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My aim is to design an experiment to compare quantitatively orange fruit, grapefruit and lemon fruit, with respect to the amount of glucose they contain. I will endeavour to make the experiment as fair as possible and aim to minimise the amount of errors.

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Introduction

Aim: My aim is to design an experiment to compare quantitatively orange fruit, grapefruit and lemon fruit, with respect to the amount of glucose they contain. I will endeavour to make the experiment as fair as possible and aim to minimise the amount of errors. I have been given 4% of glucose solution, benedict's solution and distilled water to find out the concentration of glucose of these three juices; orange, lemon, and grapefruit. The method of serial dilution has to be done to work out the concentration; this is because the concentration of glucose is far too concentrated. A dilution factor has to be worked out; I will be using a dilution factor of 5, which means the amount of glucose and the percentage of glucose will always divide by 2 as the dilution solution carries on. Theory Orange, lemon and grapefruit are all fruits which contain carbohydrates which include reducing sugars. Glucose is a hexose sugar, which is a monosaccharide with six carbon atoms in each of its molecules. Benedict's solution is a deep-blue alkaline solution used to test for the presence of 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) ...read more.

Middle

The solutions should be labelled correctly and the lids of the solutions should are placed on the right bottles and should be secured tightly on The water bath is set at a very high temperature so caution must be taken to avoid any accidents from occurring. Removing and placing anything from the water bath must be taken very seriously and with great care, this will prevent any burns and scaling. Apparatus * 4% glucose solution * Colorimeter, * cuvettes, * Water bath, * Test tube rack, * Test tube, * Distilled water. * 10ml graduated pipette * 25 ml of Benedict's solution * Water Bath * Coloured pencil * Thermometer * Juices, apple, orange, grapefruit. Choice Of Apparatus Item What is it used for Reason for choice Colorimeter Instruments for the analysis of coloured solutions. Most accurate way for this procedure. Cuvettes Hold the solution, which will be placed in the colorimeter. 10ml graduated pipette An apparatus to remove and insert a solution. It is accurate Test tube To hold the solutions in. Most suitable apparatus to hold solutions Test tube rack Hold test tubes in place. Keeps the test tubes upright and organised 25 ml of Benedict's solution A biochemical test which shows the presence of a reducing sugar Test for glucose Distilled water Used to dilute the solution Water Bath 1000C Most accurate way to keep temperature desired the same. ...read more.

Conclusion

It is very important to read of the pipette as accurately as possible and to make sure that the reading is taken from the bottom of the meniscus. It will be necessary to make sure the equipment is clean to get concordant results. Some of the equipment will need to be washed out with a particular solution. For instance when washing out the cuvette you must wash it out with the solution that you will be using next, as if you washed it out with the distilled water this would effect the dilution concentration and therefore would affect the results. Table Of Results Apple Juice Test tube Glucose ml Distilled water ml Glucose % Colour Transmission Glucose Concentration 1 10 - 4 2 5 5 2 3 2.5 7.5 1 4 1.25 8.75 0.5 5 0.6 (0.625) 9.4 (9.375) 0.25 6 0.3 (0.3125) 9.7 (9.6875) 0.125 Grapefruit Juice Test tube Glucose ml Distilled water ml Glucose % Colour Transmission Glucose Concentration 1 10 - 4 2 5 5 2 3 2.5 7.5 1 4 1.25 8.75 0.5 5 0.6 (0.625) 9.4 (9.375) 0.25 6 0.3 (0.3125) 9.7 (9.6875) 0.125 Orange Juice Test tube Glucose ml Distilled water ml Glucose % Colour Transmission Glucose Concentration 1 10 - 4 2 5 5 2 3 2.5 7.5 1 4 1.25 8.75 0.5 5 0.6 (0.625) 9.4 (9.375) 0.25 ...read more.

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