Objective: The students will use different chemical compounds to determine the best catalyst for the production of carbon dioxide from the reaction of hydrogen peroxide and potassium hydrogen tartrate (cream of tartar).

Information

Iron act as a catalyst but the iron has to be in the ionic state. Solid stable iron is not adequate.. 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 ferrous acetate and ferric 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.

Materials

  • iron acetate solution (clean steel wool with acetone(fingernail polish) and then heat 15 ml/per group of vinegar and soak steel wool in it for 15 minutes to create iron acetate solution)
  • 150mL 3% hydrogen peroxide
  • 3g cream of tartar
  • Acetone
  • Steel wool
  • vinegar
  • Stir rod
  • Temperature probe/thermometer

Prerequisite Laboratory Skills: basic lab skills

Procedure

  1. To perform the experiment, add 50mL of 3% H2O2to 3 200mL beakers followed by 1g cream of tartar in each one. Stir and take the temperature of each beaker.
  2. Add a small amount of cleaned steel wool to the first beaker. Stir and monitor the temperature-taking temperature readings every two minutes.
  3. Add 5 ml of vinegar to beaker #2. Stir and monitor the temperature-taking temperature readings every two minutes.
  4. Add 5 mL of the iron acetate solution to beaker #3. Stir the solution until bubbles begin to form on the surface, the reaction should proceed with more bubbles forming as CO2 is evolved. Be cautious as the beaker becomes very hot. Take temperature readings every 2 minutes.
  5. Continue taking temperature readings for the three beakers and record the temperatures for 20 minutes. You should had 10 temperature readings per beaker.

Data Using the graph paper supplied by your teacher-graph the temperature vs time lines for all three beakers. Note the difference in Beakers 1 & 2 compared to Beaker 3.

Conclusion: iron in the form of steel wool is iron metal and not in the form of a free flowing ion. When soaked in vinegar, iron reacts with the acetate and forms the ionic compound iron acetate (both ferrous and ferric acetate are formed). This iron ion is able to be a catalyst for the reaction of hydrogen peroxide and cream of tartar. Without the iron ionic particles, the reaction doesn’t take place.

Data Table.

Time / Beaker 1-Temperature / Beaker 2- Temperature / Beaker 3- Temperature
2 min
4 min
6 min
8 min
10 min
12 min
14 min
16 min
18 min
20 min

Extensions:

Use different time, temperature and agitation when making the iron ions to try to create smaller iron ions that would give greater surface area for the catalyst reaction to occur. Vary the formation of iron acetate by making it very slowly by soaking it overnight, agitating it as it reacts, and boiling the solution. If possible, use an electron scanning microscope to determine the size of the catalyst formed.