Methods of Separation of Mixture

Methods of Separation of Mixture Handpicking It is the method of separating impurities from a mixture by hands. It can be used to separate only impurities that are larger in size like separating stones from grains. Threshing Separation of stones from grains by handpicking The process in which the stalks of wheat from beaten to free it from seeds is called threshing. The grain seeds are separated from stalks by threshing. Winnowing Winnowing is a process used to separate heavier and lighter components of a mixture by wind or by blowing air. Chaff and husk can be separated from grains. Threshing stalks of wheat Sieving Winnowing The process of separating slightly larger particles from a mixture with the help of a sieve is called sieving. Separating pebbles from sand at construction sites, bran from flour. Sedimentation and decantation When the heavier component in a mixture settles after water is added to it, the process is called sedimentation. To separate dust and soil from pulses, rice. Sieving flour Sedimentation Decantation Decantation is a fast method for separating a mixture of a liquid and a heavier solid. In this process, first the solid impurities are allowed to sediment at the bottom of the container. Then, the pure liquid is poured out carefully from the container into another container for example separating sand from water. Decantation Filtration The process of separating solid impurities from a liquid with the help of a filter is called filtration like separating lemon seeds from lemon juice. Filtration This is a method which is the most especially effective for separating suspensions, for example mud in water. We pour the mixture into a funnel fitted with a piece of filter paper. There are tiny holes in the filter paper for the liquid to pass through, the solid particles are too large to do so, and therefore the solid particles will stay on the paper as what we called a solid residue. We called the liquid which pass through the filtrate. Filtration Evaporation The process of conversion of water into its vapour form is called evaporation. Salts from sea are formed by evaporation and common salt is obtained by purification from the mixture.This method can be used to separate out salt from water. Evaporation of salts solution Condensation The process in which vapours gets converted into liquid is called as condensation. Condensation is involved in the regulation of water cycle. Activity To filter chalk power mixed with water. Condensation Steps: • Take a filter paper and fold it to form a cone which is able to fit in a funnel. • Now clamp this funnel on a stand and keep a beaker below it. • Add the chalk powder mixed with water to it. Observation You will observe chalk powder remains on the filter paper while water collects in the beaker. Use of more than one method of separation For separation of some mixtures more than one method is used for e.g. separation of sand from salt. Let us see how it is separated. It takes place through four processes. 1. 2. 3. 4. Decantation Filtration Evaporation Condensation • Add some water to the sand and salt mixture and allow it to settle for some time. The sand has settled at the bottom. Now decant the water. Sand is separated but the salt still needs to be separated from water. Boil the water in a kettle and place a metal plate with ice on it just above the spout of the kettle. Water droplets begin to fall from the metal plate. Collect it in a beaker. Let whole of the water evaporate. What is left behind is the salt. • • • • • Condensation