The reaction between ethane and chlorine gas is a radical halogenation reaction, specifically a chlorination reaction. The mechanism for this reaction can be divided into three main steps: initiation, propagation, and termination.1. Initiation:This step involves the homolytic cleavage of the chlorine-chlorine bond in the chlorine molecule, producing two chlorine radicals. This process can be facilitated by heat or light UV radiation .Cl2 2 Cl2. Propagation:The propagation step consists of two sub-steps:a The chlorine radical reacts with ethane, abstracting a hydrogen atom and forming a methyl radical and hydrogen chloride HCl .CH3-CH3 + Cl CH3-CH2 + HClb The methyl radical reacts with another chlorine molecule, forming chloroethane and another chlorine radical.CH3-CH2 + Cl2 CH3-CH2Cl + ClThe chlorine radical produced in this step can then react with more ethane molecules, propagating the chain reaction.3. Termination:The termination step occurs when two radicals react with each other, forming a stable molecule and ending the chain reaction. This can happen in several ways, such as:a Two chlorine radicals reacting with each other:Cl + Cl Cl2b Two methyl radicals reacting with each other:CH3-CH2 + CH3-CH2 CH3-CH2-CH2-CH3 butane c A chlorine radical reacting with a methyl radical:CH3-CH2 + Cl CH3-CH2Cl chloroethane The presence of a catalyst can affect the selectivity of the reaction by promoting the formation of specific products. For example, in the presence of a Lewis acid catalyst, such as aluminum chloride AlCl3 , the reaction can be directed towards the formation of a specific isomer or a more highly substituted product. The catalyst can stabilize the intermediate radicals, lowering the activation energy and increasing the reaction rate. However, it is important to note that radical chlorination of alkanes, like ethane, is generally less selective than bromination or iodination due to the high reactivity of chlorine radicals.