The sensitivity of the Benedict's Test-Investigation

Authors Avatar

The sensitivity of the Benedict’s Test-Investigation

Aim

In this investigation, we will be attempting to find the lowest concentration of glucose that Benedict’s can detect.

Prediction

I predict that that the 10% glucose solution will have the darkest colour dark after testing for reducing sugars whereas the 0.001% glucose solution will have the lightest colour. This is because as the percentage of glucose is increased the darker the colour will become meaning that there is more glucose present. I have predicted this after finding out some information about the Benedict’s test. The Benedict’s solution contains a weak solution of copper II sulphate. Reducing sugars can reduce this to a precipitate of brick red copper I oxide.

Equipment list

10% glucose solution                 Benedict’s solution

Distilled water                           Wax pencil

10cm3 graduated pipette            10cm3 measuring cylinder

5cm3 syringe                              Teat pipettes x2

5 boiling tubes and rack            5 cuvettes and holder

Colorimeter                               Boiling water bath

Procedure

1) Label 5 boiling tubes 1 to 5 with a wax pencil near the top of each tube.

2) Pipette 10cm3 of 10% glucose solution into tube 1.

3) Transfer 1cm3 of this solution from tube 1 to tube 2. Using the measuring cylinder add distilled water s          as to prepare, in tube 2, a 1% glucose solution. Mix well.

Join now!

4) Using firstly 1cm3 of the solution from tube 2, go on to prepare three more glucose solutions systematically: 0.1% (tube 4) and 0.001% (tube 5).

5) Finally, adjust so that all five tubes contain an equal volume of liquid.

6) Using the syringe add 5cm3 of Benedict’s solution to each tube.

7) Transfer all five tubes to the boiling water bath provided for exactly three minutes.

8) Remove and return to the rack.

9) Make a subjective comparison of the colours in each tube by observation. You can use a scale of ‘+’ to ‘+++++’ to record the depth of colour, from lightest to darkest.

...

This is a preview of the whole essay