analysis lec

• Volumetric Analysis


  A method that involves the measurement of the volume of a solution of known concentration which is used in order to determine the concentration of the analyte
• Standard Solution


  Also known as Volumetric Analysis
• Titrimetric Analysis


  The concentration of a solution is determined by causing the solution to react with another solution of known concentration

  
• Normal Solution


  Contains gram-equivalent of substance that is dissolved in 1 liter of solution (Normality of the Solution)
• Molar solution


  Contains 1 mol of the substance that is dissolved in 1 liter of solution
• Quantitative analysis


  How much is present in a specific solution
• Volumetric Analysis


  1. A + B = C

  2. Volume
• Gravimetric analysis


  1. A + B = C

  2. Weight
• Volumetric Apparatus


  • Beaker
  • Erlenmeyer
  • Graduated cylinder
• Volumetric Apparatus (made to deliver)

  • Burette
  • Pipette
  • Graduated cylinder
• Types of Burette


  • Mohr Burette - alkalimetry: 1 ml subd
  • Geissler Burette - acidimetry
• Sources of Error in The Use of Volumetric Apparatus

  • Improper cleaning of the apparatus
  • Parallax Error
  • Variation in Temperature
  • Air bubbles that trap
• Standard Solution


  A solution whose concentration is known
• Primary Standard


  A highly purified compound that serves as a reference material in all volumetric methods
• Properties of Primary Standard

  • Chemically Pure
  • Chemically Stable
  • Easily Prepared
  • Water Soluble
  • Reacts stoichiometrically with the sample
  • With fairly high equivalent weight

  
• Secondary Standard


  A compound whose purity has been established by chemical analysis and it would be preserved as the reference material for the titrimetric method of analysis
• Analyte


  The solution whose concentration has to be determined
• Indicator


  A substance that changes color of the solution in response to a chemical change
• Standardization


  A process that is used to determine the concentration of a solution of known concentration by titration
• Equivalent Point


  The point in titration when stoichiometrically different amounts of analyte and titrant react
• Endpoint


  The point in titration where we stop adding the titrant
• Titration error


  The determinate error in titration due to the difference between the endpoint and equivalence point
• Types of Chemical Reaction

  • Neutralization Titration
  • Complexometric Titration
  • Precipitation Titration
  • REDOX Titration

  
• LEORA


  Less Electron Oxidized Reducing Agent
• GEORA


  Gain Electron Reduced Oxidizing Agent
• Theories in the change of color of INDICATORS


  • Physiochemical Theory
  • Organic Theory
  • Colloidal Theory
• Properties used to detect End Points (Volumetric Analysis)

  • Color change
  • Turbidity changes resulting from the formation or disappeared of solid phase
  • Electric conductivity of the solution
  • Electric potential between a pair of electrodes immersed in the solution
  • Temperature of the solution
• Elements of Manual Titration

  • Burette
  • Titrant
  • Analyte
  • Indicator
  • Processor
  • Detector
• Difficulties in Manual Titration

  • Reading the meniscus
  • Filling of burette with titrant
  • Reading the volume of the titrant
  • Determination of end point
  • Standardization of titrant
  • Error in computation
• Automatic Titration


  Involves electrochemical sensing technique
• Applications of Titrimetry in Pharmaceutical Analysis

  • Provide standard pharmacopeial methods for assay of unformulated drugs and excipients
  • Used for standardization of raw materials and intermediates used in drug synthesis in industry
  • Certain specialist titrations, such as the Karl Fischer titration used to estimate water content, are widely used in the pharmaceutical industry
• Types of Titration


  • Direct Titration
  • Indirect Titration
  • Residual/Back Titration
• Direct Titration


  The analyte is reacted with the titrant after rendering its solubility in the titration medium
• Indirect Titration


  The sample is converted to an intermediate product that is titrated with the standard solution
• Residual/Back Titration


  Measured excess of the standard solution is added to the sample to accomplish a desired reaction and the excess is back titrated with a 2nd standard solution
• Reasons for performing back titration

  • When the reaction between the analyte and titrant proceeds slowly
  • When the reaction between titrant and analyte does not give a sharp endpoint with the indicator
  • When the sample or analyte cannot be brought to solution without changing the chemical nature upon which the titration reaction is based
• Acid/Base Titration


  Also known as Neutralization Titration
• Neutralization Reaction


  A solution of an acid is usually added to a solution of a base until the base is exactly neutralized and neither acid nor base exists
• Properties of Acids


  • Taste sour
  • React with some metals to give off hydrogen gas
  • Conduct electricity in solution
• Properties of Bases


  • Taste bitter
  • Feel slippery
  • Dissolve fats and oils