Suppose that you average about 50 miles per hour on interstate high- ways. About how long will it take you to travel from the farthest point north shown on the map to the farthest point south?

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen