The reaction between methane (CH₄) and bromine (Br₂) to produce bromoethane (CH₃CH₂Br) and hydrogen bromide (HBr) is a substitution reaction.

Here's the balanced equation:

CH₄ + Br₂ → CH₃CH₂Br + HBr

However, this reaction is not as straightforward as it seems. It proceeds through a free radical mechanism that requires light or heat to initiate. The mechanism involves several steps, including:

1. Initiation: The Br₂ molecule is broken down into two bromine radicals (Br•) by light or heat.

2. Propagation: The bromine radicals react with methane to produce a methyl radical (CH₃•) and HBr. The methyl radical then reacts with Br₂ to form bromoethane and another bromine radical, continuing the cycle.

3. Termination: Two radicals combine to form a stable molecule.

While the overall reaction is simple to write, understanding the mechanism is crucial to fully grasp the process.