To determine how glacial acetic acid is obtained, we need to analyze the given options and understand the characteristics of glacial acetic acid.
### Step-by-Step Solution:
1. **Understanding Glacial Acetic Acid**:
- Glacial acetic acid is the anhydrous form of acetic acid, meaning it contains very little to no water.
2. **Analyzing the Options**:
- **Option A: Distilling Vinegar**:
- Vinegar is a dilute solution of acetic acid. Distillation can concentrate acetic acid, but it may still retain some water, making it less effective for obtaining pure glacial acetic acid.
- **Option B: Crystallizing, Separating, and Melting Acetic Acid**:
- This method involves cooling acetic acid to crystallize it, then separating the crystals, and finally melting them. This process can yield pure acetic acid with minimal water content, making it the best option for obtaining glacial acetic acid.
- **Option C: Treating Vinegar with a Dehydrating Agent**:
- While this might remove some water, it does not guarantee the production of pure acetic acid, as the reaction may not be complete or may lead to other products.
- **Option D: Chemically Separating Acetic Acid**:
- This option suggests using another chemical to separate acetic acid. However, this method may still leave some water in the product, which is not desirable for obtaining glacial acetic acid.
3. **Conclusion**:
- After analyzing all options, **Option B (Crystallizing, Separating, and Melting Acetic Acid)** is the most effective method for obtaining glacial acetic acid, as it ensures the least amount of water is present.
### Final Answer:
**Glacial acetic acid is obtained by crystallizing, separating, and melting acetic acid (Option B).**
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