SOLUTIONS
A homogeneous mixture of two or more substances is called a solution. In a solution there is homogeneity at the particle level. Usually we think of a solution as a liquid that contains either a solid or a liquid or a gas dissolved in it. However, this is not true. We can have a solid solution as in the case of Alloys.
e.g. Air is a mixture of gas in gas. Air is a homogeneous mixture of a number of gases. It's two main constituents of gases are oxygen (21%) and Nitrogen (78%)
*Alloys :– Alloys are homogeneous mixtures of metals and cannot be separated into their components by physical methods. But still, an alloy is considered as a mixture, because it shows the properties of it's constituents and can have variable composition. For example, brass is a mixture of 30% zinc and 70% copper.
*Components of a solutoin :–
The substances present in a homogeneous solution, are called components of the solution. A solution basically has two components i.e. a solvent and a solute.
(a)Solvent :– The component of a solution which dissolves the other component in it self, is called solvent. A solvent is the larger component of the solution. e.g. a solution of sugar in water is a solid in liquid solution. In this solution, sugar is the solute and water is the solvent.
(b)Solute :–The component of the solution which dissolves in the solvent, is called solute. Solute is the smaller component of the solution e.g. solution of iodine in alcohol known as 'tincture of iodine', iodine is the solute.
Similarly, in carbonated drinks (Soda water), carbon dioxide gas is the solute.
Characteristics of a solution :–
Solution is a homogeneous mixtures.
The size of solute particles in a solution is extremely small. It is less than 1 nm in diamter.
The particles of a solution cannot be seen even with a microscope.
The particles of a solution pass through the filter paper. So, a solution cannot be separated by filtration.
The solutions are very stable. The particles of solute present in a solution do not separate out on keeping.
A true solution does not scatter light (because its particles are very small).