In this chapter we have discussed about according to science what is pure, about mixtures and how to separate their components.

1. IS MATTER
AROUND US PURE
BHARAT GURUKUL

2. HOW DO WE JUDGE WHETHER MILK, GHEE,
BUTTER, SALT, SPICES, MINERAL WATER OR JUICE
THAT WE BUY FROM THE MARKET ARE PURE ?

3. INTRODUCTION
• Matter- It is made up of one or more components known as
substances.
• A substance is a kind of matter which cannot be separated into any
other types of matter by some physical means.

4. Matter
Pure
substance
Elements Compound
Impure
substance
(mixture)
Homogeneous Heterogeneous

5. Element
Metal Metalloids Non-metal

6. PURE SUBSTANCE
• Pure substance consist of a single type of substance.
• Pure substance cannot be separated into other substances by physical
methods.
• Pure substance has it’s own definite properties.
• Pure substance has a fixed melting and boiling point.
• Examples- Water, Hydrogen, Carbon etc.

7. PURE SUBSTANCE
ELEMENT
• An element is the
simplest or basic form
of matter that cannot
be broken down into
simpler substances by
chemical reaction.
COMPOUND
• A compound is a
substance composed of
two or more elements,
chemically combined
with one another in a
fixed proportion.

8. TYPES OF ELEMENT
1. Properties of Metal
1. They have a lustre (shine).
2. They have silvery- grey or golden yellow colour.
3. They conduct heat and electricity.
4. They are ductile(can be drawn into wires).
5. They are malleable(can be hammered into thin sheets).
6. They are sonorous (make a ringing sound when hit).
Examples- Gold, Silver, Copper, Iron etc.

9. 2. Properties of Non- Metal
1. They display variety of colours.
2. They are poor conductor of heat and electricity.
3. They are not lustrous, sonorous or malleable.
Examples- Hydrogen, Oxygen, Iodine, Sulphur, Bromine, carbon etc.
3. Some elements have intermediate properties between those of metals and non-
metals, they are called metalloids.
Examples – Boron, Silicon, Germanium etc.
Silicon Boron
Sulphur
Carbon

10. MIXTURE

11. MIXTURE
• Mixture consists of two or more pure substances.
• Mixture can be separated into its components by physical method.
• Mixture shows the properties of it’s components.
• Does not have a fixed melting and boiling point.
• Examples- salt solution, sugar solution, milk, water and sand etc.

12. TYPES OF MIXTURE
1. Homogeneous mixture
• A mixture is said to be homogeneous the different constituents or substances
present in it exist in one single phase without any visible boundaries of
separation in them.
• A homogeneous mixture has a uniform composition throughout.
• Examples- Sugar solution, Salt solution, Air etc.

13. 2. Heterogeneous mixture
• A mixture is said to be heterogeneous if it does not have a uniform composition
and also has visible boundaries of separation between the constituents.
• Examples- mixture of water and sand, mixture of oil and water etc.

14. MIXTURES AND COMPOUND
Mixtures
• Elements or compound just mix
together to form a mixture and no
new compound is formed.
• A mixture has a variable
composition.
• A mixture shows the properties of
the constituent substances.
• The constituents can be separated
fairly easily by physical methods.
Compound
• Elements react to form new
compounds.
• The composition of each new
substance is always fixed.
• The new substance has totally different
properties.
• The constituents can be separated only
by chemical or electrochemical
reactions.

15. WHAT IS A SOLUTION?
• A solution is a homogeneous mixture of two or more substances.
• A solution has a solvent and a solute as its components.
• Solvent - The component of the solution that dissolves the other component in
it(usually the component present in larger amount) is called the solvent.
• Solute - The component of the solution that is dissolved in the solvent(usually
present in lesser quantity) is called the solute.
• Examples- solution of sugar is a solid in liquid solution in this sugar is solute and
water is solvent.

16. SOLUTE AND SOLVENT
Solute + Solvent = Solution

17. PROPERTIES OF SOLUTION
• A solution is a homogeneous mixture.
• The particles of a solution are smaller than 1 nm(10^-9 metre) in diameter. So,
they cannot be seen by naked eyes.
• Because of very small particles size, they do not scatter a beam of light passing
through the solution. So, the path of light is not visible in a solution.
• The solute particles cannot be separated from the mixture by the process of
filtration. The solute particles do not settle down when left undisturbed, that is,
a solution is stable.

18. WHAT IS 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. Example- Flour and Water

19. PROPERTIES OF A SUSPENSION
• Suspension is a heterogeneous mixture.
• The particles of a suspension can be seen by the naked eye.
• The particles of a suspension scatter a beam of light passing through it and make
its path visible.
• The solute particles settle down when a suspension is left undisturbed, that is, a
suspension is unstable. They can be separated from the mixture by the process
of filtration
• When the particles settle down, the suspension breaks and it does not scatter
light any more.

20. WHAT IS A COLLOIDAL SOLUTION?
• The particles of a colloid are uniformly spread throughout the solution.
• Due to the relatively smaller size of particles, as compared to that of a suspension, the mixture
appears to be homogeneous . But actually , a colloidal solution is a heterogeneous mixture
• Example- milk
• Because of the small size of colloidal particles, we cannot see them with naked eyes. But,
these particles can easily scatter a beam of visible light. This scattering of beam of light is
called the Tyndall effect .
• They do not settle down when left undisturbed , that is, a colloid is quite stable.

21. TYNDALL EFFECT

22. • Colloid cannot be separated from the mixture by the process of filtration.
But, a special technique of separation known as centrifugation can be used
to separate the colloidal particles.
• The components of a colloidal solution are dispersed phase and dispersed
medium.
Dispersed phase-The solute like component or dispersed particles in a colloid
form the dispersed phase.
Dispersing medium- The component in which the dispersed phase is
suspended is known as the dispersing medium.

23. Dispersed phase Dispersing medium Type Examples
Liquid Gas Aerosol Fog, clouds, mist
Solid Gas Aerosol Smoke, automobile exhaust
Gas Liquid Foam Shaving cream
Liquid Liquid Emulsion Milk, face cream
Solid Liquid Sol Milk of magnesia, mud
Gas Solid Foam Foam, rubber, sponge
Liquid Solid Gel Jelly, cheese, butter
Solid Solid Solid sol Colured gemstone, milky glass
COMMON EXAMPLES OF COLLOIDS

24. Fog Smoke Shaving cream
Milk
Mud Foam
Jelly
Coloured gemstones

25. SEPARATING THE COMPONENTS OF A
MIXTURE
• Heterogeneous mixtures can be separated into their respective
constituents by simple physical methods like handpicking, sieving,
filtration etc.
• Sometimes special techniques have to be used for the separation of
the components of a mixture.

26. HOW CAN WE OBTAIN COLOURED
COMPONENT(DYE) FROM BLUE/BLACK INK ?
• Ink is a mixture of a dye in water.
• Thus, we can separate the volatile component(solvent) from its non-volatile
solute by the method of evaporation.

27. HOW CAN WE SEPARATE CREAM FROM
MILK ?
• Centrifugation – It is based on the principle that the denser particles are forced
to the bottom and the lighter particles stay at the top when spun rapidly.

28. APPLICATIONS
• Used in diagnostic laboratories for blood and urine tests.
• Used in dairies and home to separate butter from cream.
• Used in washing machines to squeeze out water from wet clothes.

29. HOW CAN WE SEPARATE A MIXTURE OF
TWO IMMISCIBLE LIQUIDS?
• The principle is that immiscible liquids separate out in layers depending on their
densities.

30. APPLICATIONS
• To separate mixture of oil and water.
• In the extraction of iron from its ore, the lighter slag is removed from
the top by this method to leave the molten iron at the bottom in the
furnace.

31. HOW CAN WE SEPARATE A MIXTURE OF SALT
AND CAMPHOR ?
• To separate such mixtures that contain a sublimable volatile component from a
non- sublimable impurity, the sublimation process is used.
• Some examples- naphthalene, anthracene and ammonium chloride.

32. IS THE DYE IN BLACK INK A SINGLE
COLOUR ?
• The ink that we use has water as the solvent and the dye is soluble in it.
• Usually , a dye is a mixture of two or more colours.
• The coloured component that is more soluble in water, rises faster and in this way the colours
get separated.
• This process of separation of components of a mixture is known as chromatography.
• Kroma in Greak means colour.

33. APPLICATIONS
• To separate
1. Colurs in a dye
2. Pigments from natural colours
3. Drugs from blood.

34. HOW CAN WE SEPARATE A MIXTURE OF
TWO MISCIBLE LIQUIDS?
• Distillation – it is 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.
• To separate a mixture of two or more miscible liquids for which the difference in boiling points
is less than 25 k, fractional distillation process is used
• Examples- for the separation of different gases from air, different factions from petroleum
products etc.

35. HOW CAN WE OBTAIN DIFFERENT GASES
FROM AIR ?
•
• Air is a homogeneous mixture and can be separated into its components by
fractional distillation.

36. SEPARATION OF COMPONENTS OF AIR

37. HOW CAN WE OBTAIN PURE COPPER
SULPHATE FROM AN IMPURE SAMPLE?
• Crystalliasation – It is a process that separates a pure solid in the form of crystal
from a solution.
• This technique is better than simple evaporation technique as-
• Some solids decompose or some like sugar, may get charred on heating to the
dryness.
• Some impurities may remain dissolved in the solution even after filtration.
• On evaporation these contaminate the solid.

38. APPLICATIONS
• Purification of salt that we get from sea water.
• Separation of crystals of alum(phitkari) from impure samples.

39. WATER PURIFICATION SYSTEM IN WATER
WORKS

40. PHYSICAL AND CHEMICAL CHANGES
• The properties that can be observed and specified like colour, hardness, rigidity,
fluidity, density, melting point, boiling point etc. are physical properties.
• The changes in which no new substance is formed, are called physical changes.
• Examples- Freezing of water, Tearing a piece of paper etc.
• Chemical change brings change in the chemical properties of matter and we get
new substances.
• The changes in which new substance is formed, are called chemical changes.
• A chemical change also called a chemical reaction.
• Examples- Rusting of iron, Formation of curd from milk etc.

41. DIFFERENCE
Physical Changes
1. No new substance is formed.
2. It is a temporary change.
3. It is reversible in nature.
4. The mass of a substance does not
change
5. Very little light and energy is usually
absorbed or given out .
Chemical Changes
1. A new substance is formed.
2. It is a permanent change.
3. It is irreversible in nature.
4. The mass of a substance change.
5. A lot of heat or light energy is given
out or absorbed.

42. THANK YOU
BHARAT GURUKUL