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To estimate the sugar content of different fruit solutions.

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Introduction

Quantitative Estimation of Sugars Aim: to estimate the sugar content of different fruit solutions. Hypothesis: Lemon, Melon and Grape are all fruits which contain carbohydrates which include reducing sugars. Glucose is a hexose sugar. Benedict's solution is a deep-blue alkaline solution used to test for the aldehyde functional group, CHO - which are present in reducing sugars. Benedict's solution changes colour when a reducing sugar is present because of a chemical reaction, which reduces the Copper II sulphate (which is soluble) to copper I oxide, which is insoluble and produces a precipitate. The benedict's solution changes colour from blue to green, yellow, orange, brown and finally red - as the amount of sugar increases. ...read more.

Middle

Glucose concentrations: 0.5 %, 1%, 2%, 5%, 10%, 15%, 20% Fruit Juices: Grape, Melon, Lemon and Solution X * Used a 1 cm3 graduated Pipette to put 0.3 cm3 of the different glucose concentrations into separate test tubes and labelled them with the correct percentage. * To each test tube added 5cm3 of Benedicts Reagent solution * Placed test tubes in boiling water for 8 minutes - timed using stopwatch * Removed test tubes and allowed them to cool * Used a 1 cm3 graduated Pipette to put 0.3 cm3 of each fruit juice solutions into separate test tubes labelled with the name of the fruit juice. * Used a 5cm3 Graduated pipette to put 5cm3 of Benedicts Reagent solution into each test tubes * Placed test tubes in ...read more.

Conclusion

The glucose concentrations did not come out with the right colour spectrum therefore it was impossible to estimate the concentrations of the fruit juices. From our findings it would appear that grape has a similar concentration to 5% glucose although the colour matches were very uncertain. The experiment neither proves my hypothesis correct or incorrect. Errors could have been made at any stage in the experiment. Possibility of contamination or inaccurate measuring using the graduated pipettes. It is not possible to pin point exactly what went wrong and at what stage of the experiment. The experiment could be improved by producing a good colour spectrum, by being as accurate as possible. The experiment could be repeated to produce a wider range of results. ...read more.

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3 star(s)

***
This is a clear description of the investigation but would be improved by greater attention to detail and more complete explanations. The analysis is relatively weak.

Marked by teacher Adam Roberts 20/08/2013

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