CBSE – 9th Standard Science

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Chapter 2 – Is matter around us pure

  • A mixture contains more than one substance mixed in any proportion.
  • A pure substance consists of a single type of particles.
  • A solution has a solvent and a solute as its components.
  • A Solution is a homogeneous mixture of two or more substances.
  • Air is a homogeneous mixture and can be separated into its components.
  • Brass is mixture of approximately 30% of zinc and 70% of copper
  • By some separation techniques mixtures can be separated into pure substances

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  • Suspension is a heterogeneous mixture here the particles of a suspension can be seen by the naked eye
  • A colloid is also heterogeneous mixture but the size of particles of a colloid is too small to be individually seen by naked eyes
  • Collid do not settle down when left undisturbed.
  • The concentration of a solution is the amount of solute present in a given amount of solution, or the amount of solute dissolved in a given mass or volume of solvent.

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    Separating the Components of a Mixture

  • SEPARATE COLOURED COMPONENT (DYE) FROM BLUE/ BLACK INK

         EVAPORATION


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  • SEPARATE CREAM FROM MILK BY CENTRIFUGATION

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  • SEPARATE A MIXTURE OF TWO IMMISCIBLE LIQUIDS

SEPARATING FUNNEL    image005      

  • SEPARATE A MIXTURE OF SALT AND AMMONIUM CHLORIDE

         SUBLIMATION


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  • SEPARATE THE DYE IN BLACK INK BY CHROMATOGRAPHY

This process of separation of components of a mixture is known as chromatography.

  • SEPARATE A MIXTURE OF TWO MISCIBLE LIQUIDS

         Distillation used for the separation of components of a mixture containing two miscible liquids that boil                    without decomposition and have sufficient difference in their boiling points.
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  • SEPARATE DIFFERENT GASES FROM AIR

Air is a homogeneous mixture and can be separated into its components by fractional distillation.

  • SEPARATE PURE COPPER SULPHATE FROM AN IMPURE SAMPLE

PURIFICATION OF SOLIDS BY CRYSTALLIZATION


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 PURE SUBSTANCES AND MIXTURES

 

  • Elements or compounds just mix together to form a mixture and no new compound is formed. A mixture has a variable composition
  • Elements react to form new compounds. The composition of each new substance is always fixed.
  • Elements cannot be broken down into simpler substances.
  • Sugar, water, methane and salt are some of the examples of compounds
  • Properties of a compound are different from its constituent elements