Chemistry for NMAT

WHAT IS VOLUMETRIC ANALYSIS?

  • Volumetric Analysis:  Chemical technique that uses the solution as reactants and helps us to find out the quantities of substances reacting t if the concentration of one of the solution is known
  • The principal of volumetric analysis: Principal of volumetric is based on the law of chemical equivalent which states that substances always react in their equivalent proportion
  • Titration: Process of determining the concentration of an unknown solution by finding out the volume of it required to react completely with a known volume of standard solution
  • Alkalimetry: Process of determining the concentration of alkali by neutralizing it with a standard acid solution i.e. acid of known concentration
  • Indicator: A chemical substance that indicates the completion of a chemical reaction by distinct color change. It is a weak organic acid or base that changes their color because of the change in the structure
  • End Point: A point of time during the titration when a reaction is completed that is indicated by the sharp change in the color of the indicator
  • Unknown solution: The solution whose concentration is not known
  • Equivalent Point: The point in a reaction at which an equal number of gram equivalent of reactants react together
  • Standard solution: The solution of known concentration
  • Primary standard solution: The standard solution that is prepared directly by dissolving the calculated mass of a substance into a certain volume of solution. For example, Sodium carbonate
  • Secondary Standard Solution: The solution that is standardized with a primary standard solution. For example, sodium hydroxide

IMPORTANT POINTS ON EQUIVALENT WEIGHT OF CHEMICAL SUBSTANCES

  • Equivalent weight of element = Atomic weight / Valency
  • Equivalent weight of acid = Molecular weight / Basicity
  • Equivalent weight of base = Molecular weight /Acidity

NOTE: Acidity is the number of gram equivalent of acid required to neutralize a mole of base

  • The equivalent weight of oxidizing agent = Molecular weight/ Total change in Oxidation Number
  • Equivalent Weight of Reducing Agent = Molecular Weight/ Total Change in Oxidation Number

CONCENTRATION OF SOLUTION= There is different ways to express the concentration of a solution. Some of them are given below:

  • Normality: Normality of a solution means the number of gram equivalent of the substance dissolved in a liter of its solution. It is denoted by N.

                                          Normality = No. of gram equivalent /Volume of solution in lite

  • Normal solution: Containing one gram equivalent of a substance dissolved in one liter of its solution
  • Seminormal solution: The solution containing half gram equivalent of a substance in one liter of its solution
  • Decinormal Solution: The solution containing one-tenth gram equivalent of a substance dissolved in one liter of its solution
  • Molarity: Number of the mole of a substance dissolved in one liter of its solution. It is denoted by M
  • Molarity = Number of mole of a substance / Volume of a solution in liter
  • Molality: The number of mole of a substance dissolved in one kg o solvent. It is denoted by m

Molality =  No. Sof mole of substance / Mass of solvent in Kg

  • Gram per Litre = Mass of the substance dissolved in one liter of its solution

PERCENTAGE: Percentage of a solution can be expressed in various ways a follows:

  • Percentage by weight (W/W): It is a mass of a substance as indicated by % present in 100 gram of its solution.
  • Percentage by volume (W/V): Mass of a substance  indicated by percent present in 100 ml of its solution
  • Percentage (V/V) : Volume of solute as indicated by % present in 100 ml of its solution
  • Normality factor: The ratio of the mass of substance taken to the mass of the substance to be taken

                         Normality factor (f) = mass of a substance taken / actual substance to be

IMPORTANT FORMULAE ON VOLUMETRIC ANALYSIS

  • Equivalent weight of acid = Molecular weight/ Basicity
  • Equivalent weight of base = Molecular weight / Acidity
  • Equivalent weight of salt = Molecular weight / No. of Positive or Negative Charges
  • Number of gram equivalent = Weight of substance in gram /Equivalent weight in gram
  • Normality = Number of gram equivalent / volume of solution in litre
  • Number of mole = Weight of substance in gram / Molecular weight in gram
  • If volume of gas at  normal temperature and pressure is given,

then  No. of Mole = Volume of gas in liter at normal temperature and pressure / 22.4

  • Molarity = No. of moles / Volume of solution in liter
  • Normality × Equivalent weight = Molarity × Molecular weight
  • Normality of an acid = Molarity × Basicity
  • Normality of Base = Molarity × Acidity
  • Normality of a Salt = Molarity × Total No. of Positive or Negative charges
  • Normality = (gram /litre of solute) / Equivalent weight
  • Molarity = ( gram/litre of solute) molecular weight
  • If percentage of solute is given in a solution, then

Normality = (% of solute × 10) /Equivalent weight of solute