Question
Sat September 14, 2013 By:
 

Are all combination reaction exothermic and are all decomposition reactions endothermic? And we are given the reaction - Mg+O= MgO. We are asked to list the two mistakes in this reaction. What will be the answer?

Expert Reply
Sat September 14, 2013
Most of the combination reactions are exothermic but not all the combination reactions are exothermic similarly most of the decomposition reactions are endothermic but not not all the reactions are endothermic. For Example oxidation of hydrocarbons is exothermic.
 
2Mg + O2 -> 2MgO
Mg + 1/2 O2 -> MgO
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