Why is impure glycerol by distillation under reduced pressure ?

Explanation

To answer the question "Why is impure glycerol distilled under reduced pressure?", we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Glycerol's Properties**:
- Glycerol has a high boiling point of 563 K (approximately 290 °C) under normal atmospheric pressure.

2. **Decomposition of Glycerol**:
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