KIMIA

UNDERSTANDING THE REACTION THERMIC and EXOTHERMIC

The enthalpy change (ΔH) is positive indicates that there are changes in heat absorption or release of heat.

Chemical reactions that release or remove heat is called an exothermic reaction, whereas a chemical reaction that absorbs heat is called endothermic reaction
In endothermic reactions, energy absorbing system. Therefore, the enthalpy of the system will increase. This means the product enthalpy (Hp) is greater than the enthalpy of the reactants (Hr). As a result, the change in enthalpy, the difference between the enthalpy enthalpy reagent product (Hp-Hr) is positive. So the change in enthalpy for the endothermic reaction can be expressed:

ΔH = Hp-Hr> 0 (13)

In contrast, the exothermic reaction, liberate energy system, so that the enthalpy of the system will be reduced, meaning that the enthalpy of the product is less than the enthalpy of the reactants. Therefore, the change in enthalpy are negative. So p can be expressed as follows:

ΔH = Hp-Hr <0 (14)

Enthalpy change of the reaction exothermic and endothermic can be expressed by the energy level diagram