On the basis of enthalpy of formation, graphite is more stable than diamond, yet diamond does not change into graphite for years. Why ?

Explanation

To understand why diamond does not change into graphite despite graphite being more stable based on enthalpy of formation, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding Enthalpy of Formation**:
- Enthalpy of formation (ΔH_f) is the heat change that occurs when one mole of a compound is formed from its elements in their standard states.
- For carbon, graphite has a lower enthalpy of formation compared to diamond, indicating that graphite is more stable thermodynamically.

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