Elephant Toothpaste Lab

This is a guideline to help you write up a formal lab report. This is not to be used as the formals lab report. You do not have to turn this in.

Purpose: To break down a compound and release the maximum amount of substance in an elemental form.

Background: (Sample) Hydrogen peroxide is an extremely reactive substance with the symbol H2O2 (water is H2O). That extra oxygen atom makes hydrogen peroxide a powerful oxidizer and it is widely used in strong concentrations as an industrial bleaching agent. It is corrosive to human skin in concentrations above 8% but very useful as an antiseptic at lower concentrations such as 3%.

Hydrogen peroxide readily decomposes into water (H2O) and oxygen gas (O2) in the presence of even trace amounts of a proper catalyst. Catalysts are chemicals that increase the rate of a reaction. It this case, the catalyst is being used to increase the rate of breakdown of H2O2. Just a few grams of the catalyst potassium iodide (KI) causes nearly all of the hydrogen peroxide in a 30% solution to rapidly decompose. Significant quantities of heat and oxygen gas are released during decomposition making this an exothermic (heat releasing) reaction that should be handled with care. A squirt of detergent lowers the solutions surface tension so that the oxygen produced forms tiny bubbles which combine to make a very large volume of foam.

Add something about the strength of catalysts. You will need to look this up before coming to class.

Question: Which catalyst concentration will supply the most oxygen, 2M or saturated potassium iodide solution?

Hypothesis: I hypothesize ______because ______.

Materials:

• 20 ml Hydrogen peroxide (30%) - This is ten times stronger than the normal hydrogen peroxide you can find at the store • 5ml potassium iodide solution, 2 M and saturated potassium iodide • 5ml Liquid soap (a small squirt will do) • 5 drops Liquid Food coloring running down the side of the graduated cylinder • Erlenmeyer flask about 250ml or graduated cylinder 200- 500ml in size • Lighter • Splints • timers • Safety glasses • Rubber gloves for clean-up

Methods

1. Measure 20 mL of the 30% hydrogen peroxide into the Erlenmeyer flask or cylinder. It's best to place the cylinder in a large tray to make the clean-up as easy as possible. 2. Add a squirt (that's a technical term meaning about 5 mL) of dish soap to the graduated cylinder containing the 30% hydrogen peroxide. 3. Add a few drops (approximately 5 drops) of food coloring run down the sides of the cylinder to spice things up. 4. Add 5 mL of the 2M sodium iodide solution (2M refers to the molarity which is a concentration of the solution). The reaction takes place quickly, so it's important to stand back. 5. Determine how you will measure how much oxygen is present. Write it here. ( Hint - How can you detect whether or not you generated oxygen gas with this reaction?)

6. Use all possible observation skills to record what happens.

Safety Precautions:

Results:

1) Write a short paragraph describing what happened during this experience. This is the place to put your observations. ONLY include facts. DO NOT include an interpretation of the facts. Interpretation means describing why something happened. Include a table to illustrate the results you got from the different concentrations of KI.

Discussion: This is where you interpret your experiment. These are guide questions. Use the checklist for your lab reports.

Sample first sentence: This research demonstrated more oxygen was generated by ……….

What reaction occurred during this experiment?

Which of these products is in its elemental form?

Why did this reaction occur and what made it occur so rapidly?

What did you learn from this experiment?

How did you control the variables in this experiment so that you know your results are just the result of testing the one independent variable you intended to change?.

Conclusion:

My hypothesis is (accepted or rejected) ______

because ______

______.

Practical application or Future research: Write a short paragraph about how the breakdown of hydrogen peroxide could be used by you personally or how knowledge of this process can benefit you or industry. (Yes, you will have to look this up).