Biology Pratical work

  • Created by: Vss2017
  • Created on: 24-11-17 10:49

Qualitative Test's - Show if certian substances are present not amounts.

  • Benedict's test is used to detect Reducing Sugars.

Cannot distinguish between different monosaccharides.

(A REDUCING SUGAR is a suagr which can donate electrons to Benedict's reagent.)

Reducing sugar + Benedict's solution + Heated in a water bath

Colour change- blue, green, yellow, orange, brick red precipitate.

(Non-Reducing Sugars E.G. all monosaccharide sugars and some disaccharide sugars- sucrose)

Non-Reducing sugars can be identified by a negative benedicts test result at first, but when HYDROLYSED , with DILUTE HYDROCHLORIC ACID and heating, then once cooled NEUTRALISE with sodium hydrogencarbonate and test with benedict's solution, it gives a POSITIVE result.


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