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