Arrange the following compounds in order of their expected increasing solubility in water: Br2, KBr, toluene (C7H8, a constituent of gasoline).

Verified step by step guidance

1. Identify the polarity of each compound. Br2 and toluene are nonpolar, while KBr is an ionic compound which is generally polar.
2. Recall the solubility principle 'like dissolves like'. Polar substances tend to dissolve well in polar solvents (like water), and nonpolar substances dissolve better in nonpolar solvents.
3. Assess the molecular structure and interactions. Br2 is a simple diatomic molecule with weak London dispersion forces. Toluene, although nonpolar, has a larger molecular structure compared to Br2, leading to stronger London dispersion forces.
4. Consider the ionic nature of KBr. Being an ionic compound, it dissociates into K+ and Br- ions in water, which interact strongly with the polar water molecules, enhancing its solubility.
5. Arrange the compounds based on the analysis: Br2 (nonpolar, smallest, weakest interactions), toluene (nonpolar, larger, stronger interactions), KBr (ionic, strongest interactions with water).

Key Concepts

Polarity and Solubility

The principle of 'like dissolves like' states that polar solvents dissolve polar solutes, while nonpolar solvents dissolve nonpolar solutes. Water is a polar solvent, meaning it effectively dissolves ionic and polar compounds, but not nonpolar substances. Understanding the polarity of the compounds in question is essential for predicting their solubility in water.

Ionic Compounds and Solubility

Ionic compounds, such as KBr, typically have high solubility in water due to the strong interactions between the ions and the polar water molecules. When dissolved, the ionic bonds break, allowing the ions to disperse in the solution. This contrasts with covalent compounds, which may not dissociate in water.

Nonpolar Compounds and Solubility

Nonpolar compounds, like toluene (C7H8), have little to no interaction with polar solvents like water, leading to low solubility. Toluene is a hydrocarbon and does not form hydrogen bonds with water, making it less soluble compared to ionic compounds. Recognizing the nonpolar nature of toluene is crucial for understanding its position in the solubility order.