Activity Decomposition of Hydrogen Peroxide (H₂O₂)

EXPLORATION:
1. Have you ever had a cut on your skin that bled? Perhaps you or your parents put
  hydrogen peroxide on it which produces an emission of a white froth and bubbles.
  Since the bubbles oxidize germs, what do you think the bubbles of gas are?

2. Placing a drop of hydrogen peroxide on the table top does not produce bubbles. What
  do you think causes the bubbling when it is placed on an open wound?

EXPLANATION:
  You are correct if you thought that oxygen gas bubbles were produced in the
  decomposition of hydrogen peroxide that kills bacteria and other germs. Oxygen is
  normally a colorless gas; it is its mixing with water from the bottle that causes it to
  have a white frothy appearance. If you have seen water in a lake with "whitecaps"
  from the wind, you understand why the water is frothy white.

  The decomposition of the hydrogen peroxide is caused by a chemical in blood.
  Specifically the chemical is a catalyst that triggers the decomposition. A catalyst is a
  chemical that causes a reaction without itself being part of the reaction. Names of
  catalysts usually end in "ase." Catalase is the name of the catalyst in blood and in
  many other living cells and tissues that decompose hydrogen peroxide (H₂O₂).

3. Explain how an umpire is like a catalyst in a baseball game?

4. Iron in the presence of oxygen causes rust. Once rust is formed, it no longer reacts
  but causes the rest of the iron to rust even faster. Explain how rust is a catalyst for the
  further rusting of iron.

5. Sometimes people are called catalysts. What do you think is meant by this?

Purpose: To determine the presence of a catalyst based on the decomposition of H₂O₂

Materials needed:
  a. small slices of raw apple, potato, piece of bread
  b. yeast (matchhead size) on a 5cm x 5cm aluminum square
  c. eyedropper or Beral pipette for dispensing household hydrogen peroxide
  d. goggles

Procedure:
  a. Place a few drops of hydrogen peroxide (H₂O₂) from your eyedropper or Beral
    pipette on top of small pieces of apple, raw potato, bread, and yeast.
  b. Write your prediction, observations and conclusions in the table below.

              Data Table: Decomposition of H₂O₂
 

	yes bubbles  /  no bublles	catalyst (yes, no)
apple
bread
potato
yeast

6. Which of the above substances have the catalytic ability to decompose H₂O₂ ?

7. Use small circles to draw molecules; darkened circles for oxygen, a smaller circle
  with an H inside for hydrogen. Short lines or circles next to each other indicate
  bonding. H₂O₂ has two oxygen atoms connected to each other.
H₂O₂
 O₂
 H₂O
 

8. Use the information above to complete the equations of the decomposition of H₂O₂