Introduction

You are already familiar with mixtures. A mixture is a combination of two or more substances: air is a mixture of gases, rock is a mixture of two or more minerals, and so forth. Mixtures are of two broad kinds: homogeneous mixtures, in which the mixing of the components is uniform throughout, and heterogeneous mixtures, which have nonuniform mixing of components.

In Standard XI we studied that homogeneous mixtures are classified according to the size of their constituent particles, as colloids or as true solutions. In this chapter we deal with the properties of homogeneous mixtures, especially of true solutions.

Solutions are commonly found in all life processes -- the body fluids are solutions. Solutions are also important for industrial processes and in many other areas.

A solution is a homogeneous mixture of two or more pure substances. A true solution consists of a solvent and one or more solutes. In this chapter we explore the properties of binary true solutions containing only one solute.