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IB Chemistry Lab Design - compare the effect of temperature on the concentrations of Vitamin C and Vitamin A in solution

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Introduction

Research Question: To compare the effect of temperature on the concentrations of Vitamin C and Vitamin A in solution. Research Question: To compare the effect of temperature on the concentrations of Vitamin C and Vitamin A in solution. Background Information: Many researchers claim that the vitamin content in the food we eat decreases as we cook the food, since it is being exposed to high temperatures. This really intrigued me since cooking is one of my hobbies, and I always try and check the nutritional value of meals that I cook. With this in mind, it was quintessential for me to see for myself if these claims hold true. To narrow the scope of the investigation, I chose Vitamins A and C to do this study upon. The claims state that the enzyme in whose form Vitamin C is found, gets denatured (or oxidised) at temperatures over 70°C as well as at low temperatures, in the freezer. Also, studies claim that Vitamin A (in the form of retinol) gets oxidised at high temperatures, during cooking. Once these vitamins get oxidised, they are lost to us. This investigation will compare the effects of high temperature on Vitamin A and Vitamin C solutions. ...read more.

Middle

This can be avoided by adding the same mass of ascorbic acid to the same volume of water while preparing all the sample solutions. Volume of Ascorbic Acid solution The volume of acid solution used for each temperature and each trial should be the same since otherwise it will affect the volume of iodine solution used. Therefore, the volume has to be measured accurately using a pipette for each temperature and trial (each titration). Concentration of starch, potassium iodide and potassium iodate solutions The concentration of any of these solutions will affect the volume of solution titrated during each trial. Thus, it needs to be kept a constant. This can be done by ensuring that equal masses of these reagents are added to equal volumes of water, for all the trials. Final temperature of solution The final temperature of the solution may affect the concentration of the acid in the solution, as rapid heating and cooling can encourage oxidation. Thus, to avoid errors, the solutions will be allowed to rest till they reach room temperature, and only then will they be titrated to calculate concentration. Materials Required: Glassware Item Quantity Least Count Beaker (250 ml) 5 ---- Beaker (500 ml) 3 ---- Pipette (20 ml) ...read more.

Conclusion

Note down the volume of iodine solution used. 1. Re-fill the burette to the 0.0 ml mark. Repeat the titration process 2 more times. Note down these two values for volume of iodine solution used as well. Calculate the average volume used. 1. Check that all the solutions that were heated (or cooled) have reached room temperature, with the help of a thermometer. 1. If they have reached room temperature, repeat the entire titration process (steps 18 – 24) with the other 4 solution (0°C, 30°C, 60°C and 90°C). Ensure that the burette is re-filled to the 0.0 ml mark after each and every titration, and that the pipette is first washed, and then rinsed with the solution that is going to be placed in the conical flask. 1. Use unitary method, to calculate the concentration of Vitamin C in each solution, after heating or cooling, using the concentration of the solution at room temperature (0.002 M) as the known value. Data Collection: Uncertainty of the burette is ±0.05 millilitre. Uncertainty of the weighing scale is ±0.01 grams. S. No. Temperature (°C) Volume of iodine solution used (ml) (±0.05 ml) Average volume of iodine solution used across all three trials (ml) Concentration (mol dm-3) Trial 1 Trial 2 Trial 3 1 R.T.P (control) 0.00200 2 0 3 30 4 60 5 90 | Page ...read more.

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