Back to Lesson

• Mixture: Two or more substances mixed with each other and can be distinctly identified is called as mixture. E.g. Mixture of wheat and stone, mixture of rice flakes and raisins.
• Homogeneous mixture: A mixture in which particles of substances are uniformly distributed is called as homogeneous mixture. Homogeneous mixtures can have variable composition. E.g. Mixture of salt and water.
• Heterogeneous mixture: A mixture in which particles of substances are non uniformly distributed is called as heterogeneous mixture. E.g. Mixture of water and stones.
• Solution: A solution is a homogeneous mixture of two or more substances. Solution can be solid solution, liquid solution and gaseous solution.
• Components of solution:
  • Solute: Substance in a solution present in less quantity is called as solute.
  • Solvent: Substance in a solution present in large quantity is called as solvent.
  • E.g. Salt is solute and water is solvent in salty solution.
• Concentration of solution: It is amount of solute present in the solution.
  • Dilute solution: Solute is present in small quantity in a solution.
  • Concentration of solution: Solute is present in large quantity in solution.
  • Formula to calculate concentration of solution:
    • Mass by mass percentage of solution = (mass of solute / mass of solution) × 100
    • Mass by volume percentage of solution = (mass of solute / volume of solution) × 100
  • Saturated solution: Solution dissolves solute to its dissolving capacity.
  • Unsaturated solution: Amount of solute in a solution less than the dissolving capacity of solution is called as unsaturated solution.
  • Solubility of solution: It is the amount of solute present in the saturated solution.
• Suspension: It is a heterogeneous mixture in which particle of solute do not dissolve and remain suspended within the solution.
• Colloidal solution: Solution is heterogeneous, in which particle size is larger than solution and smaller than suspension.
• Component of colloid:
  • Dispersed phase: Contains solute particles or dispersed particles
  • Dispersion medium: Dispersed phase is suspended in dispersion medium

  

• Comparison between properties of solution, colloid and suspension:

	Solution	Colloid	Suspension
Particle size	Very small	Larger than solution but smaller than suspension	Larger
Visibility of particle	Not visible by naked eye	Not visible by naked eye	Visible by naked eye
Tyndall effect	Do not scatter beam of light	Scatters beam of light	Scatters beam of light
Sedimentation	Particles do not settle down if kept undisturbed	Particles do not settle down if kept undisturbed	Particles settle down if kept undisturbed
Separation	Particles cannot be separated by filtration	Particles cannot be separated by filtration but can be separated by centrifugation	Particles are separated by filtration

• Tyndall effect: It is the scattering of light due to solute particles in colloids or in suspension.
• Techniques for separation of components of mixture:

Name	Process	Application(s)
Evaporation	Separates volatile component from non volatile component. Volatile component evaporates leaving non volatile component	Separation of dye from ink
Centrifugation	Separates fine solute particles which from liquid which are not separated through filtration	Used in dairy for separation of butter from cream Used in laboratories for blood and urine test
Separating funnel	Separates liquids which do not mix with each other	Separation of oil and water
Sublimation	Separate sublimable volatile impurity from non sublimable volatile impurity	Separation of camphor from salt
Chromatography	Components of mixture are separated using filter paper and solvent. More soluble component rises high on filter paper.	Separation of colors from dye
Distillation	Separates mixture of two or more liquids	Separation of ethanol and water
Fractional distillation	Separates mixture of liquids having less than 25K difference in boiling point.	Separation of liquids from crude oil

• Separation of components of air: Air is homogeneous mixture of different types of gases. Gases from air are separated by fractional distillation. Steps for separating of air



• Crystallisation: Crystals of pure solid is obtained from the liquid by heating and cooling.
• Pure substances: Pure substances are classified as element and compounds. Elements are further classified into metals, nonmetals and metalloids.
• Metals vs nonmetals:

Metals	Nonmetals
Have lustre	Do not have lustre
Good conductors of heat and electricity	Bad conductors of heat and electricity
Are ductile, malleable and sonorous	Are not ductile, malleable and sonorous
Are hard	Are brittle
Are solid in state except mercury	Are in solid, liquid and gaseous state
E.g. Iron, Gold, Silver, Sodium, Copper,etc	E.g. Carbon, Hydrogen, Bromine, Oxygen, etc

• Metalloids: Show properties in between metals and nonmetals. E.g. Germanium, Silicon, Arsenic, etc.
• Compound: It is formed when two or more elements chemically combine with each other, and forms new substance with new properties.
• Distinguish between mixtures and compounds:

Mixtures	Compounds
Elements or compounds are mixed together to form a mixture. No new compound is formed.	Elements react with each other to form new compounds with new properties.
Mixtures have variable composition	Compounds have fixed proportion
Mixture show original properties of constituents present in it.	Compound do not show original properties of substance of which it is composed.
Constituents of mixture are separated by physical methods	Constituents of compounds are separated by chemical process
Example : Mixture of Copper filings and sulphur, salt and sand, etc.	Example : Copper Sulphate, Carbon Disulphide, etc.

• Overlook of mixtures and pure substances: