Chem - Is matter around us pure ?

• Pure


  Having no adulteration
• For a scientist, most things are actually mixtures of different substances and hence not pure
• Pure substance


  Consists of a single type of particle, all the constituent particles are the same in their chemical nature
• Most of the matter around us exists as mixtures of two or more pure components
• Mixture


  Constituted by more than one kind of pure form of matter
• Mixtures


  • Sea water
  • Minerals
  • Soil
• Homogeneous mixture/solution


  Mixture with uniform composition throughout
• Homogeneous mixtures/solutions


  • Salt dissolved in water
  • Sugar dissolved in water
• Heterogeneous mixture


  Mixture containing physically distinct parts and non-uniform compositions
• Heterogeneous mixtures


  • Sodium chloride and iron filings
  • Salt and sulphur
  • Sand and water
• Forming a mixture


  1. Adding components

  2. Stirring properly

  3. Observing if particles are visible

  4. Observing path of light beam

  5. Observing if particles settle

  6. Filtering the mixture
• Solution


  A homogeneous mixture of two or more substances
• Solutions


  • Lemonade
  • Soda water
• Alloy


  A mixture of two or more metals or a metal and a non-metal, with variable composition
• Alloys


  • Brass (30% zinc, 70% copper)
• Is MATTER AROUND US PURE?
• How do we judge whether milk, ghee, butter, salt, spices, mineral water or juice that we buy from the market are pure?
• Pure substance


  A substance that cannot be separated by physical process into its chemical constituents
• Pure substances


  • Salt
  • Sugar
• Mixture


  Contains more than one pure substance
• Soft drink and soil are not single pure substances
• Whatever the source of a pure substance may be, it will always have the same characteristic properties
• Homogeneous mixture


  Mixture with uniform composition throughout
• Homogeneous mixtures


  • Salt dissolved in water
  • Sugar dissolved in water
• Heterogeneous mixture


  Mixture with physically distinct parts and non-uniform composition
• Heterogeneous mixtures


  • Sodium chloride and iron filings
  • Salt and sulphur
  • Oil and water
• Groups A and B obtained a homogeneous mixture, Groups C and D obtained heterogeneous mixtures
• Solution


  A homogeneous mixture of two or more substances
• Solutions


  • Lemonade
  • Soda water
• Solvent


  The component of the solution that dissolves the other component
• Solute


  The component of the solution that is dissolved in the solvent
• Solutions


  • Sugar in water
  • Iodine in alcohol
  • Carbon dioxide in water
• Properties of a solution

  • Homogeneous mixture
  • Particles smaller than 1 nm in diameter, not visible to the naked eye
  • Particles do not scatter light, path of light not visible
  • Particles cannot be separated by filtration
  • Stable, particles do not settle
• Dilute solution


  Solution with relatively low concentration of solute
• Concentrated solution


  Solution with relatively high concentration of solute
• Saturated solution


  Solution that has dissolved as much solute as it is capable of dissolving at a given temperature
• Unsaturated solution


  Solution with less solute than the saturation level
• Solubility


  The amount of solute present in a saturated solution at a given temperature
• Concentration of a solution

  The amount of solute present in a given amount of solution
• Ways of expressing concentration


  • Mass by mass percentage
  • Mass by volume percentage
  • Volume by volume percentage