The titrimetric determination of the concentration of sodium hydroxide

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The titrimetric determination of the concentration of sodium hydroxide 29.1.2010

Abstract

Sodium hydroxide is a base often used in titrimetric analysis of drugs. Its concentration is required to be volumetric standard (VS). This means that the exact concentration must be determined by titration before it is used. The “volumetric standard” is defined by the British Pharmacopoeia (BP).

“Ascertain the exact concentration immediately before use in the following manner. Titrate 20ml of the solution with 0.1M hydrochloric acid VS using the indicator prescribed in the assay in which the solution is to be used”

In the BP, standardised solutions are written in italics e.g. 0.1M sodium hydroxide VS .

Key Words

Burette: a long vessel with a tap at the bottom which is used to measure accurately the volume of a solution added. The scale can be read to an accuracy of half a division e.g. to 0.05 cm3.

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Bulb Pipette:  used to deliver an accurate volume of a solution.  This can be 10cm3 or 25 cm3.

Conical flask:  used to hold chemicals and to make chemicals, substances can be stirred and swirled without the risk of spilling and reduces the loss of the evaporation due to the narrow neck.

Methyl Orange Indicator:  a pH indicator frequently used in titrations. It is often chosen to be used in titrations because of its clear colour change.

Titration: The technique of titration is used to find out accurately how much of a chemical substance is dissolved in a given volume of a ...

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