Reducing sugar plan

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Planning Exercise

Introduction

The aim of the experiment is to test three samples of solution of fresh orange, lemon and grapefruit juice, and distinguish the amount of reducing sugars each one contains and to compare glucose standards.  

        The experiment is going to be conducted in a similar manger to the preliminary experiments in that I am going to add the same amount of glucose solution, the same amount of distilled water and benedict’s solution and then place it all in bath water and begin taking results from there on.

Prediction

I predict that all three of the juices will contain reducing sugars that will reduce the copper ions in the benedict’s solution. The reason for my prediction is that all three of the juices originate from a fruit and will therefore contain the sugar fructose. Fructose is a monosaccharide.  Monosaccharides are single sugar unit’s, they have the general formula, (CH2O)n, because they have a C=O bond in the molecule they can contribute an electron to the copper, and therefore they are reducing sugars, in the process they themselves are oxidised.

Reducing sugar + Cu2+         -         oxidised sugar + Cu+  

 

This C=O bond is known as the anomeric carbon atom, sugars reduce benedict’s solution when the anomeric carbon atom is made available to reduce the copper ions. If a reducing sugar is present then the solution will gradually turn through green, yellow, and orange to brick red as the insoluble copper sulphate forms a precipitate. Through scientific knowledge I therefore predict that all the samples of juice will turn the solution brick red.  However it is difficult to know which one out of the three contains the most sugar, that fact that all of the samples already have a colour, also the species of the fruit will have to be taken into consideration when looking at the results at the end of the experiment.                                                                                                                                                                                                                                                                                              

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Apparatus

The equipment that will be used for the experiment include,

- test tubes, which will contain solutions, I.e. the juices,

- test tube rack

- a syringe, to measure the quantity of solution going in.

- water bath, the solutions are heated in the bath water.

        The solutions used in this experiment will be, 4% glucose solution, distilled water, benedict’s solution and finally fresh orange, lemons and grapefruit.

Method

1. Firstly take four test tubes and label them so that it will be possible to identify one solution from another.

2. Using a syringe transfer ...

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