Aspirin can be synthesized in the lab by combining salicylic acid ( C 7 H 6 O 3 ) and acetic anhydride ( C 4 H 6 O 3 ) to form aspirin ( C 9 H 8 O 4 ) and acetic acid ( C 2 H 4 O 2 ) . The balanced equation for this reaction is

C4H6O3 + C7H6O3 ==> C9H8O4 + C2H4O2

Explanation:

The synthesis of aspirin an esterification reaction. This is a substitution reaction in which an alcohol (the –OH group in salicylic acid) reacts with acetic anhydride to form an ester, aspirin.

The equation provided above is balanced by making sure all the atoms of the reactants are equal to those of the products. 1mole each of reactants was required and one mole each of the products was formed.

In the equation above:

REACTANT: C = 11, H = 12, O = 6

PRODUCT: C = 11, H = 12, O = 6

Showing they are balanced.

An exothermic reaction is a "reaction for which the overall standard enthalpy change ΔH⚬ is negative." Exothermic reactions usually release heat and entail the replacement of weak bonds with stronger ones.