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Firefly Reaction


Bromine is corrosive and toxic. Wear gloves and dispense it in a hood.

Chemicals and Solutions

approximately 15 mL bromine


  • 3L erlenmeyer flask with stopper to fit
  • aluminum foil
  • steel wool
  • scissors


  1. Place the bromine in the erlenmeyer and stopper the flask.
  2. Gently rub the aluminum foil with steel wool to score the surface. Cut the foil into tiny squares.
  3. Add a handful of aluminum squares to the flask of bromine. Dim the lights. In about one minute you should see the "firefly" flashes of light produced from the reaction of aluminum with bromine. After the reaction is over, you may see a white coating of aluminum bromide on the flask.

Hint: It is important to score the aluminum foil so that aluminum is exposed through the aluminum oxide coating.

Do not use extra thick foil, the reaction can take off!


\( \ce{ 2Al_{(s)} + 3Br2_{(g)} -> 2AlBr3_{(s)} ~~~~ \Delta H_{rxn}^{{o}} = -1054.4KJ/Mol } \)