Methods of Separating Substances – Maharashtra Board Class 6 Solutions for General Science (English Medium)
- Air is a mixture of gases.
- During the monsoons, alum crystal is swirled through drinking water.
- Iodine (or naphthalene or camphor or sal ammoniac) is a sublimating substance.
Mixtures are formed when substances, solid, liquid or gas, are mixed together.
- We need to separate substances from their mixtures according to our need or convenience.
- For purification of substances which have to be consumed.
- For reusing certain constituents from a mixture.
Various methods are used to separate substances from a mixture. The method used depends on the properties of the constituent substances.
Methods of separating substances from mixtures are
- Magnetic attraction
When some solids are heated, they change directly into a gas and not into a liquid first. This process is called sublimation.
Apparatus: Beaker, spoon and strainer
- Sand gets separated from salt water by straining.
- Sand remains on the strainer and salt water flows out as a filtrate.
- On heating the filtrate, the water evaporates from salt water leaving behind the salt crystals.
Procedure for sublimation:
- In a porcelain bowl, take a mixture of sal ammoniac powder and sand.
- Plug the tube of a funnel with cotton wool and place it upside down over the mixture.
- Slowly heat the mixture.
- After sometime, particles of sal ammoniac get deposited on the inside of the funnel and on the cotton wool plug.
- After cooling, it changes back into a solid and gets deposited on the cotton plug.
- This is how sal ammoniac sublimates and is separated from the mixture.
- Sifting, winnowing
- Picking, sifting
- Picking, sifting
- Filtration, settling and decantation
Sublimating substances: Iodine, sal ammoniac, camphor, naphthalene
Non-sublimating substances: Sand, salt, alum, sugar, water, oil, turmeric
- Settling and decantation