Anything that has mass and occupies space is matter. There are three different physical states of matter in which a substance can exist - solid, liquid and gas.
A particular state of matter can be changed into other states by changing the temperature or pressure.
A solid has a definite size and shape which do not change on their own. A liquid has a definite size or volume and it takes shape of the container in which it is kept. A gas has no shape or size of its own. It occupies entire volume of the container in which it is kept.
Matter can be classified on the basis of its composition as element, compound or mixture. An element is a basic form of matter that cannot be chemically broken down into simpler substances. A compound is a pure substance made from two or more than two elements chemically combined together in a definite proportion by mass.
A homogeneous mixture is a mixture where the substances are completely mixed together and are indistinguishable. A homogeneous mixture is called a solution. A heterogeneous mixture is a mixture where the substances remain separate and the composition is not uniform.
A suspension is a heterogeneous mixture where the dispersed particles are large enough to settle out eventually.
Solution and its concentration
The substance which is present in bigger quantity is normally taken as solvent and substance which is present in smaller quantity is normally taken as solute.
Concentration of a solution: It is defined as the mass of solute present in a definite volume of the solution. It may also be expressed in terms of percent by mass of solute in gram. For example, a solution of 5% sugar by mass means that 100 gram of the solution contains 5 gram of sugar.
Separation of Mixtures
There are a number of methods available to purify and separate substances from a mixture.
1. Separation by using separating funnel
The mixture of two immiscible liquids like oil and water can be separated by this method.
2. Separation by evaporation
This method is used to separate solvent and solid from a solution by heating or by solar evaporation.
3. Separation by filtration
This method is used to separate solids from liquids in heterogeneous mixtures. In filtration, the solid material is collected as a residue on filter paper and the liquid phase is obtained as filtrate.
4. Separation by crystallization
Crystallization is a process of formation of solid crystals from a solution. The process begins by evaporating the liquid allowed to cool slowly to form crystals which can be separated by filtration.
5. Separation by distillation
This method is used to separate a liquid from a solution of a homogeneous mixture. In this process the mixture is boiled in a distillation flask and the vapours are condensed as liquid.
6. Separation based on Magnetic properties
This method is used to separate magnetic and non-magnetic substances from their mixture by using a magnet. For example, iron granules which are magnetic can be separated from non-magnetic substances like sand, sugar etc.