The reaction C8H18 + Br2 could represent a bromination of octane, possibly resulting in C8H17Br + HBr under appropriate conditions, although multiple products are possible.
The chemical equation provided C8H18 + Br2 --> ? represents the reaction between octane (C8H18) and bromine (Br2), typically a halogenation reaction.
However, without specifying conditions such as light or heat or whether a catalyst is present, it's difficult to predict the exact product. In the presence of UV light or heat, you would get a substitution reaction where bromine replaces one or more hydrogen atoms in octane.
Assuming just one bromine replaces a hydrogen, the equation would be C8H18 + Br2 --> C8H17Br + HBr. This is a simplification as multiple bromination products are possible.
Please note, the equations given in the reference information, like C3H8 + O2 → CO2 + H2O, are for different reactions involving different chemicals (e.g., the combustion of propane), which do not directly pertain to the octane and bromine reaction.