Endothermic reactions: Absorbing heat

Some reactions absorb energy rather than release it. These reactions are called endothermic reactions. Cooking involves a lot of endothermic reactions — frying those eggs, for example. You can’t just break the shells and let the eggs lie on the pan and then expect the myriad chemical reactions to take place without heating the pan (except when you’re outside in Texas during August; there, the sun will heat the pan just fine).

Suppose that the hypothetical reaction A-B + C → C-A + B is endothermic — so the reactants are at a lower energy state than the products. Figure 1.1 shows an energy diagram of this reaction.

Figure 1.1: Endothermic reaction of A-B + C → C-A + B.