How Compounds are Broken Down: Heat & Electricity

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  • 0:15 Compounds
  • 1:30 Heat
  • 2:38 Electricity
  • 4:03 Lesson Summary
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Lesson Transcript
Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Expert Contributor
Matthew Bergstresser

Matthew has a Master of Arts degree in Physics Education. He has taught high school chemistry and physics for 14 years.

Compounds can be broken down into smaller compounds or their basic elements by chemical change. Sometime this breakdown requires energy. Learn how some compounds are broken down with heat or electricity.


If you have a dime, you could break it down into smaller units, like two nickels. You could then take your nickels and break them down further into ten pennies. In chemistry, a compound, which is a substance made up of two or more different elements, is a lot like your dime. Compounds can be broken down into smaller units. Of course, compounds don't break down into nickels and pennies; instead, they break down into either smaller compounds or their basic elements.

Did you ever pop the cap off of a soda bottle and witness the fizz? That is an example of a compound being broken down. A closed soda bottle contains the compound carbonic acid, or H2CO3. When you pop it open, the carbonic acid decomposes into water (H2O) and carbon dioxide (CO2), which provides the bubbles. Water and carbon dioxide are simpler compounds than carbonic acid, but they are still compounds. Therefore, they can break down themselves to leave us with the basic elements hydrogen, oxygen, and carbon. Compounds break down through chemical changes. Sometimes this chemical change requires energy in the form of heat or electricity. In this lesson, we will look at how compounds are broken down using these energy sources.


If you spend any time in a chemistry lab, you will probably encounter a Bunsen burner, which is a gas burner that comes in handy when you are trying to create chemical changes. Heat is an energy source that can cause compounds to break down. This allows the compounds to split into smaller units. One example is the breakdown of mercuric oxide, which has the formula HgO. If you put this compound into a test tube and hold it over a lit Bunsen burner, it will decompose into the elements mercury and oxygen.

In this example, we see the heat caused the compound to break into its basic elements. These elements are like the pennies we discussed earlier, meaning they cannot be broken down any further. However, heat does not always cause compounds to break all the way down to elements. Some compounds break down into simpler compounds. For example, when you add heat to sodium hydroxide it breaks down into the simpler compounds sodium oxide and water.


When you think of electricity, you probably think of it as the wonderful resource that allows you to run your computer and television. However, a chemist might look at electricity as a useful tool for breaking down compounds.

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Additional Activities

Decomposition Reactions

As we have just learned, there's a type of chemical reaction called a decomposition reaction. These reactions only occur when some form of energy is absorbed by a compound. In this extension activity, we're going to look into the specifics of a few decomposition reactions.


Let's look up the following reactions using the internet. Write out the balanced chemical equations, including the type of energy required for the reaction to occur.

  1. Water decomposition reaction
  2. Calcium carbonate decomposition reaction
  3. Silver chloride decomposition reaction
  4. Potassium chlorate decomposition reaction
  5. Iron(III) hydroxide decomposition reaction
  6. Hydrogen peroxide decomposition reaction

Follow-Up Questions

  1. What did you notice about the quantities of the compounds on the reactants' side of the above reactions (left side of the yield sign) and on the products' side of the above reactions (right side of the yield sign)?
  2. Which of the above reactions require heat energy for the decomposition reaction to occur?
  3. Which of the above reactions require electrical energy for the decomposition reaction to occur?
  4. Which of the above reactions require light energy for the decomposition reaction to occur?
  5. Come up with a generalized chemical equation that represents all of the types of decomposition chemical reactions. You can use letters such as AB to represent the reactant compound.
  6. Most of the chemical decomposition chemical reactions you researched required significant effort and energy to occur. Why is it important that decomposition reactions don't easily occur?

Answers to Follow-Up Questions

  1. There is always one reactant and more than one product.
  2. Calcium carbonate, potassium chlorate and iron(III) hydroxide.
  3. Silver chloride and hydrogen peroxide.
  4. AB + energy ⟶ A + B
  5. If it didn't take so much energy for compounds to decompose, a lot of compounds wouldn't exist, if any. Imagine if water easily decomposed into hydrogen gas and oxygen gas. No life would exist.

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