2014-09-18

basics of thermodynamics-part-7

Is water stored behind a dam an example of potential or kinetic energy? What would cause the water to convert to the other form of energy?


Water behind a dam is potential energy because it is stored energy. As water is release from the dam via a spillway or break in the dam it is converted to kinetic energy-energy in motion.

What is chemical energy?
Chemical energy is energy stored in the structure of molecules within the bonds between atoms.  Energy can be added or released from a molecule by changing the arrangement of electrons (rearranging chemical bonds).

What is an Endothermic and Exothermic reaction?
Endothermic
Heat energy is absorbed from the surroundings. The energy level of the products is higher than the energy level of the reactants.

An endothermic reaction would result in products with a higher energy (less stable).

Exothermic
Heat energy is released to the surroundings. The energy level of the products is lower than the energy level of the reactants.

An exothermic reaction would results in products with more stable bonds (lower energy).


Exothermic reactions tend to be spontaneous because they release energy overall (the “ball” is rolling down the hill which releases energy).  Both reactions have a small bump to overcome called the activation energy.