Publication No. 12540
Mix together hydrogen peroxide, sodium iodide solution and dishwashing liquid in a tall cylinder and stand back. Your students will observe with amazement a catalyst in action as an enormous amount of soapy foam erupts from “Old Foamey!”
(for each demonstration)
Hydrogen peroxide, 30%, 20 mL*
Sodium iodide solution, 2 M, 5 mL*
Dishwashing liquid, 10 mL*
Food coloring (optional)
Graduated cylinders, 10- and 100-mL
Plastic tray, several inches deep
*Materials included in kit.
Hydrogen peroxide, 30%, will act as an oxidizing agent with practically any substance. This substance is severely corrosive to the skin, eyes and respiratory tract; a very strong oxidant; and a dangerous fire and explosion risk. Do not heat this substance. Sodium iodide is slightly toxic by ingestion. Although the dishwashing liquid is considered non-hazardous, do not ingest the material. Do not stand over the reaction; steam and oxygen are produced quickly. Wear appropriate chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. This activity requires the use of hazardous components and/or has the potential for hazardous reactions. Please review current Safety Data Sheets for additional safety, handling and disposal information.
The foam and solution left in the cylinder may be rinsed down the drain with excess water.
Student Worksheet PDF
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering PracticesAnalyzing and interpreting data
Disciplinary Core IdeasMS-PS1.A: Structure and Properties of Matter
MS-PS1.B: Chemical Reactions
HS-PS1.A: Structure and Properties of Matter
MS-PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
Answers to Questions
Hydrogen peroxide and dishwashing solution were added to a 100-mL graduated cylinder. A small amount of sodium iodide was added, which caused thick foam to erupt from the cylinder.
2H2O2(aq) → 2H2O(g) + O2(g)
The water vapor and oxygen gas get trapped in the dishwashing liquid, causing it to foam.
The sodium iodide served as a catalyst, which is a substance that speeds up a reaction but is not consumed during the reaction. It was not consumed during the reaction.
This demonstration evolves a good deal of heat as shown by the steam coming off of the foam as it is produced. The reaction, therefore, is exothermic. The action of a catalyst is demonstrated. The catalyst is the I–(aq) ion which speeds up the decomposition of the hydrogen peroxide. The decomposition of hydrogen peroxide produces steam and oxygen gas. The oxygen gas and water vapor cause the dishwashing liquid to foam.
Special thanks to Jim and Julie Ealy of The Peddie School in Hightstown, NJ.