6.2 Solutions

Solution:

 is a homogeneous mixture

Homogeneous & Heterogeneous Mixtures

• A mixture is a material that can be separated by physical means into two or more substances

  • For example, when you dissolve sodium chloride in water, you obtain a mixture whose composition depends on the amount of sodium chloride dissolved

  • This mixture can be separated into its components by the physical process of distillation

• Mixtures are classified into two types:

  • Heterogeneous mixtures which consist of physically distinct components with different properties

    • For example, a mixture of potassium dichromate and iron filings which can be separated by the use of a magnet

  • Homogeneous mixtures, also known as solution consist of components with uniform properties

    • Air is an example of a homogeneous mixture of 78 % nitrogen and 21% oxygen gas as well as other gases

• A solution is a homogeneous mixture made up of:

  • The substance being dissolved, the solute

  • A medium of dissolution, the solvent

• Solutions exist in three physical states:

  • Solids, e.g alloys

  • Liquids, e.g sodium chloride in water

    • Liquid solutions where the solute is an ionic compound and the solvent is water are known as aqueous solutions

  • Gaseous, e.g air

Types of solution

Differences between solution and a pure substance with respect to phase change

If we collect the vapor from a boiling aqueous solution, condense it and boil it again it

will boil at 100⁰C.

If we collect the crystals from a freezing aqueous solution, melt it and freeze it again it

will freeze at 0⁰C.

Diagrammatic representations of elements compounds in the 3 states of matter