Publication No. 12258
A spectacular “fireworks” display is initiated by adding just two drops of water to a mixture of dry chemicals.
Ammonium chloride, NH4Cl, 10 g*
Ammonium nitrate, NH4NO3, 100 g*
Zinc dust, Zn, 100 g*
Water, distilled, 1 mL
Beaker, Pyrex®, 50-mL
Ceramic fiber square or heat-resistant surface
Medicine dropper or Beral pipet
*Materials included in kit.
Ammonium nitrate is a strong oxidizer; may explode if heated under confinement or at temperatures of 250 °C; toxic by ingestion and inhalation; skin, eye, and respiratory irritant. Zinc dust can be a dangerous fire risk; may form explosive mixture with air. If allowed to get damp in a confined bottle, heat will be generated and the mixture may even possibly ignite. Ammonium chloride is toxic by ingestion. Zinc oxide fumes, one of the products of the reaction, can be toxic and severely irritating. Do not premix the ingredients before the demonstration. They can react prematurely and, if in a closed container, explode violently. This reaction should only be done in an operating fume hood or possibly out-of-doors due to amount of smoke produced. This reaction also produces a great deal of heat so it is imperative that an insulating material such as the ceramic fiber square be placed under the beaker. Do not scale this reaction up. The demonstrator should wear chemical splash goggles, a chemical-resistant apron and chemical-resistant gloves. Students should wear chemical splash goggles. Please review current Safety Data Sheets for additional safety, handling and disposal information.
Please 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 solid products of this reaction may be disposed of in a landfill according to Flinn Suggested Disposal Method #26a.
Student Worksheet PDF
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering PracticesDeveloping and using models
Obtaining, evaluation, and communicating information
Planning and carrying out investigations
Disciplinary Core IdeasMS-PS1.A: Structure and Properties of Matter
MS-PS3.A: Definitions of Energy
HS-PS1.A: Structure and Properties of Matter
HS-PS3.A: Definitions of Energy
Crosscutting ConceptsEnergy and matter
Stability and change
Cause and effect
Systems and system models
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
The ammonium chloride may have served as a catalyst for any of the steps in the reaction, most likely the first. It may be why the reaction happened almost immediately after the water was added to the mixture in the beaker.
The mechanism of this reaction is complex. It is believed that the heat produced by the addition of water to the zinc dust melts the ammonium nitrate. Once melted, ammonium nitrate volatilizes, producing N2O and H2O. This reaction is catalyzed by chloride ions:
The energy change for the volatilization of ammonium nitrate to nitrous oxide and water is reported to be –23 kJ/mol. As the volatilization proceeds, the heat produced causes the zinc to dissolve in the molten ammonium nitrate. This leads to the rapid oxidation of the zinc, possibly according to the reaction:
Zn(s) + NH4NO3(s) → N2(g) + ZnO(s) + 2H2O(g)
The energy change for this reaction has been calculated to be –466.5 kJ/mol. This tremendous amount of energy produced causes the dispersal of zinc oxide as a white cloud and yellow/white particulate matter.
Cotton, F. A. and Wilkinson, G. Advanced Inorganic Chemistry: A Comprehensive Text; John Wiley and Sons: New York, 1980; p 417.