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internal assessment vitaminC

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Introduction Refer to Biology Handbook page 159 Aim To uncover the effects of heat on the amount of vitamin C in foods Research question What are the relationship between the length of time lime juice is boiled and the concentration of vitamin C in the lime juice sample? Hypothesis The longer the lime juice is boiled, the lower the concentration of vitamin C in the lime juice sample will be. Variables Independent variable: duration of boiling: - 0 min (fresh lime juice ), 10 min, and 1 hour Dependent variables: Concentration of vitamin C in lime juice sample Fixed variables: 1. Type of juice - Lime juice will be used throughout the experiment 2. Volume of DCPIP used in each titration - only 1 cm3 of DCPIP will be used in each titration 3. The person who decide whether the colour change of DCPIP - The same person will decide whether the DCPIP had reduced to colourless solution or not. 4. Environment - the experiments will be conducted at the same place so that the temperature and pressure of surrounding will be constant. ...read more.


0.80 35.40 34.6 2nd 0.30 31.60 31.3 1 hour boiled lime juice 1st 0.50 35.70 35.2 2nd 0.20 34.00 33.8 * Solution is the mixture of glacial acid, respective lemon juice and distilled water. Table 1: volume of solution used in the titration Data Processing * The average volume of titrated juice = * The concentration of ascorbic acid in each juice can be calculated using the following formula; The mass of ascorbic acid equivalent to 1 cm3 of DCPIP = 0.05 mg1 In n cm3 of juice solution = 1 cm3 DCPIP Hence, the volume of lime juice sample titrated contains 0.05 mg of ascorbic acid Therefore, the concentration of ascorbic acid in sample = mg ascorbic acid = X Therefore, concentration of ascorbic acid in pure juice, = Concentration of ascorbic acid in pure juice = 25% X * Uncertainty = % uncertainty of average volume used in titration Juice Average volume used, � 0.10 cm3 Concentration of ascorbic acid, mg cm-3 Fresh lime juice 26.25 0.0476 � 0.4 % Boiled lime juice (10 min) ...read more.


2. Vitamin C, one form of ascorbic acid, can be denatured by high temperature breaking it into simpler molecules. The longer the lime juice is boiled, the higher the amount of vitamin C that will be denatured and thus decreasing the concentration of vitamin C in lime juice. 3. We can relate this result of experiment in our daily life such as cooking. In order for us to get the maximum benefit of eating fruits and vegetables, we should reduce the time of cooking of the fruit or in some cases, just eat them raw so that the amount of vitamins in them is the highest. 4. The function of acetic acid in this experiment is to minimize the acidic effect of ascorbic acid as it can lower the temperature of the solution. Conclusion From the result, the longer we boil the juice sample, the lesser is the content of ascorbic acid in the sample. So, we can conclude that the longer we cook our food, the lesser is the content of vitamin C in them. 1 International Data Standard, July 1980 ?? ?? ?? ?? Zubair Abdur Rahim bin Ahmad M08L Measuring the concentration of vitamin C ...read more.

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