Which Example Has Chemical Energy Present In It?

Chemical energy is energy stored in the bonds between atoms and molecules. It is energy derived from chemical reactions and chemical changes. Chemical energy is an extremely important concept in science because many processes we encounter on a daily basis involve chemical energy.

For example, the food we eat contains chemical energy that is released when our bodies break down food through chemical reactions during digestion. The gasoline we put in our cars also contains chemical energy that is released through combustion to power the engine. Batteries, explosives, fireworks, photosynthesis in plants, muscle contraction in animals – all these processes involve chemical energy being converted to other forms of energy.

In this article, we will look at some common examples of where chemical energy is present and how it gets converted to other forms of energy through chemical reactions.


Food is one of the most common examples of chemical energy that we encounter in our daily lives. The chemical bonds between the atoms that make up the molecules of the foods we eat store energy that can later be released. When we metabolize foods, these bonds are broken, releasing the stored chemical energy that our bodies can then use to power biological processes.

Certain types of foods are particularly rich sources of chemical energy. These include fats, carbohydrates, and proteins. Fats contain very energy-dense bonds, with each gram providing 9 calories of energy. Carbohydrates like sugars and starches also have high energy density, providing 4 calories per gram. Proteins contain moderate energy density, supplying 4 calories per gram as well. By consuming these types of food molecules, we intake chemical energy that can then fuel our activities.

Fossil Fuels

Fossil fuels like coal, oil and natural gas contain high amounts of chemical energy locked up in the hydrocarbon bonds that make up these substances. Hydrocarbons are compounds composed of hydrogen and carbon atoms bonded together.

The hydrocarbon molecules in fossil fuels contain a large amount of energy stored in the bonds between the carbon and hydrogen atoms. This chemical energy can be released through the process of combustion, or burning. During combustion, the hydrocarbon molecules react with oxygen, breaking apart the carbon-hydrogen bonds.

This reaction gives off heat energy, as well as producing carbon dioxide and water as byproducts. The amount of heat energy released when burning a fossil fuel depends on the types of hydrocarbons it contains and the bonds between them. This allows fossil fuels like coal, oil and natural gas to be excellent sources of energy for powering engines, generating electricity, and more.


Batteries are a common example of chemical energy being stored and converted into electrical energy. Within a battery, chemical reactions take place between the anode, cathode, and electrolyte that allow electrons to flow and generate electricity.

The anode is the negative electrode, which is oxidized and gives up electrons during the reaction. Common anode materials are zinc, lithium, and magnesium. The cathode is the positive electrode, which is reduced and accepts electrons. Common cathodes include manganese dioxide, silver oxide, and lithium cobalt oxide.

The electrolyte allows ions to flow between the cathode and anode to balance the flow of electrons through the external circuit. In primary batteries the reaction occurs once and cannot be reversed. In secondary batteries or rechargeable batteries, the chemical reaction can be reversed by applying an external electrical current to recharge the battery.

Overall, batteries harness the energy stored in chemical bonds and utilize oxidation-reduction reactions to generate an electrical current that can power numerous devices and applications. The anode, cathode, and electrolyte work together to allow the energy stored in the battery’s chemicals to be released in a controlled manner.


Explosives like TNT, dynamite, and gunpowder contain a lot of chemical energy stored within their hydrocarbon bonds. When the chemicals in an explosive rapidly combust, these bonds break apart very quickly, releasing the stored energy. This generates a huge amount of heat and gas in a fraction of a second, creating a powerful blast wave.

Some key aspects of how explosives release energy:

  • The hydrocarbon molecules in explosives contain carbon and hydrogen atoms bonded together. These C-H bonds have high bond energies, storing chemical energy.
  • When ignited, the explosive’s molecules rapidly break apart into smaller molecules like CO2, H2O, and N2. This happens through combustion reactions.
  • Breaking these strong C-H bonds releases large amounts of energy very quickly. This builds immense pressure as the combustion products expand rapidly.
  • The pressure wave from the expanding gas is the explosive force. It travels outward at supersonic speeds, resulting in the blast effect.
  • The rate of the reaction is extremely fast – within tiny fractions of a second. This rapid energy release is what makes explosives so powerful.

In summary, the large amount of chemical energy stored in the hydrocarbon bonds of explosives can be released almost instantaneously through combustion reactions. This results in a devastating pressure wave that constitutes the explosive force.


Fireworks are an excellent example of chemical energy being released in the form of light, sound, and heat. They work through a chemical reaction between an oxidizer and a fuel, which rapidly converts chemical potential energy into thermal energy in the form of heat and light.

The oxidizer in fireworks is typically a chemical like potassium nitrate, potassium chlorate, or potassium perchlorate. These contain a large amount of oxygen that can be released through the reaction. The fuel is usually a metal powder such as aluminum, magnesium, or iron. When ignited, the oxidizer rapidly oxidizes the metal fuel in an exothermic reaction, reaching extremely high temperatures of over 2000°C.

This heat energy excites electrons in the metal atoms and oxidizer compounds, causing them to emit light across various wavelengths and colors. Additional compounds like strontium, barium, and copper salts are also added to produce vivid colors through this excitation. The rapid expansion of gases creates an audible bang. Thus the chemical reaction results in an impressive visual and auditory display.

The oxidizer and metal fuel, along with binders and color-producing agents, are compacted together efficiently in a firework shell casing. When lit, the fuse ignites a bursting charge that sets off the oxidizer-fuel reaction and ejects the components high into the air where they can burn and emit light and sound. The chemical energy stored in fireworks truly transforms into an exciting pyro musical event.


Digestion is a complex process that breaks down the food we eat into molecules that can be absorbed and used by our cells for energy. This process releases chemical energy that was originally captured through photosynthesis or by consuming other organisms.

Digestion begins in the mouth, where saliva contains enzymes that start breaking down starches into simple sugars. Once food reaches the stomach, gastric juices containing hydrochloric acid and digestive enzymes continue breaking down proteins into amino acids, fats into fatty acids and glycerol, and complex carbohydrates into simple sugars.

In the small intestine, the pancreas releases pancreatic juices containing more enzymes that further digest all major food components. The pancreas also releases bicarbonate to neutralize the acidic gastric juices from the stomach. The liver produces bile, which emulsifies fats to increase the surface area for enzymes to act on them. The walls of the small intestine also secrete enzymes that complete the digestion of peptides to amino acids, nucleic acids to nucleotides and phosphates, and carbohydrates to simple sugars.

The resulting molecules from digestion are small enough to be absorbed through the intestinal wall and into the bloodstream. Cells throughout the body can then use these molecules, particularly the sugars glucose and fatty acids, for cellular respiration. This process generates ATP, the cell’s energy currency, by breaking down sugars and fats and releasing chemical energy that had been produced through photosynthesis.


photosynthesis converts light energy into chemical energy stored in glucose
Photosynthesis is the process plants use to convert sunlight into chemical energy that is stored in glucose molecules. This process occurs in two main stages: light-dependent reactions and light-independent reactions.

In the light-dependent reactions, plants absorb sunlight using chlorophyll in their leaves. The absorbed light energy is used to split water molecules into hydrogen and oxygen. This releases electrons that are then transported to generate ATP and NADPH, which are used as energy carriers.

In the light-independent reactions, also known as the Calvin cycle, the energy from ATP and NADPH is used to fix carbon dioxide from the atmosphere into glucose. This takes place in three main steps: carbon fixation, reduction, and regeneration of the initial carbon acceptor. The end result is a glucose molecule, which stores the captured solar energy in its chemical bonds.

Overall, photosynthesis allows plants to harness the sun’s energy and convert it into carbohydrates they can use for growth and other cellular processes. The chemical energy stored in glucose can then be passed on to other organisms up the food chain when plants are consumed.

Muscle Contraction

Muscle contraction relies on ATP as its chemical energy source. ATP contains high-energy phosphate bonds that can be broken to release energy. During muscle contraction, ATP powers a cyclical process called the cross-bridge cycle.

In the cross-bridge cycle, the heads of myosin proteins bind to actin filaments, forming cross-bridges. The myosin heads pull the actin, shortening the sarcomere and generating force for contraction. This power stroke requires energy from ATP hydrolysis. ATP binds to myosin and is hydrolyzed to ADP and phosphate. This reaction breaks ATP’s high-energy phosphate bonds and liberates energy. The myosin uses this energy to change confirmation and pull on the actin.

After the power stroke, ADP and phosphate are released, and the myosin head detaches from actin. A new ATP molecule then binds to the myosin, providing energy for the next power stroke. This cyclical attachment, pulling, detachment, and re-energizing of myosin heads by ATP allows sustained muscle contraction with repeated force generation.


In summary, we looked at several key examples that demonstrate chemical energy in action. Foods like fats, carbohydrates and proteins all contain chemical energy that is released when we digest them. The burning of fossil fuels like coal, oil and natural gas also involve chemical energy being converted into heat, light and motion. Batteries power many of our electronic devices through chemical reactions that produce electricity. Explosives and fireworks rely on chemical energy being rapidly released through combustion reactions.

Inside living organisms, chemical energy drives important biological processes. Photosynthesis in plants converts light energy into chemical energy that is stored in glucose molecules. Muscle contraction also requires chemical energy obtained from ATP molecules. Understanding the concept of chemical energy helps explain where the energy comes from in all these examples. It underscores how chemical reactions can involve energy transfers that do work or produce heat and light. Studying chemical energy is key for learning how organisms stay alive, how mechanical devices operate, and the scientific principles behind many modern technologies.

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