Separation of Substances
In nature, substances are often found in the impure state or mixed with other substances. A pure substance is made of only one type of atoms or molecules. Its components cannot be further separated by physical methods.
A mixture is an impure substance which contains different types of molecules (pure substances). It is a physically formed blend of two or more dissimilar substances.
Need for Separation of Mixtures
• To separate two or more substances, each being useful to us
• Examples: Rice and flour, sand and pebbles, kerosene and petrol, salt and iodine
• To separate useful substances from non-useful ones Examples: Sand and water, dirt and clothes, iron and garbage
• To separate impure or harmful substances from useful ones Examples: Stone and rice, pesticides and water, weeds and crops