User:Sangeetha/Sandbox

MIXTURES

How will you judge whether the given material is pure or not? For a common man pure means without any adulteration.But for scientist pure substance means it is made up of one kind of elements.

For example milk it is made up of proteins,fat and so on. So mixture is a combination of two or more pure substances combined in any fixed proportion. It can be classified into two types namely homogeneous and heterogeneous mixtures.

HOMOGENEOUS MIXTURES

It is in uniform composition throughout the substances.

EXAMPLE 1.salt in water

2.sugar in water

3.ethanol in water

the above mentioned examples are called  SOLUTION which is stable and particle size is very small.So it cannot scatter the beam of light.

HETEROGENEOUS MIXTURES

It is in non uniform composition throughout the substances.

EXAMPLE 1.sand in water

2.sand and camphor

3.chalk in water

the above mention examples are called SUSPENSION which is unstable and particle size is comparatively large.So it can scatter a light.

I HAVE ONE QUESTION WHETHER MILK IS HOMOGENEOUS OR HETEROGENEOUS?????

Student may have misconception that milk is a homogeneous solution.But milk is a heterogeneous which means it is a COLLOIDS.Particle size is small so we cannot see through our naked eyes

but it is enough to scatter a beam of light.This effect is called TYNDALL EFFECT.

It consists of dispersed phase and dispersing medium like solute and solvent in solution.

DISPERSED PHASE      DISPERSING MEDIUM     EXAMPLE

liquid                               gas                                  AEROSOL (cloud, mist)

solid                                gas                                  AEROSOL (dust in air)

solid                                solid                                 SOLID SOL (gemstone)

liquid                               liquid                                EMULSION(paint milk)

PURE SUBSTANCES:

It is made up of only one type of matter.It can be classified into elements and compounds.

ELEMENTS

It cannot be broken down into substances. For example copper, iron, nickel and so on.

COMPOUNDS

It is made up of two elements at fixed proportion.For example water contains two molecules of hydrogen and one molecule of oxygen.

some important changes which has to be clarified:

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