1. (A) outline how you would compare the reducing sugar concentration in apple juice and orange juice. (B) consider the fact that the two liquids have different colours. How would you account for this when using a colorimeter.
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- Thread Starter
- 27-10-2017 19:43
- Official Rep
- 29-10-2017 20:16
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- 29-10-2017 20:20
A) Benedict’s solution reacts with reducing sugars on heating and reduces the Cu(II) ion to Cu(I) producing a precipitate of red copper oxide. The resulting colour change depends on the type and concentration of sugar, so this test has been used semi-quantitatively to indicate approximate concentrations.
B) An alternative version of Benedict's reagent for quantitative testing contains potassium thyocyanate and does not form red copper oxide. Instead the presence of reducing sugar is measured by the loss of the blue colour of copper sulphate and a white precipitate is formed which will settle out or can be removed by filtration before colorimetric determination of the filrate.