class 6 separation of substances
Chemistry
Mixture: A substance obtained by mixing more than one pure substance
Pure Substance: A substance that is made up of only one kind of particles
Homogenous Mixture: A mixture in which all components are evenly distributed throughout the mixture is called as Homogenous mixture
Heterogenous Mixture: A mixture in which all components are not evenly distributed in a mixture is called as Heterogenous mixture
Aerated drink: A mixture of water, sugar and carbon di oxide
Soluble substances: Substance that dissolve in liquid are called as soluble substances
Insoluble substances: Substances that do not dissolve in liquid is called as insoluble substances
Solute: A substance that dissolve in a solvent to form solution is called as solution
Solvent: A substance in which other materials dissolve is called as solvent
Saturated solution: A solution that does not dissolve any more solution in it is called as saturated solution
Solubility: The ability of the substance to dissolve in water to form solution
Distillation: The method of obtaining a pure liquid from a solution
Miscible liquids: The liquids that mix well with water is called as miscible liquids
Immiscible liquids: The liquids that do not mix well with water is called as immiscible liquids
Separation of Mixture: It means removal of one substance from a mixture of two or more substances
Hand picking: Method of separation of solid substances (stones,sticks etc) by hand from others
Threshing: Threshing is a process of separating grains from harvested stalks of crops
Winnowing: Winnowing is used to separate grains from husk
Sieving: Sieving is used for separating components of mixture on the basis of size
Magnetic separation: The substances that are attracted towards the magnet are separated by this method
Sedimentation: The process of settling down of heavier insoluble components in a mixture
Supernatant: The clear liquid that remains above the sediment
Decantation: The process of pouring out the liquid without disturbing the sediment is called as decantation
Filtration: The process of separating insoluble substances from a mixture using a filter paper/ cloth
Loading: The process of adding Alum in muddy water, that loads mud particles and speed up sedimentation is called as loading
Evaporation: Evaporation is a method used to separate dissolved solid component from a solution by heating
Distillation: It is a method of obtaining a pure liquid from a solution by heating at certain temperature.
Mixtures contain more than one molecule of substance.
Ex: Lemonade — Lemon juice, sugar and water
Tap water — Water, dissolved salts
Sea water — Several salt mixed with water
Milk — Water, cream etc
Wood — Cellulose and water
Air — Mixture of several gases such as oxygen, carbon di oxide, nitrogen, Argon, water vapour etc.
Pure substances: When substance contain more than one type of atom/ molecule it is called as Pure substance Ex: sugar, salt crystals
Different substances present in a mixture is called as components
What are the various properties of Mixture?
- Constituents of mixture may be in any ratio
- Constituents retain their individual properties in mixture
- Constituents can be separated by simple methods
- d) A pure compound has a fixed melting and boiling point
Why separation is necessary?
- To remove the unwanted items that may enter our body and cause illness
- Ex: separating stones from rice before cooking
- Separating chillies in food before kids eating
- Filtration of river water is done to remove harmful substances before they are supplied to our homes
- Respirator devices are used to remove unwanted components from air and to supply oxygen to the patient
Crude oil/petroleum is a mixture of several useful constituents
Petrol, kerosene, diesel,tar are obtained by separating crude oil
Properties commonly used to separate solid from mixture of solids:
- Size, shape, Magnetic properties and solubility
- Method used to remove impurities from water for drinking purpose is called as Reverse osmosis
- Germs are killed by adding chlorine to the water
- Separating funnel is used to separate the two immiscible liquids
- Two miscible liquids that have different boiling points are separated by Fractional distillation
- The solubility of sugar in water increases with increase in temperature
Importance of Water as Solvent
Since water can dissolve a large number of substances in it, it is called as Universal Solvent
Human body:
- Food is reduced to simple substances, dissolved in water and are absorbed by body
- Waste material produced in the body are dissolved in the water and excreted out
Plants:
- Plants absorb nutrients from soil that are soluble in water
- Minerals from root and food from leaves are transported to different part of plant in the form of solutions
Dissolved Oxygen and Carbon dioxide:
- Gases such as Oxygen and carbon dioxide are soluble in water and important for survival of aquatic life
- Fishes breathe in the dissolved oxygen in water through gills
- Aquatic plants use dissolve carbon dioxide in water for photosynthesis
i) Carbon dioxide dissolved in aerated drinks used to give tangy taste
ii) Solubility of gases in water decreases with increase in temperature
iii) Indians was prohibited from producing and selling salt before independence.
iv) Dandi March by Gandhiji on 6th Apr 1930, from Sabarmati ashram to town Dandi on Coast of Arabian Sea
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