K956: Prep Notes

Introduction

Catalysis of the decomposition of hydrogen peroxide is demonstrated in a foil-covered florence flask or fancy bottle.  A packet of manganese dioxide catalyst is suspended by a thread inside the neck of the bottle.  When the stopper is removed, the packet falls into the hydrogen peroxide.  The products of the decomposition form a large white cloud above the mouth of the flask.                                                                     

2H2O2  —MnO2—> 2H2O + O2

Supplies

Short List

  •   Goggles and gloves
  •   500 mL Florence flask
  •   Bench paper
  •   Kimwipes (3” x 3”)
  •   String (6”)
  •   One hole stopper

Chemicals

  •   2 g. MnO2
  •   30 mL of 30% H2O2

Prior to Lecture  (prep time ~ 5 min.)

  1. Prepare desired number of MnO2 catalyst packets.  Weigh out 2 g. MnO2 for each packet and place on 3"x3" square of Kimwipe.  Tie the edges of the Kimwipe up with a long (6") piece of thread.
  2. Measure 30 mL of 30% H2O2 into desired number of 500 mL florence flasks.
  3. Immediately before lecture suspend the packet of MnO2 by stoppering the flask with a one-hole stopper (to allow gas to escape in case of accidental triggering) and catching the thread between the stopper and the flask.  Move the bottle as little as possible after this is done to keep catalyst from sifting through the Kimwipe.
  4.  Assemble the following:      

            a. gloves

            b. goggles

            c. bench paper

    NOTES:

    12/9/15

    We have both activated and not activated MnO2. Use 2 g of the activated or 4 g of the not activated MnO2.

    4/11/07

    Elaine & Laurel, 

    Aldrich wasn't kidding when they described the manganese dioxide I purchased as "activated".  Four grams of the stuff in 30 mL of 30% hydrogen peroxide will knock your socks off.  Two grams produces a very healthy and active "genie". 

    It's in a 100g Aldrich bottle labeled as manganese (IV) oxide. 

    Bob

    To Conduct Demonstration:

    • Position the covered or opaque bottle in the middle of a piece of bench paper.
    • Pull the stopper out, allowing the MnO2 packet to fall into the flask.

     Waste

    There is a waste container in the hood in the demo room.