Solutions and Mixtures

Section 1: Understanding Solutions and Mixtures

  • A mixture is a combination of two or more substances that retain their own properties and can be physically separated.
  • When a substance dissolves in a solvent to form a solution, it’s known as a solute. The substance in which the solute dissolves is called the solvent.
  • Solutions are homogeneous mixtures where the particles of the solute are evenly distributed throughout the solvent.
  • An example of a solution would be sugar dissolved in water. Here, the sugar is the solute and the water is the solvent.

Section 2: Types of Solutions

  • Solutions can be categorised into different types based on the state of the solute and the solvent: gaseous, liquid, and solid solutions.
  • Gaseous solutions are composed of gases entirely. E.g., the mixture of oxygen and nitrogen in the air.
  • Liquid solutions can have any state of matter as the solute. An example would be saltwater; the liquid solvent is water and the solid solute is salt.
  • Solid solutions have a solid as the solvent: for instance, alloys like brass (a solution of copper and zinc).

Section 3: Concentration of Solutions

  • The amount of solute that is dissolved in a certain amount of solvent is referred to as the concentration of a solution.
  • One way of expressing concentration is molarity (M), which is the number of moles of solute per litre of solution.
  • Solutions can be described as dilute (low solute concentration) or concentrated (high solute concentration).
  • Dilution is the process of decreasing the concentration of a solution by adding more solvent.

Section 4: Solubility and Saturation

  • Solubility is defined as the maximum amount of solute that can be dissolved in a given amount of solvent at a specific temperature.
  • If a solution has reached its maximum solubility, it is said to be saturated. If it has less solute than the max, it’s unsaturated.
  • At a certain temperature, if you continue to add more solute and it fails to dissolve, it indicates that the solution is saturated.
  • Supersaturated solutions contain a higher amount of dissolved solute than could be dissolved by the solvent under normal conditions.

Understanding these aspects of solutions and mixtures enhances comprehension of key chemistry principles and helps in practical chemistry applications like solution preparation and dilution calculations.