Is Matter Around us Pure Notes

• A mixture is the combination of two or more substances (elements or compounds) which are not chemically combined with each other and may also be present in any proportion.

For example:

• Sugar solution is a mixture of sugar and water
• Steel is an alloy i.e. mixture of - iron, carbon (0.2 – 2.1%) by weight, some times other elements like manganese, chromium, tungsten, nickel may also be present.
• Air is mixture of gases like oxygen, nitrogen, argon, carbon dioxide and water vapour. 
• Pure gold i.e. 24 carat gold is not useful in making coins or ornaments because it is very soft. It is generally mixed with a small amount of copper or silver and its purity is reduced. This is commonly used in making ornaments and coins etc.

• A Solution can be defined as a homogenous mixture of two or more non-reacting substances whose composition can also be varied within certain limits

Components of a Solution:

• A binary solution has two components or constituents. The relative amounts of solute and solvent in the solution either by mass or by volume represent the concentration of the solution.
• Based upon these, solutions are of different types like dilute, concentrated, saturated and unsaturated.
• The solution having small amount of solute is said to have low concentration. It is known as a dilute solution.
• The solution having a large amount of solute is said to be of high concentration.
• Concentration of solution is normally expressed as mass percent or volume percent.

Mass percent: