Question

The phenomenon of increasing the solubility of weak electrolytes and non- polar molecules by the addition of a water miscible solvent in which the drug has good solubility is called.

• A. Complexation
• B. Co-solvency
• C. Solubilization
• D. Hydrotrophy

Answer 1

The Correct Option is B

The question relates to the concept of solubility and the enhancement of solubility of certain substances. The phenomenon described is associated with the use of a solvent system that enhances the solubility of a solute, specifically when dealing with weak electrolytes and non-polar molecules. Let's analyze the given options to identify the correct term:

1. Complexation: This involves the formation of a complex compound where metal ions or molecules with unpaired electrons coordinate with ligands. While it can affect solubility, it specifically involves interaction at an atomic or molecular level in coordination chemistry, which is not the primary focus here.
2. Co-solvency: This is the use of a water-miscible solvent to increase the solubility of poorly soluble compounds. By adding a co-solvent that interacts better with the solute than water alone, solubility is enhanced. This matches the given description accurately.
3. Solubilization: This is a general term that refers to the process of making a solute dissolve in a solvent, often using surfactants, which do not apply to the scenario described here involving a water-miscible solvent.
4. Hydrotrophy: This involves adding a large amount of a salt to increase solubility, especially of organic solutes. It works by increasing the water-breaking capacity, substantially different from the co-solvency mechanism.

Based on the definitions and explanations above, the correct answer is Co-solvency. Co-solvency specifically refers to the use of a water-miscible solvent to improve the solubility of weak electrolytes and non-polar molecules, which precisely matches the description given in the question.