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Elephants’ Toothpaste

Elephants’ Toothpaste. A tower of foam emerges from a graduated cylinder. Purpose. To observe the rapid decomposition of hydrogen peroxide when treated with a catalyst . Demonstration. bubble. The hydrogen peroxide had a few drops of detergent in it

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Elephants’ Toothpaste

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  1. Elephants’ Toothpaste A tower of foam emerges from a graduated cylinder

  2. Purpose • To observe the rapid decomposition of hydrogen peroxide when treated with a catalyst

  3. Demonstration bubble • The hydrogen peroxide had a few drops of detergent in it • When potassium iodide KI was added it catalyzed the decomposition of the hydrogen peroxide • The oxygen gas bubbled causing the detergent to foam bubble bubble 2H2O2 + O2 2H2O

  4. Concepts 1. Decomposition Reactions 2. Peroxides 3. Gases

  5. 1. Decomposition Reactions • Any reaction of the general form • AB A + B • In a decomposition reaction a single substance breaks into two or more substances • We say the original substance has “decomposed” which means it has broken apart

  6. H O O H 2. Peroxides • A compound which has an oxygen-oxygen bond • Hydrogen peroxide is a common peroxide • Chemical formula H2O2 • Chemical structure

  7. 3. Gases • Occupy much greater volume than the solid or liquid substances from which they are formed • Expand to fill or escape the container they are in • Will foam in the presence of a detergent as in this demonstration

  8. Conclusions • Hydrogen peroxide decomposed to form oxygen gas and water when treated with a catalyst • When trapped in detergent, the oxygen gas bubbles expanded and a foaming tower was produced

  9. Comments • Many different peroxides are known to exist • Benzoyl peroxide is a peroxide used in acne medication which released oxygen to kill facial bacteria

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