Little packets of energy

“Energy cannot be created nor can it be destroyed. It can only change from one form into another”

Before we discuss the energy stored in atoms and molecules let's recap the structural nature of the atom.

 

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The atom holds two types of stored energy, chemical and nuclear potential energies. We will discuss chemical potential energy in this unit but keep in mind that in the nucleus of an atom there is an incredible amount of energy stored between protons and neutrons and released only during nuclear reactions, as shown on the right.

 

Burning of fuels is a fine example of chemical energy being converted into other forms of energy such as light, heat and sound. Consider the video on the right, it shows a chemical reaction that releases the stored chemical energy in sugar as heat, light and sound.

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A more violent release of chemical energy takes place when hydrogen and oxygen are ignited. During this chemical reaction, hydrogen and oxygen molecules react with each other to form water and in the process release a great deal of energy that characterizes the explosion shown in the video.

 

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The energy is held in the chemical bonds that hold atoms together in the molecule. DUring a chemical reaction molecules break apart and their atoms recombine to form new substances. These substances have atoms held together by chemical bonds with less energy than the reactants. The excess energy is given off as heat, light or sound.

Take the reaction between hydrogen gas and oxygen gas to form water. The water molecule contains less energy than the hydrogen and oxygen molecules that created it. The excess energy is given off as heat and light. This is shown by the energy graph on the right.
Chemical bonds that hold the hydrogen and oxygen atoms together in the water molecule have less energy than the bonds holding the molecules that formed water together.

Molecules with a great deal of energy in their electrons usually prefer to react with other molecules to try and reduce that energy. Molecules, such as nitroglycerine, have a great deal of energy in their bonds and are said to be unstable. Such molecules may react spontaneously or with other molecules to release a great deal of energy.

Such reactions can release so much energy that they are used to launch huge spacecraft into space or as explosive devices.

So where does the energy to lift the shuttle come from?

 

 

A good fuel should contain chemical bonds with

It should then react to form substances with as little energy as possible. Explain why

Good fuels produce gaseous substances when they react. Why is this essential in creating thrust?

Not always is chemical energy converted into heat, light, and sound. Consider the light globe and battery on the right. Chemicals are used in batteries to store energy. is converted into this is then converted into
Continue with photosynthesis.