Based on relative bond strengths, classify these reactions as endothermic (energy absorbed) or exothermic (energy released)
endothermic
b2+c2--> 2bc
a+bc--> ab+c

exothermic
ab+c--> ac+b
a2+c2--> 2ac
a2+b2--> 2ab

Exothermic reaction is a chemical reaction that releases energy. This reaction releases heat energy or light . In an endotermic reaction energy is used. Enthaply is the heat energy change , delta H. If the sum of the enthalpies of the reactans is greater than the products the reaction is exothermic. If the products side has a larger enthaply than the process is endothermic. So, if delta H is negative then the process is exothermic. If delta H is positive, than the process is endothermic. Exothermic are: A+BC -> AB+C A2+B2 -> 2AB Endothermic are:AB+C -> AC+B A2 + C2 -> 2AC B2+C2 -> 2BC