Then you titrate the iodine remaining with sodium thiosulfate solution using starch indicator. Because you know how much iodine was produced from iodate(V) and iodide and you have found by titration how much is left over you can calculate how much iodine must have reacted with the ascorbic acid. First you will need to analyse a solution of ascorbic acid with a known composition. By doing
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iodide ions I-‚ using a ’clock’ reaction. Principle The equation for reduction of S2O82- by I- is: S2O82- + 2I- → 2SO42- + I2 The formation of iodine is ’monitored’ by small & known amount of thiosulphate ions‚ S2O32-: 2S2O32- + I2 → S4O62- + 2I- Once the reactants are mixed‚ the stop-watch is started. At the time when all of the thiosulphate is reacted‚ any free iodine produced will turn starch
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39. The Viscosity of Liquids After studying the present lecture‚ you will be able to Define viscosity and viscosity coefficient Outline the method to measure viscosity using Ostwald viscometer Determine the average molecular weight of a polymer Determine the surface concentration of 1-butanol in aqueous solution Measure the distribution coefficient of a solute betweenn two solvents 39.1 Introduction Viscosity‚ one of the transport properties‚ arises because of intermolecular attractive and
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The effect of Sodium Chloride (NaCl) salt concentration on osmosis in potato cells The movement of substances in plant cells involves many processes and systems‚ all of which may affect the plant bio-chemically and physically‚ and one of these processes is osmosis. Osmosis is the flow of water through a semi-permeable membrane of a cell moving from an area of higher water potential to an area of lower water potential until reaching equilibrium known as isotonic. Before reaching the point of being
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INVESTIGATING THE EFFECT OF TEMPERATURE ON THE RATE OF ENZYME ACTIVITY. To investigate the effect that temperature has on enzyme activity I am going to use the enzyme amylase‚ which is used as a biological catalyst to break down starch‚ which cannot pass through the gut wall due to the size of the molecules‚ into smaller ones. Amylase is a carbohydrase‚ which converts starch to simple sugars in the Salivary Glands. Three features of all enzymes are: They are always proteins. They are specific
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Test tube holder 2% starch solution 6 boiling tubes labelled 1 to 6 1% lead nitrate solution 6 test tubes labelled A to E‚ ( F) Dimple tiles 5 test tubes labelled A1‚ B2‚ C3‚ D4‚ E5‚ (F6) 5 ml syringe 1% Amylase solution 4 dropping pipettes Stop clock Firstly‚ in each of the boiling tubes place 8 ml of 2% starch solution using the syringe. Then in each of the test tubes labelled A to F add 1ml of 1% Amylase solution. In the remaining 6 test tubes add the different concentrations of the lead nitrate
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is starch present. I will use a stop clock to measure the time taken. Control variables This is what I will keep the same in the experiment so the test will be fair. I will keep the volume of starch and amylase the same in each part of the experiment. The test tubes will stay in the water for five minutes‚ and three drops of iodine will go into each test tube of starch. Apparatus 5 Beakers 10 Test tubes 5 Thermometers Starch Amylase Ice Iodine Kettle Warm water Dropping pipette
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this experiment was to determine the reaction order of the oxidation of iodine with respect to persulphate (part 1) and iodine (part 2). For part 1 of the experiment‚ this was done by titrating a solution of 50 cm3 of diluted 0.0225M persulphate and 250 cm3 of 0.4M potassium iodine against a 50 cm3 solution of 0.01 M solidum thiosulphate‚ using 3 ml of 2% starch as an indicator. For part 2‚ a solution of 25cm3 of iodine and persulphate‚ and 25 cm3 of 0.04M potassium chloride was titrated against
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water (100 C). We repeated the same thing for the boiled amylase. We then checked at five minutes to see if the starch had been digested by the amylase. We did this by putting a little of each of the six samples into a spotting tile. We then added iodine solution to this to see if starch was present or not. I could tell if starch was present or not because if the solution went orange it meant that there was no starch present‚ so all the starch had been digested‚ if the solution went blue/black it
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reaction may also be known as the ‘Iodine Clock Reaction.’ The rate of the reaction will be measured by timing the reaction between Hydrogen Peroxide‚ Potassium iodide‚ and Sodium Thiosulphate. Sodium Thiosulphate is used as a delaying mechanism as the reaction between the two main reactants is too rapid to measure. The Sodium Thiosulphate will react with the Iodine [III] ions (the product) first and when the all the Sodium Thiosulphate has reacted‚ then the remaining Iodine ions will form a blue-black
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