The reaction of ethene with bromine in an aqueous solution of sodium chloride is a bit more complex than a simple addition reaction. Here's a breakdown:

1. The Primary Reaction:

* Bromine Addition: Ethene (C₂H₄) readily reacts with bromine (Br₂) via electrophilic addition to form 1,2-dibromoethane (C₂H₄Br₂). This is the main reaction.

```

CH₂=CH₂ + Br₂ → CH₂Br-CH₂Br

```

2. The Role of Water and Sodium Chloride:

* Water's Influence: The presence of water leads to the formation of a small amount of bromohydrin (2-bromoethanol, CH₂Br-CH₂OH). This happens because water acts as a nucleophile and attacks the bromonium ion intermediate formed during the addition of bromine.

```

CH₂Br-CH₂⁺ + H₂O → CH₂Br-CH₂OH + H⁺

```

* Sodium Chloride's Role: Sodium chloride (NaCl) does not directly participate in the reaction with ethene or bromine. Its presence mainly affects the solubility of bromine in the solution.

3. Overall Reaction:

The overall reaction is a combination of the primary bromine addition and the side reaction forming the bromohydrin:

```

CH₂=CH₂ + Br₂ + H₂O → CH₂Br-CH₂Br + CH₂Br-CH₂OH + H⁺

```

Important Notes:

* The presence of NaCl might affect the reaction rate and yield slightly, but its role is minimal compared to water.

* The reaction is typically carried out in a solvent like dichloromethane or chloroform, as bromine is more soluble in these solvents. Water is added in a separate step to facilitate the formation of bromohydrin.

Let me know if you'd like a more detailed explanation of the mechanism for any of these reactions!