What does one mean by exothermic and endothermic reactions ? Give example also.
Answers
The chemical reactions release energy in the form of heat, light, or sound, are called exothermic reactions. An exothermic reaction occurs when the temperature of a system increases due to the evolution of heat. This heat is released into the surroundings, resulting in an overall negative quantity for the heat of reaction.
An example of an exothermic reaction is the mixture of sodium and chlorine to yield table salt. This reaction produces 411kJ of energy for each mole of salt that is produced:
2Na(s)+Cl
2
(s)→2NaCl(s)+energy
The chemical reactions that must absorb energy in order to proceed are known as endothermic reactions. An endothermic reaction occurs when the temperature of an isolated system decreases while the surroundings of a non-isolated system gain heat. Endothermic reactions result in an overall positive heat of reaction.
Photosynthesis is an example of an endothermic chemical reaction. In this process, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen.
reaction in which heat energy is liberated by the reactants is called exothermic reaction. eg: Carbon + Oxygen gives Carbon Dioxide + Q. reaction in which heat energy is absorbed by the reactants is called endothermic reaction. eg: Nitrogen + Oxygen gives 2 nitrous oxide (2NO) - Q