Amongst the following compounds, identify which are insoluble, partially soluble and highly soluble in water? (i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform (vi) pentanol.

When discussing the solubility of various compounds in water, it's essential to consider their molecular structures and the nature of their interactions with water molecules. Let's break down each of the compounds you've listed to determine their solubility characteristics.

Solubility Overview

Solubility in water is influenced by factors such as polarity, hydrogen bonding, and molecular size. Generally, polar compounds tend to be more soluble in water, while non-polar compounds are less soluble. Here’s how each of the compounds you mentioned stacks up:

1. Phenol

Pheol is a polar compound due to its hydroxyl (-OH) group, which can form hydrogen bonds with water. This makes phenol partially soluble in water. It can dissolve to some extent, but not completely.

2. Toluene

Toluene is a non-polar aromatic hydrocarbon. Its molecular structure lacks polar functional groups, making it insoluble in water. Instead, it tends to dissolve in non-polar solvents.

3. Formic Acid

Formic acid is highly soluble in water. It is a small, polar molecule with a carboxylic acid group that can form strong hydrogen bonds with water molecules, allowing it to dissolve readily.

4. Ethylene Glycol

Ethylene glycol is another highly soluble compound. It has two hydroxyl groups, which enhance its ability to form hydrogen bonds with water, leading to excellent solubility.

5. Chloroform

Chloroform is a non-polar solvent and is considered insoluble in water. Its molecular structure does not allow for significant interaction with water molecules, resulting in poor solubility.

6. Pentanol

Pentanol is partially soluble in water. While it has a hydroxyl group that can form hydrogen bonds, its long hydrocarbon chain makes it less soluble than smaller alcohols. Therefore, it can dissolve to some extent but not completely.

Summary of Solubility

• Insoluble: Toluene, Chloroform
• Partially Soluble: Phenol, Pentanol
• Highly Soluble: Formic Acid, Ethylene Glycol

Understanding the solubility of these compounds helps in various applications, from chemical reactions to environmental science. Each compound's ability to interact with water is a fundamental concept in chemistry that influences its behavior in different contexts.