The complete combustion of heptane, a hydrocarbon with the chemical formula C7H16, can be represented by the following chemical equation:

$$2C_7H_{16} + 19O_2 → 14CO_2 + 16H_2O$$

In this reaction, two molecules of heptane react with nineteen molecules of oxygen gas (O2) to produce fourteen molecules of carbon dioxide (CO2) and sixteen molecules of water (H2O).