chemical energy

Examples of chemical energy in the following topics:

• Types of Energy

  • The various types of energy include kinetic, potential, and chemical energy.
  • On a chemical level, the bonds that hold the atoms of molecules together have potential energy.
  • This type of potential energy is called chemical energy, and like all potential energy, it can be used to do work.
  • For example, chemical energy is contained in the gasoline molecules that are used to power cars.
  • The molecules in gasoline (octane, the chemical formula shown) contain chemical energy.

• Energy Changes in Chemical Reactions

  • Due to the absorption of energy when chemical bonds are broken, and the release of energy when chemical bonds are formed, chemical reactions almost always involve a change in energy between products and reactants.
  • By the Law of Conservation of Energy, however, we know that the total energy of a system must remain unchanged, and that oftentimes a chemical reaction will absorb or release energy in the form of heat, light, or both.
  • The energy change in a chemical reaction is due to the difference in the amounts of stored chemical energy between the products and the reactants.
  • This stored chemical energy, or heat content, of the system is known as its enthalpy.
  • Describe the types of energy changes that can occur in chemical reactions

• The Role of Energy and Metabolism

  • All organisms require energy to complete tasks; metabolism is the set of the chemical reactions that release energy for cellular processes.
  • Metabolism is the set of life-sustaining chemical processes that enables organisms transform the chemical energy stored in molecules into energy that can be used for cellular processes.
  • Plants convert light energy from the sun into chemical energy stored in molecules during the process of photosynthesis.
  • Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed.
  • For every action that requires energy, many chemical reactions take place to provide chemical energy to the systems of the body, including muscles, nerves, heart, lungs, and brain.

• Transforming Chemical Energy

  • Cellular respiration is the process of transforming chemical energy into forms usable by the cell or organism.
  • An electrical energy plant converts energy from one form to another form that can be more easily used .
  • For example, geothermal energy plants start with underground thermal energy (heat) and transform it into electrical energy that will be transported to homes and factories.
  • ATP is the principle form of stored energy used for cellular functions and is frequently referred to as the energy currency of the cell.
  • This geothermal energy plant transforms thermal energy from deep in the ground into electrical energy, which can be easily used.

• The First Law of Thermodynamics

  • Thermodynamics is the study of heat energy and other types of energy, such as work, and the various ways energy is transferred within chemical systems.
  • For instance, light bulbs transform electrical energy into light energy, and gas stoves transform chemical energy from natural gas into heat energy.
  • Plants perform one of the most biologically useful transformations of energy on Earth: they convert the energy of sunlight into the chemical energy stored within organic molecules.
  • Humans can convert the chemical energy in food, like this ice cream cone, into kinetic energy by riding a bicycle.
  • Plants can convert electromagnetic radiation (light energy) from the sun into chemical energy.

• Other Forms of Energy

  • Thermal, chemical, electric, radiant, nuclear, magnetic, elastic, sound, mechanical, luminous, and mass are forms that energy can exist in.
  • Chemical Energy: This is energy due to the way that atoms are arranged in molecules and various other collections of matter.
  • An example of something that stores chemical energy is food.
  • When your body digests and metabolizes food it utilizes its chemical energy.
  • For example, luminous energy is radiant energy.

• Metabolism of Carbohydrates

  • These large polysaccharides contain many chemical bonds and therefore store a lot of chemical energy.
  • When these molecules are broken down during metabolism, the energy in the chemical bonds is released and can be harnessed for cellular processes.
  • Inside the cell, each sugar molecule is broken down through a complex series of chemical reactions.
  • As chemical energy is released from the bonds in the monosaccharide, it is harnessed to synthesize high-energy adenosine triphosphate (ATP) molecules.
  • During photosynthesis, plants convert light energy into chemical energy by building carbon dioxide gas molecules (CO2) into sugar molecules like glucose.

• Free Energy

  • Since chemical reactions release energy when energy-storing bonds are broken, how is the energy associated with chemical reactions quantified and expressed?
  • Gibbs free energy specifically refers to the energy associated with a chemical reaction that is available after accounting for entropy.
  • Every chemical reaction involves a change in free energy, called delta G (∆G).
  • If a chemical reaction requires an input of energy rather than releasing energy, then the ∆G for that reaction will be a positive value.
  • An important concept in the study of metabolism and energy is that of chemical equilibrium.

• Energy Transformations

  • Energy transformation occurs when energy is changed from one form to another.
  • For example, an internal combustion engine converts the potential chemical energy in gasoline and oxygen into heat energy.
  • The process of photosynthesis is able to transform the light energy of the sun into chemical energy that can be used by a plant with an efficiency of conversion of a mere 6%.
  • This corresponds to zero kinetic energy and thus all of the energy of the pendulum is in the form of potential energy.
  • These figures illustrate the concepts of energy loss and useful energy output.

• Activation Energy

  • This small amount of energy input necessary for all chemical reactions to occur is called the activation energy (or free energy of activation) and is abbreviated EA.
  • During chemical reactions, certain chemical bonds are broken and new ones are formed.
  • Heat energy (the total bond energy of reactants or products in a chemical reaction) speeds up the motion of molecules, increasing the frequency and force with which they collide.
  • The higher the activation energy, the slower the chemical reaction will be.
  • The Arrhenius equations relates the rate of a chemical reaction to the magnitude of the activation energy: