Minggu, 11 Oktober 2009

Endothermic Chemical Reaction

Most endothermic reactions contain toxic chemicals, but this reaction is safe and easy. Use it as a demonstration or vary the amounts of citric acid and sodium bicarbonate to make an experiment.
Difficulty: Average
Time Required: Minutes

Here's How:

  1. Pour the citric acid solution in a styrofoam coffee cup. Use a thermometer or other temperature probe to record the initial temperature.
  2. Stir in the baking soda (sodium bicarbonate). Track the change in temperature as a function of time.
  3. The reaction is: H3C6H5O7(aq) + 3 NaHCO3(s) --> 3 CO2(g) + 3 H2O(l) + NaC6H5O7(aq)
  4. When you have completed your demonstration or experiment, simply wash the cup out in a sink. No toxic chemicals to mess with!


  1. Feel free to vary the concentration of the citric acid solution or the quantity of sodium bicarbonate.
  2. An endothermic is a reaction that requires energy to proceed. The intake of energy may be observed as a decrease in temperature as the reaction proceeds. Once the reaction is complete, the temperature of the mixture will return to room temperature.

What You Need:

  • 25 ml citric acid soln
  • 15 g baking soda
  • styrofoam cup
  • thermometer
  • stirring rod

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