CBSE Class 9 Chemistry Is Matter Around Us Pure?
Classification of MatterClassification of matter as pure substances and mixtures, elements and compounds, and homogeneous and heterogeneous mixtures
Solution, Suspension and Colloidal solutionsSolution, Suspension and Colloidal solutions
Separation of Solid MixturesThe difference in the solubility of the constituents of a solid mixture can be used to separate them.
Sublimate substances can be separated from non - volatile substance like common salt, sand, iron filings, chalk etc. by the process sublimation.
Any mixture with iron as one of its constituent can be separated by using a magnet.
Separation of Liquid MixturesSeparation of liquids is based on difference in densities or boiling point.
Simple distillation: Constituent has a huge difference in boiling point.
Fractional distillation: Difference in boiling point of constituents is less than 25K.
Separating funnel is used to separate the mixture if constituents differ in the densities.
Separation of Soluble SolidsWe use evaporation method to obtain soluble solids such as salt from sea-water and dye from ink.
Crystallisation method is used to obtain pure crystals of copper sulphate, sugar and common salt.
Chromatography is commonly employed to get dyes from ink, components of chlorophyll and detecting poison in contents of bladder.
Separation of Insoluble SolidsThe big sized particle can be separated from a liquid by filtration.
The solid particle which remains behind on the filter paper are called residue and clear liquid obtained is called filtrate.
Fine suspended particles in a liquid are separated by rotating at very high speed. The method is called as Centrifugation.
Types of ChangesIn physical changes, no new substance is formed and the changes are temporary and reversible.
A process in which one substance reacts with another substance to undergo a change in chemical composition is known as chemical change.
Chemical changes are generally irreversible and can only be reversed under extreme conditions.