Teacher Notes
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The Hydrogen Peroxide RainbowDemonstration Kit
Publication No. 14126
IntroductionProduce a rainbow of colors by demonstrating how hydrogen peroxide can both oxidize and reduce. Hydrogen peroxide, a colorless solution, will cause another colorless solution to turn yellow, then red-orange. It also has the ability to make a purple solution go through a color change with the end solution being colorless. Concepts
MaterialsHydrogen peroxide solution, H2O2, 6%*
Potassium iodide solution, KI, 0.12 M, 50 mL* Potassium permanganate solution, KMnO4, 0.004 M, 50 mL* Sulfuric acid solution, H2SO4, 1 M, 18 drops* Beakers, 250-mL, 2 Graduated cylinders, 50- or 100-mL, 2 Overhead projector (optional) Stirring rod or magnetic stirrer *Materials included in kit. Safety PrecautionsTreat the sulfuric acid solution as you would concentrated sulfuric acid; severely corrosive to skin, eyes and other tissue. Hydrogen peroxide solution is an oxidizer and corrosive to skin, eyes and other tissue. Potassium permanganate solution is an oxidizing agent and strong skin irritant; common cause of eye accidents. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please review current Safety Data Sheets for additional safety, handling and disposal information. DisposalPlease consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. The solution from Part A may be reduced according to Flinn Suggested Disposal Method #12a. The solution from Part B may be neutralized according to Flinn Suggested Disposal Method #24b. ProcedurePart A
Part B
Student Worksheet PDFTeacher Tips
Correlation to Next Generation Science Standards (NGSS)†Science & Engineering PracticesAnalyzing and interpreting dataConstructing explanations and designing solutions Engaging in argument from evidence Obtaining, evaluation, and communicating information Disciplinary Core IdeasMS-PS1.B: Chemical ReactionsHS-PS1.B: Chemical Reactions Crosscutting ConceptsCause and effectStability and change Performance ExpectationsMS-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
DiscussionThe reactions that take place in Parts A and B are oxidation–reduction (redox) reactions. Hydrogen peroxide can act as both a strong oxidizing agent and a weak reducing agent. A reducing agent is oxidized in a redox reaction. This means it loses electrons, causing its oxidation number to increase. An oxidizing agent is reduced in a redox reaction, thereby gaining electrons and causing its oxidation number to decrease. {14126_Discussion_Equation_1}
In Part B, hydrogen peroxide, in the presence of strong oxidizer permanganate, MnO4–, now acts as a reducing agent, reducing Mn(7+) to Mn2+. Mn2+ is not initially produced. Mn(7+) is first reduced to Mn(4+) producing a brown precipitate in solution. Mn(4+) is then reduced to Mn2+, giving a clear solution. Part B Reactions {14126_Discussion_Equation_3}
ReferencesSpecial thanks to Jim and Julie Ealy, The Peddie School, Hightstown, NJ, who provided Flinn Scientific with the instructions for this activity. |