My PBL Project: Elephant's Toothpaste

Introduction:

Today, we will be learning about the composition of hydrogen peroxide and how sodium iodide acts as a catalyst. Hydrogen peroxide consists of two hydrogen molecules and two oxygen molecules, which creates a powerful oxidizer. Sodium iodide acts as a catalyst, which is a substance to help increase the rate at which a reaction occurs. Scroll down to see the reaction!

Driving Questions:

How does the chemical makeup of hydrogen peroxide contribute to its reaction when combined with sodium iodide?

The chemical makeup of hydrogen peroxide contributes to its reaction by its chemical equation of H2O2, meaning two hydrogen molecules and two oxygen molecules, creating a thermodynamic compound. Because it is a thermodynamic compound, it creates heat, which causes decomposition.

What is the importance of using the sodium iodide and how does it show in the reaction?

The sodium iodide was used as a catalyst, which is something that speeds up the reaction of something else. When adding in the sodium iodide to the hydrogen peroxide, it causes foam to rapidly build up, versus if there was no catalyst being used, the amount of foam or hydrogen bubbles would not be seen.

Materials:

30% Hydrogen peroxide (This is much stronger than the hydrogen peroxide available to the public.)

2M Sodium iodide solution

Food coloring

Graduated cylinder

Small beaker

Dish soap

Safety glasses

Rubber gloves (for clean up)

Plastic tray (to catch the hydrogen peroxide)

Procedure:

1. First, put on safety glasses.

2. Then, measure 20 mL of the 30% hydrogen peroxide in the graduated cylinder and place it on top of the tray.

3. Next, add some liquid dish soap in the graduated cylinder as well.

4. Then, add a few drops of food coloring.

5. Lastly, add 5 mL of the 2M sodium iodide solution and step back to observe the reaction.

How Does This Work?

H2O2 is the scientific name for hydrogen peroxide, which is made up of two hydrogen molecules and two oxygen peroxide. Hydrogen peroxide looks like water (H2O), but the additional oxygen molecule atom results in a powerful oxidizer.

Hydrogen peroxide is thermodynamically unstable, as it decomposes to form water and oxygen. As the rate of decomposition increases, the concentration and pH (the measure of the acidity or basicity of a solution), the cool, and diluted acidic solution stabilize the hydrogen peroxide. The decomposition of hydrogen peroxide creates more oxygen and heat; this can be dangerous because high concentration of hydrogen peroxide on an inflammable substance can cause fire.

The sodium iodide acts as a catalyst, which is a substance that increases the rate of a chemical reaction. It also causes the hydrogen peroxide to decompose into water and oxygen molecules causing oxygen gas (seen occurring above the reaction) and foam.

Application and Extension

Without the sodium iodide to act as a catalyst for the hydrogen peroxide, there wouldn't be a seen reaction or outcome. In a real life situation in which other processes involve catalysts, here are a few to name:

-Washing clothes: laundry detergent, which uses active enzymes as their catalysts, to speed up the breaking down of certain compounds.

-The making of bread and beer: they are made with yeast, which is a living organism that contains enzymes.

-The human body itself: it contains enzymes; without them, the body would not be able to function properly. These enzymes are used by the body to grow, reproduce, create energy.

The end result:

So how does this work? Check out my Background Research Page to find out!