Vitamin C

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An experiment to investigate the enzyme concentration and rate of reaction

Background
To carry out our experiment we used 3 different types of orange juices, and we also used 0.1% of vitamin C solution. The aim of our experiment was to see how much DCPIP was needed to be added to make the orange juices turn back to the orange colour and the DCPIP to decolourise once the 0.1% of vitamin C was added. DCPIP is a blue dye in its non-reduced form; it becomes colourless when it gains electrons. Vitamin C is an anti – oxidant, this is found mainly in fresh fruit and vegetables. The main use of Vitamin C is that it neutralises free radicals, which can cause damage to cells, including cells in the cardiovascular system

Planning
My aim in this experiment is to investigate how much juice is required to decolourise 1cm3 of 0.1%of DCPIP solution. Prediction
Before I started the investigation I made sure I did a hypothesis so that I would be able to refer back to it in the conclusion at the end. Below is my hypothesis: My hypothesis is that: ‘there will be less’ Don Simon’ juice needed to decolourise the DCPIP, the other juices will require more juice to decolourise the DCPIP’ Fair Test

I will have to make sure that I will be carrying out a fair test. This is to ensure that anything affecting the amount needed to decolourise the DCPIP is due to what I have changed (independent variable) and nothing else. Below I have listed the independent variables as well as those factors which should be kept the same.

Independent Variable:
* The Juices
* Amount of Juice added to the DCPIP
Dependent Variable:
* The amount of DCPIP put in the test tube
* 1% of DCPIP
* 0.1% of vitamin C solution
Fixed Variables:
* The volume of DCPIP poured into the test tube
* Keeping a fixed volume of the DCPIP ensures that the decolourisation of the DCPIP is only because of the amount of juice added and not the different amount of DCPIP that is present * Concentration of DCPIP solution

* Different concentrations can affect how long it takes to decolourise, therefore it is important that there is nothing else making it less concentrated. * Concentration of Vitamin C solution

* The concentration of this can affect how much DCPIP is needed to make it colourless The experiment should also be repeated a number of time from which an average will be calculated. This is to ensure that the results are accurate and reliable.

The method
The method we used to carry out this experiment and the equipment we used is shown below; I also included any faults with the method when we carried out the experiment this is all shown below: Equipment and chemicals needed:

* 1% of DCPIP solution
* 0.1% vitamin C solution
* A range of fruit juices
* Test tubes
* Test tube rack
* Syringe
STAGE| PROCEDURE| PURPOSE| ANY FAULTS/LIMITATIONS?|
1| Pipette 1cm3 of 1% DCPIP solution into the test tubes| Provide a clear sight into the experiment at hand. Therefore it makes it easier to establish the decolourisation of the DCPIP.| N/A| 2| Using a pipette or burette, add 0.1% vitamin C solution drop by drop to the DCPIP solution. After adding the drops shake the tube gently | Allows the solution to react with the vitamin C. And therefore resulting in more accurate results| Using a burette would have been more accurate. Also doing the experiment on a bigger scale would also allow any room for accuracy for the results collected| 3| Continue to add drops of the vitamin C solution until the blue colour of the DCPIP has disappeared. | Measure how much vitamin C solution was needed to decolourise the DCPIP| At this point we made sure that the solution was absolutely colourless which was correct, however later we did not do the same thing for the orange juices and therefore we were not able to collect accurate results. | 4| Record the exact amount of the vitamin C solution that was...
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