In the Classroom

Science Disciplines Physical Science Topics
  • Chemical Reactions
    • Combustion
Materials
  • A large/tall glass walled vessel. (Aquarium, Terrarium, large beaker/flask, vase)
  • Multiple candles of varying height, from 2-3cm, to 2-3cm shorter than the reaction vessel.
  • Candle stands/securing putty (if the candles are not self-supporting)
  • Fire ignition source (matches, lighter)
  • Sodium Bicarbonate
  • Vinegar
Safety
  • This demonstration utilizes fire. Even though a candle seems like a relatively safe device, it can still burn down a house. Have a fire extinguisher, or fire blanket nearby in the event of accidental ignitions.
  • As heat from the fire rises, especially during the ignition step, it may cause burns to the person lighting the candles, or anyone else who puts their hand over the vessel. Be careful while lighting the candles, and while adding baking soda, or vinegar to the vessel to avoid burns.
Procedure
  1. Arrange the candles such that they are of varying height, and free standing within the vessel.
  2. Pour some sodium bicarbonate into the vessel.
    • A thin layer should cover the entire bottom of the chamber
    • A larger layer should be applied in the case of tall, thin vessels, like vases, or beakers.
    • A larger layer should also be used for a faster demonstration
  3. Ensure there is no wind or air currents that will interfere with the experiment
  4. Light the candles
  5. Pour in enough vinegar to wet all the sodium bicarbonate.
  6. If the candles do not all extinguish, add more baking soda and vinegar slowly to continue the reaction until all the candles have been extinguished.
Questions
  • Why did the fire go out?
  • What was in the bubbles that formed when the vinegar and baking soda mixed
  • What kind of reaction is taking place
Explanation Baking soda and vinegar undergo an acid base reaction that forms CO2 gas. That gas is heavier than air, and will slowly fill the container. When the gas reaches the flame of one of the candles, it will prevent that flame from getting a new source of oxygen, and the flame will extinguish. As the chamber fills with CO2, the candles will go out in shortest to tallest order. Next Generation Science Standards
5-PS1-1. Develop a model to describe that matter is made of particles too small to be seen.
5-PS1-4. Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
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.