, producing carbon dioxide in an exothermic reaction. All of the reagents used in this demo are household ingredients. 

Curriculum Notes 

This demonstration could be used to illustrate a redox reaction, catalysis, or an exothermic reaction. This demo would also be relevant in an environmental chemistry unit when chemical remediation of pollution is being discussed.

One day of lead time is required for this project.

Discussion 

Fenton's reagent is composed of iron(II) ions and hydrogen peroxide. Iron(II) ions act as a catalyst. As hydrogen peroxide oxidizes potassium hydrogen tartrate (cream of tartar), CO₂ is produced in an easily observable exothermic reaction. All of the reagents for this demonstration are obtained from household products. The iron ions are produced by boiling steel wool in vinegar to create a mixture of iron(II) acetate and iron(III) acetate. The acetic acid also makes the solution more acidic, which is required for the optimal performance of Fenton's reagent. The steel wool is first cleaned with nail polish remover containing ethyl acetate to remove grease. The potassium hydrogen tartrate is simply household cream of tartar used in baking, and the hydrogen peroxide is the 3% solution commonly sold in drug stores and grocery stores. Fenton's reagents are frequently used to oxidize contaminants in groundwater. 

Materials 

• iron acetate solution (see prep notes below)
• 150mL 3% hydrogen peroxide
• 3g cream of tartar
• Stir rod
• Temperature probe (optional)

Procedure 

To perform the demonstration, add 150mL of 3% H₂O₂ to a 400mL beaker followed by 3g cream of tartar. Stir the solution with the stir rod and then add 15mL of the iron acetate solution. Stir the solution until bubbles begin to form on the surface, the reaction should proceed with more bubbles forming as CO₂ is evolved. (Optional: monitoring the reaction with a temperature probe shows that the temperature increases markedly as the reaction proceeds.)

Safety Precautions 

Use care when handling the boiling vinegar and hot plate to avoid burns. This demonstration uses household ingredients, so no special precautions need to be taken; however, safety goggles should be worn in all chemical demonstrations, including this one.

Prep. Notes 

Place about 1g of steel wool into a recrystallization dish. Soak the steel wool in nail polish remover for 10 minutes. Remove the steel wool and allow a few minutes to dry. Add the steel wool to a 250mL beaker containing 150mL of vinegar. Boil the vinegar down to 50mL to produce a solution of iron acetate. Allow the solution to cool until it is safe to handle. Then filter the solution into a 250mL Erlenmeyer flask.