Factors Affecting Solubility and Rate of Dissulation

 

Objectives

At the end of the lesson, you should be able to:

• learn the different factors that affect solubility; and
• identify the factors that affects the rate of solubility.

Solubility

Solubility is the ability of a substance to be dissolved in another substance at a specific temperature and pressure.

• It is also defined as the maximum amount of solute that can be dissolved in a given amount of solvent at a specified temperature and pressure to produce a solution in equilibrium.
• It is usually expressed in grams of solute per milliliters of solvent.

Factors Affecting Solubility

1. Nature of Solute and Solvent

• A solute can only be dissolved in a solvent when they are “alike.” A general rule is “like dissolves like.”

2. Temperature

• The solubility of a solid and liquid solute increases when temperature is increased.
• The solubility of a gaseous solute to a liquid solvent decreases as temperature increases.

3. Pressure

• The effect of pressure is only applicable for the solubility of gases in liquids. The higher the pressure of a gas, the more soluble it is.

Rate of Dissolution

The rate of dissolution is defined as how fast a solute dissolves in a given solvent at a specific temperature. The process of dissolving a solute is called dissolution.

Factors Affecting the Rate of Dissolution

1. Stirring

• Stirring a solute will increase its rate of dissolution. When you stir, solute particles come into closer contact more often with solvent particles.

2. Size of the solute particle

• The smaller the particles of the solute, the faster it dissolves in the solvent. Small particles provide larger surface area for contact with the solvent.

3. Temperature

• As temperature increases, the rate of dissolution of solid and liquid solutes also increases.

4. Amount of solute present in a solution

• When you have little amount of solute in the solution, it is easier to dissolve the same solute in the given solvent. However, when you have a lot of solute already present in the solvent, dissolution takes slowly.

Key Points

• Solubility is the ability of a substance to be dissolved in another substance at a specific temperature and pressure. It is dependent on three factors: nature of solute and solvent, temperature and pressure.
• The rate of dissolution is defined as how fast a solute dissolves in a given solvent at a specific temperature. It is affected by stirring, size of solute particle, temperature, and amount of solute already present in the solution.