User:Physchim62/Titration error

In a titration, the colour change is not exactly at the end point of the reaction, and it is impossible to know how much of the last drop is required to give the stoichiometric quantity of reactant. Together, these two factors constitute the titration error.

The titration error is a systematic error in the measured end-point of a titration. It is inherent in the method, and so cannot be eliminated by performing repeated titrations on the same sample, not even by different analysts using different equipment. The titration error is usually negligible for routine titrations using standard procedures, but must be taken into account for high-precision analyses by titration and in the design of new methods.

There are two components to the titration error:

• Indicator error: the colour change of an indicator may not be exactly at the point of equivalence between the two reactants.
• Last-drop error or half-drop error: the smallest volume that can be measured with a burette is equal to one drop, but it is not known what proportion of the last drop of reagent to be added was needed to reach the equivalence point.

Both of these errors can be reduced by good experimental design. They can be eliminated altogether by using an interpolated endpoint, as in potentiometric or conductometric titrations, but at the expense of an increased Type A measurement uncertainty ("random error").

Volumetric analysis

Main article: Titration

Notes and references

Bibliography

• Miller, J. C.; Miller, J. N. (1988), Statistics for Analytical Chemistry (2nd ed.), Chichester, UK: Ellis Horwood, ISBN 0-7458-0292-3.
• Vogel, Arthur I. (1939), A Textbook of Quantitative Inorganic Analysis, London: Longmans.