To determine which compound has the highest boiling point among the given haloalkanes, we will analyze the molecular weights and the structure of each compound. Here’s a step-by-step solution:
### Step 1: Identify the Compounds
The compounds we are comparing are:
1. 1,2-Dibromoethane (Ethylene bromide)
2. 1,2-Dichloroethane
3. 1,1-Dibromoethane
4. 1,1-Dichloroethane
### Step 2: Analyze Molecular Weights
Molecular weight plays a crucial role in determining boiling points. The higher the molecular weight, the higher the boiling point due to stronger van der Waals forces.
- **1,2-Dibromoethane (C2H4Br2)**:
- Molecular weight = (2 × 12) + (4 × 1) + (2 × 80) = 24 + 4 + 160 = 188 g/mol
- **1,2-Dichloroethane (C2H4Cl2)**:
- Molecular weight = (2 × 12) + (4 × 1) + (2 × 35.5) = 24 + 4 + 71 = 99 g/mol
- **1,1-Dibromoethane (C2H4Br2)**:
- Molecular weight = (2 × 12) + (4 × 1) + (2 × 80) = 188 g/mol (same as 1,2-Dibromoethane)
- **1,1-Dichloroethane (C2H4Cl2)**:
- Molecular weight = (2 × 12) + (4 × 1) + (2 × 35.5) = 99 g/mol (same as 1,2-Dichloroethane)
### Step 3: Compare the Molecular Weights
From the calculations:
- 1,2-Dibromoethane: 188 g/mol
- 1,2-Dichloroethane: 99 g/mol
- 1,1-Dibromoethane: 188 g/mol
- 1,1-Dichloroethane: 99 g/mol
### Step 4: Consider the Structure and Surface Area
The boiling point is also influenced by the structure of the compounds:
- **Branched vs. Unbranched**: Branched compounds generally have lower boiling points due to decreased surface area, which affects van der Waals forces.
- **1,2-Dibromoethane** is unbranched, while **1,1-Dibromoethane** is branched.
### Step 5: Conclusion
Since both 1,2-Dibromoethane and 1,1-Dibromoethane have the same molecular weight, we need to consider their structure. The unbranched structure of 1,2-Dibromoethane provides a larger surface area, leading to stronger van der Waals forces compared to the branched 1,1-Dibromoethane.
Thus, **1,2-Dibromoethane (Ethylene bromide)** has the highest boiling point among the given compounds.
### Final Answer
The compound with the highest boiling point is **1,2-Dibromoethane (Ethylene bromide)**.
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