Solvent and Solute

Solvents and solutes are not just substances used in chemical laboratories, we use them everyday in our lives. Mixing salt in water creates a solution, with water as the solvent, and salt as the solute that gets dissolved into the water.

Related Terms

• Solvent: It is the substance into which another substance (lesser in amount) gets dissolved.
• Solute: It is the substance that dissolves into the solvent.
• Solution: Mixture formed when a solute dissolves into a solvent.

• Solubility: It is the property of a substance that describes its ability to dissolve into another substance.
• Homogenous Mixture: It is formed when the solute dissolves completely into the solvent, and is present uniformly in the solution.

Many of the products that we use in everyday life are prepared by mixing one or many solutes into one or many solvents, to form a solution. A solution need not be just a liquid. All homogenous mixtures containing solutes and solvents are termed as solutions, whether they are in a solid, liquid, or gaseous state, or any combination of these.

Commonplace products like soaps, glues, paints, medicines, tea, and so on, are all good examples of solutions. Many other substances like steel (formed by mixing carbon solute into iron), and air (nitrogen is the solvent and other gases act as solutes), are all solutions. In a solution, the solute particles get evenly distributed throughout the solvent at a molecular level. The solvent and solute molecules interact with each other, and the reaction produces new chemical compounds.

Whether solvents and solutes will mix together to form a solution, depends on whether they get attracted towards each other at the molecular level. The solute dissolves into the solvent when the attractive forces between the solvent and solute molecules are strong enough to overcome the molecular forces holding the solvent-solvent particles and solute-solute particles together.

The solubility or the ability of a solute to dissolve into a solvent, depends largely on its polarity. The polarity depends on the distribution or alignment of electrons across a molecule. The basic rule of thumb related to solubility factor is: like dissolves like.

This means that a polar solute will readily dissolve into a polar solvent, while a non-polar solute is more likely to dissolve into a non-polar solvent. Other factors like volume of the solvent and the solute, and temperature, also affect the solubility of a substance.

Characteristics of Solvents

• A solvent is usually a liquid, but can also be a solid substance, or a gas.
• Solvents usually have a low boiling point and evaporate easily.
• Many solvents have a characteristic odor and color.
• Most commonly-used solvents contain the carbon element. These are called organic solvents. Others are called inorganic solvents.

• The most common solvent in everyday life is water.
• Some organic solvents such as benzene and tetrachloroethylene are used extensively in the chemical industries.
• Solvents are also used for controlling temperature in a solution, either to increase the speed of the reaction with the solute, or to absorb the heat that is generated during some reactions.

Characteristics of Solutes

• Solutes can be liquids, solids, or gases.
• They usually have higher boiling points as compared to solvents.
• Sugar or salt in water, salt in seawater, and oxygen in the air, are common examples of solutes.

• The solubility of a solute can be increased by increasing the surface area of its particles, by breaking them into smaller pieces (in case of solutes in a solid state).
• In case of gaseous solutes, the pressure affects the solubility, apart from the temperature and volume factors.

• The solubility of a solute also depends on the nature of both the solute, as well as the solvent.

Water, as a solvent, is capable of dissolving a wide variety of substances. A water molecule (H₂0) has an oxygen atom at one side, and hydrogen atoms placed further apart from it. The arrangement of oxygen and hydrogen atoms makes it very polar in nature, and so it is attracted to many different types of molecules. Apart from its chemical composition, its physical attributes and its abundance make it a truly universal solvent!