Hanna Instruments HI 904 - Manual (Page 177)

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TITRATION THEORY
End point
The point where a titration is stopped because a physical change in the solution has
indicated a completed titration. Titration end points typically coincide with the equivalence
point. A fixed value end point (pH or mV), can be used as well. The titration will stop
at the desired point regardless if the titration is complete.
Equivalence point
The point where the quantity of titrant is stoichiometrically equal to the quantity of
analyte.
Formal
The theoretical number of equivalents per liter of the solution. It is used in solutions
where the exact concentration of a species may be affected by the other ions present,
therefore the stated concentration by not be exactly correct.
Gravimetric Analysis
A quantitative determination of an analyte based on the mass of the solid.
Indicator Electrode
An electrode that responds to the species of interest. The electrode potential is
proportional to the concentration or activity of that ion in the solution being measured.
Indicators
Chemical indicators are typically organic dyes that change form under different physically
conditions, causing a color change that can be seen by an analyst. Typically used in
manual titrations. Chemical indicators have been replaced with electrometric indicators,
which are used with automatic titrators.
Inflection Point
The point on a titration curve were the second derivative curve changes signs.
Ion Selective Electrode (ISE)
An electrode that responds to a specific ion, the electrode potential is proportional to
the concentration or activity of that ion in the solution being measured.
Karl Fischer Titration
A titration that uses a chemical reaction that is specific for determining water.
Manual Titration
A titration that is carried out by hand, the analyst must add the appropriate amount of
titrant, determine the end point and calculate the results.
Molar
The concentration of a solute in a solution.
Mole (mol)
A quantity of a chemical species. The molecular weight of a substance in grams is
equal to the mass of one mole of the substance. One mole is equal to 6.022 x 10
23
atoms or molecules.
Monochromator
A device that allows only a narrow range of wavelengths to pass though it by separating
the light into different wavelengths.
Multiple End Point Titration
A titration that reacts multiple species in solution sequentially using the same titrant.
The concentration of each analyte can be determined from their respective end points.
Nernst Equation
The fundamental equation relating cell voltage to the concentration of a solution.