Endothermic and Exothermic Reaction

Exothermic reaction

In the exothermic reaction, heat move from system to surroundings. System get a gain of energy, so the entalpy of the system increase. The value of the entalpy of produce is bigger than entalpy of reactant.

In the exothermic reaction, the value of H = ( - )

Example : C(s) + O₂(g)  CO₂(g) + 393.5 kJ ; H = -393.5 kJ

Endothermic Reaction

In the exothermic reaction, heat move from surroundings to system. Energy released from the system, so the entalpy of the system decrease. The value of the entalpy of produce is smaller than entalpy of reactant.

In the exothermic reaction, the value of H = ( + )

Example : CaCO₃(s)  CaO(s) + CO₂(g) - 178.5 kJ ; H = +178.5 kJ