Solutions and Colligative Properties

• A solution is a homogeneous mixture of a solute and a solvent.
• A homogeneous mixture is a solution which is uniform throughout. The particles are not separated and are all the same size.
• Solute is the minor component of solution
• Solvent is major component of the solution
• If the solute is a solid and the solvent is a solid an example of the solution is alloy
• if the solute is a liquid and solvent is a solid then example of a solution is Amalgam (sodium amalgam)
• if the solute is a gas and solvent is a solid then example of a solution is H2 on Pd
• if the solute is a solid and solvent is a liquid then example of a solution is glucose + H2O
• if the solute is a liquid and solvent is a liquid then example of a solution is R-OH + H2O
• if the solute is a gas and solvent is a liquid then example of a solution is Carbonated drinks
• if the solute is a solid and solvent is a gas then example of a solution is Camphor in air
• if the solute is a liquid and solvent is a gas then example of a solution is Chloroform in air
• if the solute is a gas and solvent is a gas then example of a solution is air
• Methods to express concentration which are volume based are temperature dependent
• Methods to express concentration which are weight based are temperature independent
• Volume based :

  1. (W/V)%
  2. (V/V)%
  3. Molarity
  4. Normality
  5. Formality
• Weight based:

  1. (W/W)%
  2. molality
  3. mole fraction
  4. ppm
  5. ppb
• Weight by weight percentage is the weight of solute present in 100 g solution

  
• ppm - 10^6
• ppb - 10^9
• Molarity is number of moles per volume in Litres
• molality is the number of moles of solute per one kg solvent
• nf for acids is the number of replaceable H+ ions per molecule (basicity)
• nf for bases is the number of replaceable OH- ions (acidity)
• nf for salts is the total charge present on anion or cation
• nf for oxidants and reductants is the number of electrons lost or gained per molecule
• kMnO4 has n factor 1 in basic medium, 5 in acidic medium and 3 in neutral medium

  Trick = BAN 153
• Gram equivalent weight is the weight of a substance that reacts exactly with 8g of Oxygen or 35.5g of Chlorine or 1g of hydrogen
• GEW is the weight of substance that corresponds to a transaction of 1 mole of electron
• GEW is the weight of one gram equivalent of a substance
• number of gram equivalents = n x nf
• GEW = GMW/nf
• number of gram equivalents = W/GEW
• number of gram equivalents = N x V(L)
• Normality is the number of gram equivalents of solute per 1L solution
• N = M x nf