I expect to find that lemon will have the least sugar content and the melon to have the most. I predict that Melon juice would have the a more red precipitate colour solution followed by grape juice with a slight brownish yellow precipitate, then will be lemon juice with the lightest colour of these precipitate.
Method:
In order for this experiment to work we had to be extremely accurate with measurements. This is why we chose to use a graduated pipette and a different one each time.
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 boiling water for 8 minutes – timed using stopwatch
- Removed test tubes and allowed them to cool
- Compared the colour produced in the fruit juice to the colour standards then estimated the concentration of the reducing sugar.
Table to show the findings of my experiment: the colours of the fruit juices in comparison to the glucose concentrations
Conclusion
As the table shows the experiment was a failure. 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.
