How to Create an Exothermic Chemical Reaction

Steel wool

Exothermic chemical reactions produce heat. In this reaction, vinegar is used to remove the protective coating from steel wool, allowing it to rust. When the iron combines with oxygen, heat is released. This takes about 15 minutes.

What You Need

  • Thermometer
  • Jar with lid
  • Steel wool
  • Vinegar


  1. Place the thermometer in the jar and close the lid. Allow about 5 minutes for the thermometer to record the temperature, then open the lid and read the thermometer.
  2. Remove the thermometer from the jar (if you didn't already in Step 1).
  3. Soak a piece of steel wool in vinegar for 1 minute.
  4. Squeeze the excess vinegar out of the steel wool.
  5. Wrap the wool around the thermometer and place the wool/thermometer in the jar, sealing the lid.
  6. Allow 5 minutes, then read the temperature and compare it with the first reading.


  • Not only does the vinegar remove the protective coating on the steel wool, but once the coating is off, its acidity aids in oxidation (rust) of the iron in the steel.
  • The thermal energy given off during this chemical reaction causes the mercury in the thermometer to expand and rise up the column of the thermometer tube.
  • In the rusting of iron, four atoms of solid iron react with three molecules of oxygen gas to form two molecules of solid rust (iron oxide).
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Your Citation
Helmenstine, Anne Marie, Ph.D. "How to Create an Exothermic Chemical Reaction." ThoughtCo, Aug. 25, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 25). How to Create an Exothermic Chemical Reaction. Retrieved from Helmenstine, Anne Marie, Ph.D. "How to Create an Exothermic Chemical Reaction." ThoughtCo. (accessed March 21, 2023).