In the combustion reaction of hydrocarbons (such as propane, butane, or gasoline) with oxygen, the reactants are the hydrocarbon fuel and oxygen gas (O2). The products of this reaction are carbon dioxide (CO2) and water vapor (H2O).

The general chemical equation for the combustion of a hydrocarbon fuel with oxygen is:

$$C_x H_y + O_2 -> CO_2 + H_2O$$

Where:

- \(C_x H_y\) represents the hydrocarbon fuel, where 'x' and 'y' are integers representing the number of carbon and hydrogen atoms in the fuel molecule.

- \(O_2\) represents oxygen gas, which is the reactant that combines with the fuel during combustion

- \(CO_2\) represents carbon dioxide, which is one of the products of the combustion reaction

- \(H_2O\) represents water vapor, which is another product of the combustion reaction

The specific reactants (fuel and oxygen) and products (carbon dioxide and water vapor) can vary depending on the specific hydrocarbon fuel being burned.