Which of the following is the most preferred conformation of ethane molecule

Options

A. Staggered
B. Skew
C. Eclipsed
D. None of the above

Answer

To determine the most preferred conformation of the ethane molecule (C2H6), we need to analyze the different conformations: staggered, eclipsed, and skew (or gauche) forms.

### Step-by-Step Solution:

1. **Understanding Ethane Structure**:
- Ethane consists of two carbon atoms (C1 and C2) connected by a single bond, with each carbon atom bonded to three hydrogen atoms.
- The molecular formula is CH3-CH3.

2. **Identifying Conformations**:
- **Staggered Conformation**: In this conformation, the hydrogen atoms on the front carbon (C1) are positioned in such a way that they are as far apart as possible from the hydrogen atoms on the back carbon (C2). This minimizes electron repulsion.
- **Eclipsed Conformation**: In this conformation, the hydrogen atoms on C1 are directly aligned with the hydrogen atoms on C2. This arrangement maximizes electron repulsion due to the close proximity of the electron clouds.
- **Skew (or Gauche) Conformation**: This is an intermediate conformation where the hydrogen atoms are neither fully staggered nor fully eclipsed. The angle between the hydrogens is less than 60 degrees but more than 0 degrees.

3. **Analyzing Stability**:
- The **staggered conformation** is the most stable because it minimizes the repulsion between the electron clouds of the hydrogen atoms. The distance between the hydrogen atoms is maximized, leading to lower energy and greater stability.
- The **eclipsed conformation** is the least stable due to the high repulsion between the overlapping electron clouds of the hydrogen atoms.
- The **skew conformation** is more stable than the eclipsed but less stable than the staggered conformation.

4. **Conclusion**:
- The most preferred conformation of ethane is the **staggered conformation** due to its lower energy and minimized electron repulsion.