Practical investigations
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Why is it better to use back titration in the analysis of acetylsalicylic acid in aspirin samples?
Corrie writes ....
In the direct titration of aspirin samples with alkali there is always the possibility that the amount of hydrolysis of the aspirin that occurs as a side reaction during the titration may be sufficient to affect the accuracy of the final reading. For this reason it is usually suggested that direct titration is carried out quickly and that the mixture is cooled in ice, so that any hydrolysis is minimised.
Back-titration avoids this complication as the aspirin is completely hydrolysed before it is titrated.
Risk assessment
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updated: 17 August 2007
