Is matter around us pure notes NCERT 9th

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Introduction

Matter: Anything that occupies space and has mass is called as matter.

Classficiation of matter

1. Pure substance: A substance which shows properties of only one matter. All elements and all compounds are pure substances. E.g. elements such as carbon, hydrogen, gold, silver, iron, oxygen etc. and compounds such as water, sodium chloride etc.
2. Element: A substance which is made up of only one type of atoms is called as element. Total 118 elements are there which may be categorized as metals, nonmetals and metalloids. E.g. elements are given above.
3. Compounds: A compound is formed when two or more elements combine in a fixed ratio of mass. E.g. NaCl (sodium chloride); H₂O (water) etc. A compound shows its own individual properties and does not show the properties of its constituent elements. More than fifty lakh compounds are known till date.
4. Impure substance: A substance which shows properties of two or more substances. E.g. a mixture of sand and water, solution of salt or sugar in water etc. Impure substance are also called as mixtures.
   Impure substances are classified as homogeneous and heterogeneous mixtures

Is matter around us pure notes NCERT 9th

a. Homogeneous mixture: A mixture of 2 or more components that has identical composition throughout. A homogeneous mixture is also called a solution. E.g. solution of salt in water, sugar in water.

b. Heterogeneous mixture: A mixture of 2 or more components that do not have identical composition throughout. E.g. A mixture of sand and water, sand and iron scrub, etc.  A heterogeneous mixture is of two types:-
a. Suspension: A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye. E.g. sand + chalk powder, muddy water, etc.

b. Colloidal solution or colloids: A colloid is a heterogeneous mixture in which particles are uniformly spread throughout the solution particles. In a colloid are being smaller than a suspension cannot be seen by naked eyes. Hence, being heterogeneous it appears to be homogeneous. However, these particles can be seen by a microscope. E.g. Milk, starch solution, etc.

The difference among solution, suspension, and colloid

Saturated solution: A solution in which no more amount of solute can be dissolved at a particular temperature is called a saturated solution.

Supersaturated solution: A solution in which no more amount of solute can be dissolved even on heating, is called a supersaturated solution.

The concentration of a solution: Concentration of a solution means, amount of solute present in a given amount of solution.

Concentration = mass/volume of the solute *100   /    mass/ volume of the solution

Separating the components of a mixture

1. Obtaining coloured component (dye) from blue/black ink (evaporation): if the ink is heated and made to evaporate continuously, the water from the ink evaporated and coloured component (dye) is left. Thus, is because ink is a mixture of dye and water.
   Principle: Non-volatile solute can be separated from volatile solvent by evaporation.
2. Separation of cream from milk (centrifugation):
   Principle: Denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.
   Method: If we take some full-cream milk and centrifuges (spun rapidly) it by using a milk churner, the cream is separated from the milk. Actually, sometimes the solid particles in a liquid are very small and pass through a filter paper. Such mixtures are separated by centrifugation.
   Application:
   1. Used in diagnostic labs for blood and urine test.
   1. Used in diaries and home to separate butter from cream.
   1. Used in washing machines to squeeze out water from wet clothes.

Is matter around us pure notes NCERT 9th

• Separation of a mixture of two immiscible liquids (separating funnel)
  Principle: Immiscible liquids separate out in layers according to their densities.
  Process: We will understand this method with the example of a mixture of kerosene oil and water.
  Fill the mixture in a separating funnel and let it stand still so that separate layers of oil and water formed. Now, open the stopcock of the funnel and pour out the lower layer, i.e. water.
  Close the stopcock as the oil reaches to it.
  This way oil and water are separated.
  Application:
  • To separate mixture of oil and water.
  • In the extraction of iron from its ore.

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