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What is Chemical Energy?

Nicholas Amendolare, John Simmons, Amanda Robb
  • Author
    Nicholas Amendolare

    Nicholas Amendolare is a high school and middle school science teacher from Plymouth, Massachusetts. He has a bachelor's degree in environmental science from Worcester Polytechnic Institute and a master's degree in education from Harvard University. He has been a teacher for nine years, has written for TED-Ed, and is the founder of www.MrAscience.com.

  • Instructor
    John Simmons

    John has taught college science courses face-to-face and online since 1994 and has a doctorate in physiology.

  • Expert Contributor
    Amanda Robb

    Amanda has taught high school science for over 10 years. She has a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. She is also certified in secondary special education, biology, and physics in Massachusetts.

Learn about chemical energy and its different forms. Understand how chemical energy is used, explore how the chemical energy definition applies to different reactions, and see chemical energy examples. Updated: 09/02/2021

What Is Chemical Energy?

Chemical energy can be defined as energy stored in the bonds of chemical compounds. Alkaline batteries, of course, contain chemical energy, but so do substances like gasoline and coal. Even the foods we eat contain chemical energy.

Scientists view energy as the ability to do work, and they often classify forms of energy into two broad categories: kinetic energy (energy due to motion) and potential energy (stored energy). Chemical energy falls into the latter category of potential energy. The energy in gasoline, for example, is stored until combustion takes place, hopefully inside a car's engine, to release it.

Breaking the bonds between atoms requires energy. Forming new bonds between atoms releases energy. Thus, utilizing chemical energy requires understanding the chemistry that will take place once a substance is broken down and reformed.

How It Works

Imagine a molecule of propane, as used in a common grill. The molecule contains three central carbon atoms surrounded by eight hydrogen atoms. Propane, of course, contains chemical energy. But how does one extract it?

When the grill is turned on and the propane is exposed to heat, the atoms begin to move and vibrate. At high enough temperatures, when they are moving fast enough, the propane molecule can fall apart, but only if the atoms have some place to go. In the presence of oxygen, the eleven atoms in the propane molecule will reform into three carbon dioxide molecules and four water molecules.

A propane molecule containing three carbon atoms (black) and eight hydrogen atoms (white).

Propane molecule

Breaking bonds requires energy, and forming new bonds releases energy. So why is the transformation useful? It turns out that the energy released during the formation of the three carbon dioxide and four water molecules is much greater than the energy required to break apart the one propane molecule. Thus, propane is a useful source of chemical energy, as anyone who has cooked hamburgers will attest to. Here's the balanced chemical reaction for that process:

{eq}\rm C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O {/eq}

The reaction above is called exothermic. The term comes from the Greek word exo, which means "outer," and the Greek word therm which means "heat." Exothermic reactions, like the combustion of propane, release more energy than they require. Other examples of exothermic reactions include burning wood, the combustion of gasoline, and even the decomposition of food in a compost pile.

But some reactions, on the other hand, require more energy than they release. These are called endothermic reactions. The word endothermic comes from the Greek word endon meaning "within." If a reaction requires more energy to break its bonds than it releases when it is reforming bonds, then the net result is the subtraction of energy from a system rather than the addition of energy.

Endothermic reactions can be useful too. Disposable ice packs are one example. The bags typically contain water as well as a small pouch of ammonium nitrate. When the pack is squeezed and the small pouch inside is broken, the ammonium nitrate mixes with the water. Because this reaction is endothermic, it uses more energy than it produces. Thus, the ice pack becomes cold, absorbing energy from its immediate surroundings.

What Is Chemical Energy?

Energy is the ability to do work, where work is movement of an object by some force. We use energy every day, and energy comes in different forms. Chemical energy is energy that is stored in chemicals, such as sugar and gasoline. As chemical energy is stored energy, it is a type of potential energy, which is energy stored in objects due to their location. An easy example of potential energy would be that of a bike on top of a hill where the bike's position is elevated and has the ability to roll down the hill. In the case of chemicals, the position refers to the various atoms that exist together within the chemical.

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Chemical Energy Examples

There are myriad examples of chemical energy in our world. Below is a list of a few common chemical energy examples as well as a brief discussion of how energy is stored within the various compounds involved.

Application of Chemical Energy

Now that we understand that chemicals contain potential energy, let's explore the significance of chemical energy. In other words, what does chemical energy do for nature?

Let's play a word association game. What do you think of when I say 'The Circle of Life'? If you're like me, you probably thought of the Disney movie 'The Lion King'. Man that was a great movie! Another way of thinking about the circle of life is in terms of energy utilization within nature. Let me explain. Plants use energy from the sun to make sugar and oxygen from carbon dioxide and water. We, along with other animals, digest that sugar to release energy, so we can do work. Sugar is digested; in other words it's broken down, into carbon dioxide and water, which, in turn, is used by plants to make more sugar.

Are you getting the circle of life?

Solar energy is used by plants to create chemical energy in the form of sugar.
Chemical Energy Examples

Chemical Energy in Everyday Life

We just talked about the fact that plants use solar energy to make sugar from carbon dioxide and water. Sugar, carbon dioxide and water are all chemicals that are held together by what we call chemical bonds or forces that hold the chemicals together. For example, all sugars are composed of carbon, oxygen and hydrogen atoms that are held together by chemical bonds. These atoms don't just stick together automatically. Rather, energy is needed to hold them together. Plants utilize solar energy to put the carbon, the hydrogen and the oxygen atoms together in the form of sugar. This is a really good example of energy transformation where energy is changed from one form to another. In this case, solar energy is converted into chemical energy that holds the sugar together and prevents it from falling apart.

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Video Transcript

What Is Chemical Energy?

Energy is the ability to do work, where work is movement of an object by some force. We use energy every day, and energy comes in different forms. Chemical energy is energy that is stored in chemicals, such as sugar and gasoline. As chemical energy is stored energy, it is a type of potential energy, which is energy stored in objects due to their location. An easy example of potential energy would be that of a bike on top of a hill where the bike's position is elevated and has the ability to roll down the hill. In the case of chemicals, the position refers to the various atoms that exist together within the chemical.

Application of Chemical Energy

Now that we understand that chemicals contain potential energy, let's explore the significance of chemical energy. In other words, what does chemical energy do for nature?

Let's play a word association game. What do you think of when I say 'The Circle of Life'? If you're like me, you probably thought of the Disney movie 'The Lion King'. Man that was a great movie! Another way of thinking about the circle of life is in terms of energy utilization within nature. Let me explain. Plants use energy from the sun to make sugar and oxygen from carbon dioxide and water. We, along with other animals, digest that sugar to release energy, so we can do work. Sugar is digested; in other words it's broken down, into carbon dioxide and water, which, in turn, is used by plants to make more sugar.

Are you getting the circle of life?

Solar energy is used by plants to create chemical energy in the form of sugar.
Chemical Energy Examples

Chemical Energy in Everyday Life

We just talked about the fact that plants use solar energy to make sugar from carbon dioxide and water. Sugar, carbon dioxide and water are all chemicals that are held together by what we call chemical bonds or forces that hold the chemicals together. For example, all sugars are composed of carbon, oxygen and hydrogen atoms that are held together by chemical bonds. These atoms don't just stick together automatically. Rather, energy is needed to hold them together. Plants utilize solar energy to put the carbon, the hydrogen and the oxygen atoms together in the form of sugar. This is a really good example of energy transformation where energy is changed from one form to another. In this case, solar energy is converted into chemical energy that holds the sugar together and prevents it from falling apart.

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Additional Activities

Chemical Energy Around the House

In this activity, students will apply their knowledge of chemical energy to find five different examples in their home. Students might choose something like a battery pack in their phone, their favorite snack, or even the muscles they use to walk around the house. Students might realize it can be difficult to identify chemical energy examples, since we can't see chemical reactions happening. This is addressed in the discussion questions. If students are stuck getting started, help them apply examples in the lesson to their life. For example, in the lesson, sugar is given as an example of chemical energy. Have students apply this concept to realize that all food has chemical energy.

Directions:

In this activity, you're going to be expanding your knowledge of chemical energy by finding five different examples of chemical energy inside your home. For each example, list what the item is in the table below, why it is an example of chemical energy, and how it impacts your daily life. When you're done, answer the reflection questions.

Chemical Energy ExampleWhy Is It Chemical EnergyHow Does It Impact Your Life





Reflection Questions:

  1. What was the most difficult part about finding examples of chemical energy?
  2. How was chemical energy important in your everyday life?
  3. What other forms of energy are important in your daily life? Describe some examples based on the lesson.
Frequently Asked Questions

What are 5 chemical energy examples?

Examples of chemical energy include biomass formed during photosynthesis, petroleum (oil), food, batteries, and hand warmers. Each of these examples has chemical energy stored in the form of potential energy.

What is potential chemical energy?

Potential chemical energy is a form of stored energy. This energy is stored in the bonds between atoms in chemical compounds.

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