Reaction of Aluminum and Bromine

When bromine is introduced into a sealed reaction vessel containing pieces of aluminum foil, a dramatic reaction occurs. After an induction period of a couple of minutes, the reaction mixture begins to flash with yellow light and an orange cloud is produced. This demo is most effective when it is performed in a darkened room. 

Curriculum Notes 

This reaction can be used as an example of a redox reaction and can be used to introduce the concept of ionic vs covalent bonding. It is also an example of an exothermic formation reaction that produces a lot of light, so it can be used to introduce the concepts of exothemicity and enthalpies of formation. You can use the attached PowerPoint slides to illustrate lattice energy using this reaction. Lastly, aluminum bromide is a Lewis acid and its fuming nature illustrates the reactivity of Lewis acids. Bromine is cool! Students love it. Allow about 10 minutes for this demo. More if you plan to use the ancillary materials.

Lead Time 
One day of lead time is required for this project.

2 Al(s) + 3 Br2(l) ==> 2 AlBr3(s)

Aluminum bromide is hygroscopic and fumes in air, forming a white cloud that looks orange because it is mixed with bromine vapor.1 Aluminum has a Pauling electronegativity of 1.5 and bromine has an electronegativity of 2.8. The resulting electronegativity difference of 1.3 for the aluminum-bromine bond falls well within the commonly accepted range for polar covalent bonds. So this is an example of a compound between a metal and a non-metal in which the bonds have a great deal of covalent nature.Since the aluminum bromide produced in this reaction is formed from elements in their standard states, this is an example of a formation reaction. The heat of formation of aluminum bromide is -526 kJ/mol.2This accounts for the exothermic nature of the reaction. Since aluminum bromide is electron deficient, it is a Lewis acid and reacts strongly with water, which accounts for the way it fumes when exposed to the moisture in air. "Some of the aluminum bromide is produced as fumes, causing the white smoke .... In addition, aluminum bromide reacts violently with water to produce HBr and aluminum hydroxide or oxide."3

Bassam Z. Shakashiri, Chemical Demonstrations, A Handbook for Teachers of Chemistry, v.1 (U. of Wisconsin, 1983) 69.

2 "Selected Values of Chemical Thermodynamic Properties." Nat. Bur. Stand. (U.S.) 1952; Circ. 500; p321 (in Shakashiri).

3 Division of Chemical Education, Inc., American Chemical Society, "Reaction of Aluminum With Bromine." Chemistry Comes Alive, 1999, 22 Jun. 2005, <>

  • 10 mL bromine
  • a piece of aluminum foil, c. 5 cm x 5 cm, torn into small pieces
  • reaction vessel
  • vented addition funnel
  • ring stand
  • large ring
  • clamp
  • flask with ground glass neck
  • 2 ground glass stoppers
  • large plastic hose
  • large trash bag
  • rubber band

The addition funnel containing the bromine will be inserted in a flask to prevent the escape of vapors. Remove the addition funnel from the flask and insert it into the reaction vessel. Stopper the flask. Turn the stopcock on the addition funnel to allow the bromine to flow into the reaction vessel containing the aluminum foil pieces. Dim the lights in the room. After a few minutes, the reaction mixture will begin to flash and glow as the aluminum and bromine react. 

Safety Precautions 

Bromine is a strong oxidizing agent. Avoid contact with skin or eyes and avoid breathing vapors. If a bromine spill occurs, evacuate the students, contain the spill with sand, and quench the bromine with 5% sodium thiosulfate solution. The reaction products, which include aluminum bromide and hydrogen bromide, are also toxic and cause burns.

Prep. Notes 

Assemble apparatus as shown in photograph with the aluminum foil pieces in the reaction vessel. Make sure that the hose is fitted tightly into the reaction vessel and that the trash bag is firmly affixed to the other end. The purpose of this device is to allow the vapors and air in the vessel to expand without escaping. Working under the vent hood, carefully pour about 10 mL of bromine into the vented addition funnel and stopper it. Wear gloves and goggles when handling bromine. It is extremely corrosive! Place the stoppered addition funnel containing the bromine in the Erlenmeyer flask with a ground glass neck and clamp the flask to the ring stand so that it cannot be overturned. When this demo is delivered, make sure that the sand container and the sodium thiosulfate solution container are on the cart in case of a bromine spill.

© Copyright 2012 Email: Randy Sullivan, University of Oregon Chemistry Department and UO Libraries Interactive Media Group