4.4:
General Properties of Solutions
Mixtures are substances that are composed of varying amounts of two or more types of molecules or atoms. Sand mixed with iron filings and lemonade are both examples of mixtures. Mixtures can be categorized into two types – heterogeneous and homogeneous.
In heterogeneous mixtures, the components are unevenly distributed; hence, they do not exhibit a uniform composition.
In contrast, homogeneous mixtures do have a uniform composition.
For example, lemonade is a homogeneous mixture of lemon juice, sucrose, and water. Each drop of lemonade tastes the same due to the uniform distribution of its ingredients.
A solution is a homogenous mixture of two main substances – the solute and the solvent. The solvent is present in greater quantity than the solute.
For example, in lemonade, water is the solvent, and lemon juice and sucrose are the solutes.
In a solution, the solute and solvent can be in any state of matter: solid, liquid, or gas. The state of the solution is the same as the state of the solvent. The solution itself is a single “phase”, irrespective of the states of the solvent and solutes.
For example, soda is a liquid solution that contains gaseous carbon dioxide and solid sucrose dissolved in water.
When the solvent is water, the solution is called aqueous. Lemonade and soda are both examples of aqueous solutions.
When forming a solution, the solute and the solvent do not chemically react with each other. Instead, the particles are simply redistributed by individual solvent particles surrounding the solute particles and interacting through attractive forces. In the case of an aqueous solution, the dissolving process is called hydration.
In general, the interaction of a solute with any solvent is called solvation.
4.4:
General Properties of Solutions
Many common substances around us exist as a solution, such as ocean water, air, and gasoline. All solutions are mixtures of substances that are composed of varying amounts of two or more types of atoms or molecules. A mixture with a non-uniform composition is a heterogeneous mixture, whereas a mixture with a uniform composition is a homogeneous mixture. The components that make the homogeneous mixture are evenly spread out and thoroughly mixed.
A solution is a homogeneous mixture that is composed of a solvent and a solute. The solvent is present at a significantly greater concentration than the solute. The solute dissolves in the solvent, and the components distribute themselves randomly to form a solution.
The physical state of a solution — solid, liquid, or gas — is typically the same as that of the solvent. There are three main types of solutions; solid solutions, liquid solutions, and gaseous solutions. The solution phase is the same as the solvent phase.
The solution consists of a mixture of separated solute particles (molecules, atoms, and/or ions), each closely surrounded by solvent species. The solvent and solute interact through attractive forces. This process is called solvation. When water is the solvent, the process is known as hydration. Due to solvation, the solute molecules remain dispersed throughout the solution. Solutions in which water is the solvent are called aqueous solutions. For example, ocean water is an aqueous solution of different salts dissolved in water.
This text is adapted from OpenStax Chemistry 2e, Section 11.1: The Dissolution Process.