The melting point and solubility `("in" H_(2) O)` of amino acids are generally high. Explain why ?

Explanation

### Step-by-Step Solution:

1. **Understanding the Structure of Amino Acids**:
- Amino acids are organic compounds that contain both an amino group (-NH2) and a carboxyl group (-COOH). In their solid state, they exist as zwitterions, which are molecules that have both positive and negative charges.

2. **Zwitterion Formation**:
- In the solid state, amino acids exist as zwitterions. For example, the amino acid can be represented as NH3^+CHRCOO^−. This zwitterionic form is crucial for understanding the properties of amino acids.

3. **High Melting Point**:
- The zwitterionic form of amino acids is stabilized by strong electrostatic forces of attraction between the positively charged ammonium ion (NH3^+) and the negatively charged carboxylate ion (COO^−).
- These strong ionic interactions require a significant amount of energy to break, resulting in a high melting point for amino acids.

4. **High Solubility in Water**:
- Amino acids are highly soluble in water due to their ability to form hydrogen bonds. The amino group (-NH2) and the carboxyl group (-COOH) can interact with water molecules.
- The nitrogen atom in the amino group can form hydrogen bonds with water, while the oxygen atom in the carboxyl group can also participate in hydrogen bonding. This extensive hydrogen bonding increases the solubility of amino acids in water.

5. **Conclusion**:
- Therefore, the high melting point of amino acids is attributed to the strong electrostatic forces in their zwitterionic form, while their high solubility in water is due to the formation of hydrogen bonds with water molecules.