DESIGNVitamin C is an essential nutrient, with many important functions beneficial to the human body. It is important in the growth and repair of tissues, bones and teeth, and is essential in producing collagen,and in healing wounds. It helps in the absorption of iron,is an antioxidant and also increases immunity.However, although being so vital to the human body, it is water soluble, so body is unable to store it, and any excess is excreted out from the body. Therefore, in order to maintain healthy levels, daily intake of food containing this Vitamin is necessary. Vitamin C is easily destroyed by cooking, and is also sensitive to heat and light so it is best if consumed through raw fruits and vegetables which are a good sources of Vitamin C. An excellent source of Vitamin C are oranges, and since this Vitamin cannot be stored yet is needed daily, it can becomes difficult to maintain healthy levels. My goal is to find out if the ripeness of the orange has an effect on it’s Vitamin C content and at what stage of ripeness are these levels the highest so I can eat these oranges and benefit from them at their prime time. The question this investigation aim to answer is; Research Question : At what stage does the ripeness of the orange have the highest amount of vitamin C content?One of the reasons for conducting this investigation is because oranges are a snack frequently eaten at my household, it being my family’s favourite snack as well as an affordable source of Vitamin C, so finding out about the ripeness of oranges and its correlation to high Vitamin C content will become a deciding factor for us to either buy oranges on everyday basis or to buy in bulk at sale price.The idea of this investigation also came to me when I read about the benefits of having high levels of Vitamin C plays a big role in fighting off colds and viruses. By finding an answer to my above research question will help me better maintain the high amounts of Vitamin C so I can boost my immunity and become more resistant to colds.This is highly needed in today’s world as the chance of falling sick due to incoming cold or viruses is very high.Iron absorption in the body is enhanced by Vitamin C as well. Iron is needed to make hemoglobin, and its deficiency can lead to Anemia which leads to low oxygen in your body,which can be very serious. Vitamin C helps the body to absorb both plant and meat iron which in turn help makes hemoglobin and maintain healthy red blood cells. This research will be a big help to me as I do not like to eat meat and poultry as much as vegetables, so eating these high content Vitamin C oranges can help me stay healthy by promoting iron absorption from vegetables sources. Hypothesis I predict that the least ripe orange will have the most vitamin C as it is the most recently harvested and thereby have less time for the vitamin C to diminish. It is also has a more sour taste compared to a ripened orange which I think is an indicator of high Vitamin C content, since vitamin C is an ascorbic acid and acids tend to taste more sour.MethodologyVitamin C is also known as ascorbic acid (C6H8O6?) which are commonly found in citric fruits such as oranges. The aim of this exploration is to calculate the amount of ascorbic acid (Vitamin C) at different stages of an oranges maturity. To make sure we only find the ascorbic acid in the fruit, excluding the citric acid, we need to conduct an Oxidation/Reduction (Redox) Titration. Iodide (I2) is a chemical that creates a redox reaction with ascorbic acids, but instead of directly reacting these chemicals, we will use potassium iodate (KIO3). The chemical equation of this reaction is: IO3- (aq) + 5I-(aq) +6H+ (aq) 3I2 (aq) +3H2O (l) Once the I2 is formed inside the erlenmeyer flask, the I2oxidizes the ascorbic acid to dehydroascorbic acid according to the following chemical equation:C6H8O6+I2C6H8O6 + 2I-+2H+After all the ascorbic acid is consumed by the I2 (and has reached and equivalence point), the excess iodine creates a starch ( I3) and will SHOW a blue colour, which tells us the neutralization has been completed.The two chemical equations that represent this reaction are: I2 (aq) + I-(aq) I3-(aq)I3-(aq)+starch starch-I3- Throughout this lab the data I will be collecting is the amount of iodate that is added into the flask to neutralize the ascorbic acid. From this I will be able to calculate how much vitamin C is in each sample of orange.The independent variable in this investigation is the different stages of maturity the orange is at, this will be measured in days starting after I have bought the orange from the supermarket. The dependant variable is the amount of vitamin C found in the oranges measured in milligrams which will change according to the ripeness of the orange.A control variable in this experiment would be the type of orange used throughout the experiment. I am using large Navel Oranges and making sure they are kept under the same conditions as one another to avoid my data being skewed. Another control variable would be in keeping the concentration and volume of each solution used consistent, such as the base (KIO3), the vitamin C concentrate or the starch solution. To control this variable I am using lab equipment with high degrees of accuracy such as a pipette to ensure every measurement is constant.I will be conducting 5 trial for each of the stages of the orange’s ripeness, first being the day the orange is bought then,5 days after it is bought and lastly, 10 days after it’s bought. I am measuring specifically from the days after I have bought the orange from the grocery store instead of when the orange is brought from the farm because when applying this to my own life, I will need to know the time I should eat the orange after buying it as opposed to the time I should eat it after the orange has been harvested.Materials:Large Navel Oranges (3)80 ml Beaker (3)200 ml Beaker 50ml Beaker (2)Erlenmeyer FlaskClamp StandBuretBuret ClampJuicerStrainerPipettePumpDropperKIO3solution (15 ml)Starch (5 ml)HCL (15 ml)Distilled Water (150 ml)Procedure: Use the juicer to squeeze the orange,Once the orange has been squeezed, strain the juice to get rid of the pulp.Make 50 ml of base solution by diluting 12.5 ml of KIO3solution with 37.5ml of distilled water to create a concentration of 0.002M.Create a 3% starch solution by mixing 1.5g of 100% starch and 48.5ml of distilled water. This solution must be freshly made.Create the Vitamin C concentrate by mixing 5 ml of orange juice, 10 ml of HCL, 50 ml of distilled water and 1.5ml of both the starch solution and KIO3.Set up clamp stand and adjust the buret and buret clamp onto it.Fill the buret with 50ml of the diluted KIO3solution.Fill 125ml Erlenmeyer Flask with the vitamin C concentrate.Place the Erlenmeyer Flask under the buret, record the volume the buret indicates initial level and turn the switch slightly to start the drops.Watch the Vitamin C concentrate until it reaches a blue green colour, once the concentrate has been fully neutralized turn the switch off and record the volume the buret indicates once again at the end.Repeat steps 7-9 for each trial and at different stages of the orange’s ripenessBefore starting this lab, I was made aware of the safety precautions,in order to keep me and my classmates safe. The foremost safety precaution for this lab was to make sure to wear protective gear like, chemical safety goggles and to avoid eye and skin contact. Although titrating Vitamin C from orange juice was very safe and no ethical concerns were involved in this part of the experiment, however precautions had to be taken with the iodine solution as this can be a harmful chemical. The concentration of 0.002 M iodine solution is not acutely hazardous to health but it is still highly important to follow safety procedures. Also safety precautions included tying long hair back not wearing any loose clothing, open shoes and knowing where the safety equipment was kept.Also safety tips included not to taste or drink any lab materials especially since iodine solutions are toxic and harmful if inhaled or swallowed. Also it is an important safety measure to work in a well ventilated area and to clean up immediately if there were any spills, and to dispose off the contents at the end of the experiment in an approved manner and tidy up the workplace. Failure to follow these safety precaution could lead to burns to the skin or irritation even blindness in the eyes, in severe cases. DATA & OBSERVATIONTable 1.1 – Raw Quantitative Data of Amount of Iodate added to Vitamin C concentrateOrange at Different StagesTrail #Initial Volume of Iodate (mL 0.05)Final Volume of Iodate (mL 0.05)Amount of Iodate added (mL0.05)15024.425.625026.323.7 0 day old orange340192144015.224.854017.622.4Average Amount of IO3-23.5 ml 0.1Table 1.2 – Raw Quantitative Data of Amount of Iodate added to Vitamin C concentrateOrange at Different StagesTrail #Initial Volume of Iodate (mL0.05)Final Volume of Iodate (mL0.05)Amount of Iodate added (mL0.05)65034.415.6734.416.4185 day old orange84025.214.8925.27.817.4103014.815.2Average Amount of IO3-16.2 ml 0.1Table 1.3 – Raw Quantitative Data of Amount of Iodate added to Vitamin C concentrateOrange at Different StagesTrail #Initial Volume of Iodate (mL0.05)Final Volume of Iodate (mL0.05)Amount of Iodate added (mL0.05)113122.58.51222.512.51010 day old orange13188.8.131.5243020.39.71520.39.810.5Average Amount of IO3-10.02 ml 0.1Sample Calculation : Finding Average amount of IO3-for the 0 Day Old OrangeCalculating the AverageAverage amount of Iodate added = 25.6+23.7+21+24.8+22.45 = 23.5 mLAbsolute uncertainty for sumUnc = (x)2+(y)2 = (0.05)2+(0.05)2+(0.05)2+(0.05)2+(0.05)2 = 0.1?The average amount of Iodate added is 23.5 ml 0.1Calculations for the Data Tables 1.2 and 1.3 were done similarly.Table 2.1 – Qualitative Observations TrialObservationsAll Trials- The solution started with light yellow colour and gradually changed to a dark greenish blue colour-Iodate was a amber colour-Drops of Iodate fell at a constant rate1-5-Orange was firm-Citrus smell coming from the juice sample6-10-Orange that was juiced had a small bruise-Citrus smell coming from the juice sample11-15-The orange that was juiced had a slight odor-Orange that was was juiced was much softerDATA ANALYSISTable 3.1 – Processed DataStage of Orange’s MaturityAmount of Vitamin C ( mg /100g)Percentage Uncertainty0 Day Old Orange49.10.021%5 Day Old Orange33.820.9%10 Day Old Orange20.920.9%Sample Calculations for 0 Day Old OrangeTo start the process of calculating the amount of vitamin C for each stage of the orange, I will first need to calculate the number of moles of IO3- using the n=cv formula. I will substitute c with the concentration of my iodate solution and substitute vwith the average volume of IO3-that was added for the first stage of the orange.Number of moles of Iodate (IO3-) Let ni represent the number of moles of IO3- ni=cvni=0.002 0.0235ni=0.000047 mol?There are 0.000047 moles of Iodate Relative Uncertainty for Iodateunc = ((0.10.0235) 100)unc = 4.3%Now that I have calculated the the number of moles of iodate, I am able to use molar ratios to find the number of moles of iodide, which in turn will help me calculate the number of moles of ascorbic acid found in the sample of orange juice. I am using the molar ratios in accordance to the chemical formula representing the redox reaction that took place in the lab being:IO3- (aq) + 5I-(aq) +6H+ (aq) 3I2 (aq) +3H2O (l) The molar ratio between the iodate and the iodide is 1:3. Number of moles of iodide (I2)Let nii represent the number of moles of I2 nii=nimolar rationii=0.000047 31nii=0.000141 mol?There are 0.000141 moles of IodideTo calculate the number of moles of ascorbic acid I am using the molar ratios IN ACCORDANCE to the equation representing the oxidation of ascorbic acid being, C6H8O6+I2C6H6O6 + 2I-+2H+The molar ratio between the iodate and ascorbic acid is 1:1Number of moles of ascorbic acid (C6H6O6)Let na represent the number of moles of C6H6O6 na=niimolar rationa=0.000141 11na=0.000141 mol?There are 0.000141 moles of ascorbic acid After calculating the number of moles of ascorbic acid found in the sample of orange juice, I then will convert the value into milligrams using the m=nmmformula. I will substitute the nwith the number of moles of ascorbic acid calculated above and substitute mmwith the molar mass of C6H6O6it being, 174.108 g/mol.Convert moles of ascorbic acid to mass (mg)m=nmmm=0.000141 mol 174.108 g/molm=24.549228 milligrams ?There are 24.5 mg/50 ml of vitamin C in the 0 day old orange juice sampleRelative Uncertainty of molar massUncertainty of carbon = 0.00046Uncertainty of hydrogen = 0.000040Uncertainty of oxygen = 0.000170.00046 +0.000040 +0.00017 = 0.00067 amuunc = ((0.00067174.108) 100)unc = 0.00038%Since my orange juice sample was 50 ml, to find how much is vitamin C is found in 100g of juice, I will multiply the value by two. This is done because the literature values that are provided are also given in terms of 100 g of juice and this will make comparing them easier.Convert to per 100g24.549228mg/50ml 2=49.098456 mg/100g?There are 49.1 mg/100g of vitamin C in the 0 day old orange juice sampleRelative Uncertainty of Massuncertainty of iodate = 4.3%uncertainty of molar mass= 0.00038%unc = (uncertainty of iodate) + (uncertainty of molar mass)unc = 4.3 +0.00038 unc = 4.30038% Absolute Uncertaintyunc = (vitamin C value) (relative uncertainty of mass)unc =0.0490984564.30038unc = 0.021%The calculations for the rest of the values in data table 3.1 were done similarly.After calculating and processing my data, it is important for me to also compare my results to the literature values from another study. These values will indicate to me how accurately my experiment was conducted and how reliable my data is, which is very important to know since i am applying these results to my daily life.Table 4.1 – Literature Values of Vitamin C Content Orange StageVitamin C Content (mg/100g)Unripe51.93 Half-Ripe48.77Ripe43.55These values of Vitamin C content were obtained from a study published on Open Science named “Effect of Ripening Stage on Vitamin C Content in Selected Fruits” Percentage Error of Unripe OrangesPercentage Error =(Literature Value – Experimental Yield)Experimental Yield 100Percentage Error =(51.93 – 49.1)49.1 100 =5.76374745 % =5.8%Table 5.1 – Percentage ErrorStage of OrangePercentage Error0 day old orange5.8%5 day old orange44.29%10 day old orange108.37%CONCLUSIONThe goal of this investigation was to answer the question, At what stage does the ripeness of the orange have the highest amount of vitamin C content? After calculating the results, I have found that the least ripe orange has the most amount of vitamin C of the three stages as it had 49.1 mg/100g 5.8%. This means that the best time for me to eat the orange is the day it is bought from the store and therefore will change my shopping habits accordingly. I can conclude that the Vitamin C content in oranges diminishes over time, proving my hypothesis correct. EVALUATIONOne strength of this investigation is that I ensured all my measurements were done as accurately as possible. I took great caution when recording measurements such as when reading the number on the buret I would measure the meniscus level of the liquid at eye level to get exact readings. I also took great precaution in being accurate when creating the vitamin C concentrate and diluting the KIO3as I knew these measurements play a big role in skewing my data.As in any lab there were also a few limitations in this investigation, one limitation would be the assumption that no other factors played a part in the decrease of Vitamin C overtime. There are many elements that could have affected the vitamin C content in the oranges, such as exposure to air while the lab would take place or the change in temperature when I took the oranges outside in cold weather while coming back and forth from school. Another factor could be the use of pesticides on the oranges that were tested. This factor does not skew the the accuracy of my lab but it could affect the overall results, not allowing me to implement this research in my daily life as it could possibly mean that I would not garner the same results when using this information outside of this lab. Another limitation of this investigation is depending on my eyesight to detect change in colour signalling the end point, there is a possibility I may have over or under titrated some trials as I was not able to see the exact difference in colour or stop at the exact endpoint which could play a part in skewing my results.Some steps I could take to improve the reliability and accuracy of this lab would be to use a pH probe to help indicate the endpoint of titrations as opposed to using an indicator which signals the endpoint using colour. By using a pH probe I would be able to record the exact point when the acid is neutralized and be able to calculate more accurate results. To receive better results I could also measure the vitamin C of the oranges more frequently and could also calculate at what point does the orange start to lose it’s vitamin C at a faster rate.Possible extensions of this lab include investigating further into the factors that I discussed before, such as the use of pesticides, I could compare organic and inorganic oranges to check if the pesticides have an effect on the Vitamin C content. I also learnt that Vitamin C is very unstable, and oxidizes fast when exposed to air,so I could as a next step test if Vitamin C content is affected by the of oxygen in the air. I could also explore if temperature changes the vitamin C content when it is stored at room temperature or when refrigerated. Also i would be interested in following the rate of decrease of vitamin C when cooked. These extensions can help me better understand how vitamin C is affected and find better ways to consume the amount of vitamin C needed by my body, just as this investigation has done for me.