Titrimetry Flashcards
Titration
A procedure in which one substance (titrant) is carefully added to another (analyte) until complete reaction has occurred
Volumetric Analysis
A technique in which the volume of material needed
to react with the analyte is measured
Titrant
The substance added to the analyte in
a titration (reagent solution)
Analyte
The substance being analyzed
Equivalence point
The point in a titration at which the
quantity of titrant is exactly sufficient for stoichiometric reaction with the analyte
end point
observed equivalence point
An indicator
changes color in response to the change in a
reactant’s concentration
Titration Error
Difference between
end point and equivalence point =
systematic error
back titration
a reagent is added to the
analyte in excess, and then that reagent is titrated to an end point
– Often done to get sharper Endpoint
direct titration
the titrant added slowly to
the analyte until reaching an end point
Before the Equivalence Point
[A] = (Fraction of Titrant Remaining)(M of Analyte)(Original Volume of solution /Total Volume of solution)
At Equivalence Point
[A][T] = Ksp
After the Equivalence Point
[T] = (Original Concentration of Titrant)(Volume of excess Titrant / Total Volume
of Solution)
The less soluble the product
the sharper the curve
around the equivalence point
Argentometric titrations
titration with Ag+
Volhard
colored complex forms at end point
– SCN- with indicator (Fe3+)
Used to determine the amount of Ag+
Fe3+ is the indicator
acidic conditions
Fajans
adsorption of colored indicator on the precipitate at end point
– (Fluorescein)
– Cl- analysis
Adsorption indicators
anionic dyes attracted to
positive charged particles produced
immediately after the EP. Adsoprtion changesthe color of the dye. Color change is the endpoint. Ex. Dichlorofluorescein greenish yellow
in solution to pink when adsorbed on AgCl
Complexation Titrations
are based on the reaction of a metal ion with
a chemical agent to form a metal-ligand complex.
EDTA
Chelate effect
ability of multidentate ligands to form stronger metal
complexes compared to monodentate ligands
Multidentate ligand:
a chelating agent with more than one free
electron pair
Monodentate ligand
a chelating agent with only one pair of free electrons
EDTA complex
becomes less stable as pH decreases
EDTA indicator
Eriochrome Black T Indicator
Metal Ion Indicator
a compound that changes color when it binds to a
metal ion
