Titrations Flashcards
(39 cards)
refers to the use of the analytical technique referred to as the titration
Titrimetric analysis
small increments of a reagent solution are added until the reaction is observed to be complete.
titration
include a group of quantitative procedures based on determining the quantity of a reagent of known concentration that is required to react completely with the analyte
Titration Methods
reagent may be in the form of
a) a standard solution of a chemical substance or
b) an electric current of known magnitude
Various Titrimetric Methods
Volumetric Titrimetry - VOLUME
Gravimetric or Weight Titrimetry - MASS
Coulometric Titrimetry - ELECTRIC CURRENT
Various Titrimetric Methods
measures the volume
of a solution of known concentration that is
needed to react completely with the analyte
refers to the analytical procedure where the volume of the reagent needed to react completely with the analyte is measured.
Limitation: Requires
the use of a buret with
high precision
Volumetric Titrimetry
Various Titrimetric Methods
measures the mass of the solution of known concentration that is needed to react completely with the analyte
Limitation: Requires the use of a sensitive analytical balance
Gravimetric or Weight Titrimetry
Various Titrimetric Methods
is a type of titrimetry in which the quantity of charge in coulombs required to complete a reaction with the analyte is measured.
Limitation: Applicable to RedOx Reactions
Coulometric Titrimetry
Set-up for Volumetric Titrimetry
Buret
Buret Clamp
Iron Stand
Conical Flask or Erlenmeyer Flask
must be in the dissolved state
and is contained in an Erlenmeyer flask or
conical flask
analyte
The solution added in small and precise increments is called a
titrant, T
The titrant solution is
delivered through a
buret
of a titration cannot be
determined experimentally because it is a theoretical stage
stage in a titration when the amount of added standard reagent is equivalent to the amount of analyte.
The stage when an equivalent or stoichiometric amount of the titrant has been added is called the
equivalence point
the stage when the reaction is observed to be complete
is the stage in a titration when a physical change occurs that is associated with the condition of chemical equivalence. 4-20
end point
types of Endpoint
Graphic Endpoint
Specific Compound Formers
Colored Titrants/Analytes
Nonspecific, Equilibrium-dependent Compounds
what point occurs at the steepest portion of the graph
equivalence point
Are added to the analyte solution to give an observable physical change (the end point) at or near the equivalence point.
INDICATORS
Methyl orange ph of color change
3.1 red to 4.4 yellow
titration error
The difference in volume or mass between the equivalence point and the end point is the
Is a highly purified compound that serves as a reference material in all volumetric and mass titrimetric methods
PRIMARY STANDARD
REQUIREMENTS OF A
PRIMARY STANDARD
- high purity
- atmospheric stability
- absence of hydrate water
- modest cost
- reasonable solubility in the titration medium
- reasonably large molar mass
when exposed to the atmosphere, form an aqueous solution by absorbing water vapor
Deliquescent substances
when exposed to the atmosphere, do not absorb water vapor but spontaneously release moisture
Efflorescent substances
when exposed to the atmosphere, can absorb water vapor, but they do not form an aqueous solution
Hygroscopic substances
