IS MATTER AROUND US PURE?

Anything which occupies space and has mass is called matter. Matter can be divided into two categories. 
(i) Pure Substance: It consists of single types of particles that are the same in their chemical nature. 
(ii) Mixtures: Mixture consists of two or more particles. 

MIXTURE AND ITS TYPES

The mixture consists of more than one kind of pure substances which can be separated by physical method. It has two types (i) Homogeneous mixture (ii) Heterogeneous mixture

(i)HOMOGENEOUS MIXTURE

A mixture is said to be homogeneous if all the components of the mixture are uniformly mixed and there are no boundaries of separation between them. Ex: Sugar in water, etc.

(ii)HETEROGENEOUS MIXTURE

A mixture is said to be homogeneous if all the A mixture is said to be heterogeneous if all the components of the mixture are not uniformly mixed and there are visible boundaries of separation between them. Ex: Water and sand, Air etc.components of the mixture are uniformly mixed and there are no boundaries of separation between them. Ex: Sugar in water, etc.

SOLUTION AND ITS PROPERTIES

A solution is a homogeneous mixture of two or more substances. Ex: Lemonade, soda water etc. A solution has two types:(i) Solvent (ii) Solute

(i)SOLVENT

The component of the solution that dissolves the other component in it (usually the component present in larger amount) is called the solvent.

(ii)SOLUTE

The component of the solution that is dissolved in the solvent (usually present in lesser quantity) is called the solute.

PROPERTIES OF SOLUTION

1. A solution is a homogeneous mixture. 
2. The particles of a solution are smaller than 1 nm (10-9) in diameter which cannot be seen by naked eyes. 
3. They do not scatter a beam of light passing through the solution that is they don’t show tyndall effect. So, the path of light is not visible in a solution. 
4. The solute particles cannot be separated from the mixture by the process of filtration. 
5. The solution is stable and solute particles do not settle down when left undisturbed. 

CONCENTRATION OF A SOLUTION

  • The concentration of a solution is the amount of solute present in a given amount (mass or volume) of solution. Also, the amount of solute dissolved in a given mass or volume of solvent is called concentration of solution. 
  • Concentration of solution = Amount of solute/Amount of solvent or Amount of solute/Amount of solution (Here, amount means mass or volume). 

(i) SATURATED SOLUTION

When no more amount of solute can be dissolved in a solution at a given temperature, it is called a saturated solution.

(ii)UNSATURATED SOLUTION

When more amount of solute can be dissolved in a solution at a given temperature, it is called a saturated solution.

(ii)SOLUBILITY

The amount of the solute present in the saturated solution at the given temperature is called its solubility.

TWO METHODS OF FINDING CONCENTRATION OF A SOLUTION

(i) Mass by mass percentage of a solution = (Mass of solute/Mass of solution) ×100 
(ii) Mass by volume percentage of a solution = (Mass of solute/Volume of solution) ×100 

SUSPENSION AND ITS PROPERTIES

A suspension is a heterogeneous mixture in which the the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Ex: Chalk in water, smoke in the air

PROPERTIES OF SUSPENSION

1. It is a heterogeneous mixture. 
2. Particles of a suspension are visible to the naked eye. 
3. Size of the particles is greater than 100 nm. 
4. It is unstable mixture. Solute settles down at the bottom over period of time. 
5. If the solution is passed through filter paper, solute and solvent gets separated. 
6. It scatters light when light is passed through the solution i.e. it shows Tyndall effect. 

COLLOIDAL SOLUTION

Colloid solution is heterogeneous mixture in which the size of particles lies between the true solutions and suspensions. Colloidal particles can easily scatter a beam of visible light. This phenomenon is called Tyndall effect.

PROPERTIES OF COLLOIDAL SOLUTION

1. The particles of colloid can’t be seen by naked eyes individually. 
2. It is a heterogeneous mixture and thus solute and solvent can’t be separated by filter paper. 
3. Size of particles is smaller than suspensions but greater than solutions (1 nm to 100 nm). 
4. It is a stable mixture. Particles do not settle down at the bottom over a period of time. 
5. They do not settle down when left undisturbed which means colloid is quite stable. 

SOME COMMON EXAMPLES OF COLLOIDS

SEPARATION OF COMPONENTS OF MIXTURE

Different methods of separation are used to get individual components from mixture. Heterogeneous mixtures can be separated into their respective constituents by simple physical methods like handpicking, sieving, filtration etc.

SUBMLIMATION

  • This process is used to separate mixtures that contain a sublimable volatile component from a non-sublimable impurity.
  • Sublimation is process where a substance directly changes from solid to gaseous state on heating.
  • Ammonium chloride, camphor, naphthalene and anthracene are some examples which can sublime.

CHROMATOGRAPHY

  • Used to separate those solutes which dissolve in the same solvent.
  • Used for sepration of colours.
  • The colours which are more soluble in water rises faster and get colours get separated into layers.

APPLICATIONS

  • To separate colours in a dye
  • To separate pigments from natural colours
  • To separate drugs from blood.

DISTILLATION

  •  Used for separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points.
  •  Mixture of acetone and water is separated by this method.

FRACTIONAL DISTILLATION

  • Fractional distillation is used to separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K.
  • Air is a homogeneous mixture and can be separated into its components by fractional distillation.
  • The air is compressed by increasing the pressure and is then cooled by decreasing the temperature to get liquid air.
  • The liquid air is warm-up slowly in a fractional distillation column, where gases get separated at different heights depending upon their boiling points.
  •  It used to separate a gas from the air.

CRYSTALLIZATION

  •  Used to remove impurities from solid and purify it.
  • It separates a pure solid from mixture in the form of crystals. This process is used in purification of salt from sea water, separation of crystals of alum from impure samples.
  • It is better method than evaporation because:
    (i) Solids decompose or some, like sugar, may get charred on heating to dryness.
    (ii) Some impurities may remain dissolved in the solution even after filtration. On evaporation these contaminate the solid.

PHYSICS AND CHEMICAL CHANGES

  • The process which brings about changes in physical properties and no new substances are formed are physical changes.
  • The common physical changes are changes in colour, hardness, rigidity, fluidity, density, melting point, boiling point etc.
  • The process in which new substances are formed and chemical properties of substances get changed are chemical changes.
  • Some chemical properties are odour, inflammability etc.

PHYSICAL CHANGES

  • It brings about change in physical properties such as physical state, shape, size etc.
  • No changes in chemical compositions are observed.
  • It is reversible.
  • No new substance is formed.

CHEMICAL CHANGES

  • It brings about changes in chemical properties.
  • Changes in chemical properties are observed.
  • It is irreversible that means permanent
  • New substance is formed.

TYPES OF PURE SUBSTANCES

The pure substance is divided in two types on the basis of their chemical composition:
(i) Elements (ii) Compounds 

(i) ELEMENTS

  •  According to Antoine Laurent Lavoisier, an element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.
  • It is divided into three types which are metals, non-metals and metalloids.

PROPERTIES OF METALS

(i) They have a lustre (shine). 
(ii) They have silvery-grey or golden-yellow colour. 
(iii) They conduct heat and electricity. 
(iv) They are ductile (can be drawn into wires). 
(v) They are malleable (can be hammered into thin sheets). 
(vi) They are sonorous (make a ringing sound when hit). 
• Examples of metals are gold, silver, copper, iron, sodium, potassium etc. 
• Mercury is the only metal that is liquid at room temperature. 

PROPERTIES OF NON-METALS

(i) They display a variety of colours. 
(ii) They are poor conductors of heat and electricity. 
(iii) They are not lustrous, sonorous or malleable. 
Examples of non-metals are hydrogen, oxygen, iodine, carbon (coal, coke), bromine, chlorine etc. 

METALLOIDS

Elements having intermediate properties between those of metals and non-metals are called metalloids. Examples are boron, silicon, germanium etc.

(ii) COMPOUNDS

A compound is a substance composed of two or more elements, chemically combined in a fixed proportion.

DIFFERENCE BETWEEN MIXTURE AND COMPOUND

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