Thermodynamically the most stable form of carbon is

Options

A. Diamond
B. Graphite
C. fullerenes
D. Coal

Answer

To determine the thermodynamically most stable form of carbon among diamond, graphite, fullerenes, and coal, we can follow these steps:

### Step 1: Understand the Allotropes of Carbon
- Carbon exists in several allotropes, including diamond, graphite, fullerenes, and coal. Each of these allotropes has different structural and bonding characteristics.

**Hint:** Research the different allotropes of carbon and their properties to understand their stability.

### Step 2: Analyze the Structure of Each Allotrope
- **Diamond:** Has a tetrahedral structure where each carbon atom is bonded to four other carbon atoms, forming a three-dimensional network. This structure is very strong but not the most stable thermodynamically.
- **Graphite:** Consists of layers of carbon atoms arranged in a hexagonal lattice. The layers can slide over each other, which gives graphite its lubricating properties. The bonding within the layers is strong, but the van der Waals forces between the layers are weak.
- **Fullerenes:** Molecules composed entirely of carbon, taking the form of hollow spheres, ellipsoids, or tubes. Their stability can vary based on the specific structure.
- **Coal:** A complex mixture of carbon and other elements, with a poorly defined structure, making it less stable compared to the other forms.

**Hint:** Compare the bonding and structural characteristics of each allotrope to assess their stability.

### Step 3: Evaluate Thermodynamic Stability
- Thermodynamic stability can be assessed through the enthalpy of formation. The lower the enthalpy of formation, the more stable the substance.
- Graphite has a lower enthalpy of formation compared to diamond and fullerenes, indicating that it is more thermodynamically stable.
- Coal, due to its undefined structure, is less stable than graphite.

**Hint:** Look into the enthalpy values of formation for each allotrope to understand their thermodynamic stability.

### Step 4: Conclusion
- Based on the analysis, graphite is the thermodynamically most stable form of carbon due to its layered structure and lower enthalpy of formation compared to diamond, fullerenes, and coal.

**Final Answer:** The thermodynamically most stable form of carbon is **graphite**.