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Estimating the glucose concentration of a solution

Produced by Science & Plants for Schools (SAPS), in this investigation, students look at the concentration of glucose in isotonic sports drinks. This enables students to see if the drinks are, in fact, isotonic with the blood.

In this investigation, students first produce a standard curve by testing glucose solutions of known concentrations. Glucose is a reducing sugar which can decolourise purple potassium permanganate solution. The time taken for the loss of colour from a standardised solution of permanganate is directly related to the concentration of glucose present in solution.

This test, and the corresponding standard curve, can then be used to measure the unknown glucose concentrations in sports drinks.

The investigation is designed for students following a Scottish Highers course but it is equally useful for other post-16 courses in biology. It could also be adapted for younger secondary school students.

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