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

Research QuestionTo compare the effect of temperature on the densenesss of Vitamin C and Vitamin A in root.Background InformationM any researchers birdsong that the vitamin content in the food we eat decreases as we cook the food, since it is creation exposed to high temperatures. This re exclusivelyy intrigued me since cooking is one of my hobbies, and I ever so 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 probe, 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 denaturized (or oxidize) at temperatures over 70C as well as at low temperatures, in the freezer. Also, studies claim that Vitamin A (in the form of vitamin A1) gets oxidised at high temperatures, during cooking. Once these vitamins get oxidised, they are lost to us. This investigation go forth compare the effects of hi gh temperature on Vitamin A and Vitamin C consequences.http//chemmovies.unl.edu/chemistry/small weighing machine/SSGifs/SS054Ascorbic.gifThe ascorbic stifling enzyme gets denatured at high temperatures because the tertiary coordinate of the protein, which the enzyme is made up of, unravels, ca apply the active site of the enzyme to veer in shape. This leads to the substrate being unable to fit into the active site, and we say that the enzyme is denatured. This denaturing provide take place at extremes of pH too.The Vitamin A (retinol) gets oxidised because, at high temperatures, it reacts with oxygen in the air to form a carboxylic sulfurous (retinoic virulent).In the laboratory, ascorbic acid found in fruits and vegetables basin be simulated by imparting ascorbic acid crystals to urine, to form a mildly vitriolic theme. This antecedent can also be apply as the threadbare base during titration to find concentration of ascorbic acid. To simulate Vitamin A, we can sim ply fit retinol to water to form a metre firmness.HypothesisAt higher temperatures, both the concentration of Vitamin C and Vitamin A can be expected to decrease. However, I expect the decrease to be greater in the case of the Vitamin C solution since (having protein-like properties) it is more sensitive to extremes of temperature. Also, the alcoholic drink retinol has a high boiling point, so I believe that it allow be more resistant to oxidation too.VariablesIndependent Variablewhy and How it is ChangedTemperature to which the Vitamin C/A solution is heatThe factor whose effect is being studied on the concentration of Vitamin C/A in a solution is the temperature the solution is heated to. Therefore, the temperature is the independent variable. In order to change the temperature, comprise quantities of the same Vitamin C/A solution are heated to different temperatures. The different temperatures taken are 30C, 50C, 70C and 90C. As a control, one solution is placed at inh abit temperature. A thermometer is utilize to measure the temperature of the solution. Investigation at each temperature will be paralleled 3 times, to ensure reliability. underage VariableWhy and How it is RecordedConcentration of Vitamin C/A in solution (in mol dm-3), after exposure to temperatureThe effect of temperature on the concentration of Vitamin C/A in a solution is being studied, wherefore the concentration is the dependent variable. As the temperature moves further away from room temperature (above or below) the concentration of Vitamin C/A in the solution should decrease collectible to denaturing or oxidation. The concentration of Vitamin C is calculated by doing an iodin titration. A stiffen solution is comeed to a standard Vitamin C solution which is the titrant. Into this, a solution of honey oil iodide and potassium iodate is titrated till a blue colorise is obtained (end point). This is repeated thrice. The average leger of iodine solution used is calcul ated, and carve up by the concentration of Vitamin C.Then, the solutions of unknown concentrations are titrated and unitary method is used to calculate their concentrations. The concentration of Vitamin A is calculated utilize a oxidation-reduction titration. This is done by making a solution of acid dichromate, potassium iodide and starch. This is titrated against a solution of sodium thiosulfate of known concentration. The volume of thiosulfate used is noted. Then, the Vitamin A solutions are added to a similar solution of dichromate, KI and starch, and titration is carried out with thiosulfate. For any 1 less mole of thiosulfate used there is 0.25 mole of alcohol in the sample (according to the chemical equations) which was tested.Controlled VariableWhy and How it is MaintainedpH of Vitamin solutionExtremes of pH can also lead to the denaturing of enzymes, so if pH changes it will interfere with the results, potentially giving inaccurate results. Thus, the pH involve to be unbroken a constant. This can be done by adding a few drops of acidic buffer to the initial solution.Presence of AntioxidantsAntioxidants including salts such as sodium chloride tend to protect ascorbic acid from being oxidised, and so their presence may lead to inaccurate results. Thus, they need to be eliminated. This can be done by using distilled water (without any salts) duration preparing the solution of ascorbic acid.Head Space Present in SystemThe ascorbic acid gets denatured because of oxidation by air. Thus, if the volume of air present in the system changes, the results will also change invariably. To prevent this, the amount of conduce space present in the system must be kept constant. This can be done by placing a lid on top of the beaker in which the acid solution is heated.Initial Concentration of Ascorbic dosage solutionIf the initial concentration of ascorbic acid in the solution is different, accordingly the terminal concentration will also be affected. 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 savage solutionThe 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 metrical accurately using a pipet for each temperature and trial (each titration).Concentration of starch, potassium iodide and potassium iodate solutionsThe 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 solutionThe final temperature of the solution may affect the concentration of the acid in the solution, as rapid heating system 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.Chemicals1. L-ascorbic acid 3.52 g to make 1 dm3 of 0.002 M solution of acid1. Glucose 50 g to add to acid solution, to simulate fruit juice1. Potassium Iodide 10.0 g to make 1 dm3 iodine solution1. Potassium Iodate 0.536 g to make 1 dm3 iodine solution1. Starch (soluble) 0.25 g to make 50 ml of 0.5% starch solution1. 3.00 M Sulphuric Acid 60 ml to add to iodine solution1. Distilled Water To make all the solutions and washing roughly other Materials1. Weighing Scale1. Bunsen Burner1. Tripod Stand1. Wire Gauze1. plaster and Pestle1. Pipette Filler1. Lid (for beaker) 41. ThermometerProcedurePreparing Ascorbic Acid Solution of concentration 0.002 M1. foot planetary house 3.52 g of L-ascorbic acid using the weighing scale and the weighing boat (which has to be completely dry).1. clothe the weighed crystals in the mortar and use the pestle to crush the crystals into a alright powder, to assistant with dissolving it in water.1. Place the powdered acid into a viosterol ml beaker and add a little distilled water to interrupt the acid. Use the glass rod to stir.1. Once it seems that the acid has fully dissolved, add some more water to the solution, to ensure that all the acid has very dissolved. Then, transfer the solution into the 1000 ml standard flask using a process funnel and the glass rod.1. clean the beaker with water and effuse into standard flask, to bring any remaining solution. Repeat this process 3 times.1. Wash the funnel and the glass rod, letting the water run into the standard flask.1. Make up the solution to the 1000 ml mark. Place the hoopla and concoction the solution thoroughly. Transfer approximately 500 ml of this solution to the 500 ml beaker, for ease of use.Preparing the 0.5 % starch solution1. Measure 0.25 g of starch using the weighing scale and weighing boat.1. Bring 50 ml of distilled water nearly to a boil, and then add the measured quantity of starch powder to it. Allow to cool.Preparing the Iodine Solution1. Measure 10.0 g of potassium iodide and 0.536 g of potassium iodate using the weighing scale and weighing boat. Transfer this to a 500 ml beaker.1. Dissolve the solids in approximately 400 ml of distilled water. Stir using the glass rod, to aid in dissolving. fetch the 60 ml of 3.00 M sulphuric acid to the solution at this point.1. Once it seems that the solids have fully dissolved, add some more water to the solution, to ensure that all of it has actually dissolved. Then, transfer the solution into a 1000 ml standard flask, using a washed funnel and the glass rod.1. Wash the beaker with water and pour into standard flask, to remove any remaining solution. Repeat this process 3 times.1. Wash the funnel and the glass rod, letting the water run into the standard flask.1. Make up the solution to the 1000 ml mark. Place the stopper and mix the solution thoroughly. Transfer app roximately 500 ml of this solution to a 500 ml beaker, for ease of use.Titration Set-up and Final Steps1. Transfer 65 ml of Vitamin C solution each into 5, 250 ml beakers.1. Keep one of the containers in a trough containing melting ice (0C). Keep one at room temperature (as a control + standard solution). Heat the other terzetto to 30C, 60C and 90C respectively. Ensure that all the beakers are covered with a lid during heating or cooling.1. Wash the pipette, first using tap water and then distilled water. Rinse the pipette thoroughly with the Vitamin C solution at room temperature.1. Use a pipette to transfer 20 ml of the Vitamin C solution, at room temperature, into a conical flask. This is the standard solution (and the control) since its concentration is known (0.002 M).1. Add 10 drops of the starch solution to the conical flask. Swirl the contents to mix properly.1. Wash the burette with tap water followed by distilled water. Then, rinse the burette with the iodine solution.1. Fill the burette with iodine solution till the 0.0 ml mark.1. Titrate the iodine solution into the conical flask, swirling the conical flask at all times. The end point is reached when a blue colour is obtained that persists even after 20 seconds of swirling. tonicity 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 (0C, 30C, 60C and 90C). 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.