what are the sources of a chemical energy?
- pisgahchemistLv 74 months ago
Chemical energy .....
Please don't follow the lead of many biology teachers who wrongly state that, "Energy is stored in bonds." They suggest this with the incorrect notion that energy is released when bonds break. That simply isn't the case. It requires the INPUT of energy to break a bond and energy is released when bonds form.
This seems to be handed down from one biology teacher to another, and spills over into chemistry class when the teacher is actually a biology teacher who is out of her league.
Every chemical bond has a corresponding bond energy (see the table below). For instance, it requires 413 kJ be added to break one mole of C-H bonds. Likewise, when one mole of C-H bonds are formed, 413 kJ is released.
Chemical compounds have a certain amount of chemical potential energy, not unlike objects which have gravitational potential energy. A bowling ball placed on the side of a hill has a great deal of gravitational potential energy, and when released, it will roll to the bottom of the hill an minimize the gravitational potential energy. Chemical compounds react to form new compounds because the new compound is lower in chemical potential energy than the reactants.
The chemical potential energy comes from the relative positions of the nuclei and electrons of the bonded atoms, and thus from the attraction and repulsion of all of these particles.
Another form of energy associated with chemical reactions is kinetic energy, aka energy of motion. This is the kind of energy associated with temperature. All molecules are in constant random motion and the amount of motion is proportional to the absolute temperature. In additional the common motion in three dimensions, kinetic energy can also take the form of rotational motion and vibrational motion. We can call this thermal energy. The thermal energy which is transferred during a chemical reaction is called "heat." "Heat" is not something that a substance has, it is the thermal energy which is transferred from one substance to another.
The total energy possessed by a substance is therefore, the sum of the chemical potential energy and the kinetic energy.
- bravozuluLv 74 months ago
By definition I believe that would be chemical reactions. The source of that energy depends on the chemicals. In living things it usually originally comes from light from the sun which is converted into reduced organic compounds like sugar by photosynthesis in plants. That sugar is used as energy to make other compounds. Energy is generally released as they are oxidized eventually to CO2. The energy comes from the chemical bonds that are formed when it is built up in plants by anabolic reactions. Catabolic reactions is breaking them down.. When molecules in plants are made they require energy to elevate the electrons to higher levels which comes from light or sugar which makes other molecules that can be metabolized for energy.. That energy is released when it is oxidized by the cells and to a lesser degree anaerobically.
- Roger the MoleLv 74 months ago
Your question is not clear. Are you asking about how we get energy from chemicals? Or do you want to know where chemicals get their energy from?
But even after you clarify that, the answer will begin with: "There are many ways."