Question

What types of intermolecular forces give rise to hydration shells in an aqueous solution of sodium chloride?

Short answer

Ion-dipole interactions are the primary forces forming hydration shells in an aqueous solution of sodium chloride.

Step-by-step solution

- Understand Hydration Shells

Hydration shells form when water molecules surround and interact with dissolved ions in an aqueous solution. This process stabilizes the ions in solution.

- Identify Intermolecular Forces

Determine the types of intermolecular forces that can occur between water molecules and the ions in sodium chloride (NaCl). These forces include ion-dipole interactions, hydrogen bonding, and van der Waals forces.

- Focus on Ion-Dipole Interactions

The primary force responsible for the formation of hydration shells around sodium (Na⁺) and chloride (Cl⁻) ions is the ion-dipole interaction. Water molecules, which are polar, align their partial positive charges (H atoms) towards the negative chloride ions and their partial negative charges (O atoms) towards the positive sodium ions.

- Confirm Other Forces

While hydrogen bonding and van der Waals forces also exist in the solution, they play a minor role in the formation of hydration shells compared to the dominant ion-dipole forces.

Key concepts

intermolecular forces

Intermolecular forces are the attractive and repulsive forces between molecules. These forces play a key role in determining the physical properties of substances such as boiling point, melting point, and solubility.
There are several types of intermolecular forces:

• Van der Waals Forces: Weak attractions between all atoms and molecules, due to transient dipoles forming accidentally.
• Hydrogen Bonding: Stronger than Van der Waals forces, occurs when hydrogen is bonded to highly electronegative atoms (like oxygen, nitrogen, or fluorine).
• Ion-Dipole Interactions: This is a type of force that brings the hydration shells into action. It is significant in solutions of ionic compounds in polar solvents.

Each type of force contributes differently to the behavior of substances in various states and conditions. When studying solutions, like the aqueous sodium chloride solution, ion-dipole interactions primarily govern the formation of hydration shells.

ion-dipole interactions

Ion-dipole interactions are a specific type of intermolecular force that occur between an ion and the partial charge of a polar molecule. This is the primary force responsible for the formation of hydration shells in an aqueous sodium chloride solution.

• Appearance in Solutions: When sodium chloride dissolves in water, Na⁺ and Cl⁻ ions are surrounded by water molecules.
• Alignment of Water Molecules: Water, having a polar nature, aligns its partial negative oxygen end towards Na⁺ and the partial positive hydrogen ends towards Cl⁻.
• Stabilization: These interactions stabilize the ions in solution, making it easier for NaCl to dissolve in water.

Understanding ion-dipole interactions helps explain why ionic compounds readily dissolve in polar solvents like water, and how hydration shells form and stabilize dissolved ions.

aqueous solutions

An aqueous solution is any solution where water acts as the solvent. Water's ability to dissolve a variety of substances results from its polar nature and the intermolecular forces it can engage in, including hydrogen bonding and ion-dipole interactions.

• Definition: In an aqueous sodium chloride solution, NaCl is the solute, and water is the solvent.
• Hydration Shells: As NaCl dissolves, water molecules form hydration shells around the resulting Na⁺ and Cl⁻ ions, effectively keeping them separate and in solution.
• Properties of Aqueous Solutions: These solutions are homogeneous and show unique properties like increased conductivity due to the free ions.

Aqueous solutions are vital in many chemical reactions and biological processes. Understanding how hydration shells form and the role of water helps in grasping these crucial concepts.