Chapter 9 Notes | Chemistry 1st Year
- Concept of a Solution
- Concentration Units of Solution
- Types of Solutions
- Ideal and Non-Ideal Solutions
- Vapour Pressures of Liquid-Liquid Solutions
- Solubility and Solubility Curves
- Colligative Properties of Solutions
- Energetics of Solution
- Hydration and Hydrolysis
- A solution, on average, is a homogeneous mixture of two or more kinds of different molecular or ionic substances. The substance, which is present in a large quantity is called a solvent and the other in small quantity is called a solute.
- Solutions containing relatively lower concentrations of solute are called dilute solutions, whereas those containing relatively higher concentrations of solutes are called concentrated solutions. Solubility is the concentration of a solute in a solution, when the solution is at equilibrium with the solute at a particular temperature.
- The concentration of a solution may be expressed in a number of ways.
- Percentage composition
- Mole fraction
- Parts per million
- Solution may be ideal or non-ideal. Those solutions, which obey Raoult’s law are ideal solutions. Raoult’s law tells us that the lowering of vapour pressure of a solvent by a solution, at a constant temperature, is directly proportional to the concentration of solute.
- Many solutions do not behave ideally, as they show deviations from Raoult’s law. A solution may show positive or negative deviation from Raoult’s law. Such liquid mixtures, which distill without change in composition, are called azeotropic mixtures.
- Colligative properties of a solution are those properties, which depend on the number of solute and solvent molecules or ions and are independentof the nature of solute. Lowering of vapour pressure, elevation of boiling point and depression of freezing point and osmotic pressure are the important colligative properties of solution.