IODINE TEST FOR STARCH The Iodine test is used to test for the presence of starch. Iodine solution — iodine dissolved in an aqueous solution of potassium iodide — reacts with the starch producing a purple black color. The colour can be detected visually with concentrations of iodine as low as 0.00002M at 20°C. However the intensity of the colour decreases with increasing temperature and with the presence of water-miscible‚ organic solvents such as ethanol. Also the test cannot be done at very low
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The intended purpose of radioactive iodine is to eliminate all of the tissue that is over producing the thyroid hormone. However‚ in recent years‚ it has been shown that 10% to 40% of patients who receive radioactive iodine have to receive additional treatment. The experiment used to determine the efficiency of radioactive iodine used adult patients who were not pregnant and did not have thyroid cancer. A total of 325 patients were
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Chemical reaction: C6H8O6 + I2→ 2I + C6H6O6 Ascorbic Acid: C6H8O6 Relative formula mass of C6H8O6= (12.01076) + (1.007948) + (15.99946)= 176.12412 g/mol Convert Iodine lost from mL to dm-3 = Iodine lost in mL1000= Iodine lost in dm-3 Convert Iodine lost (dm-3) to moles (n) by multiplying it with the concentration of Iodine used: n=0.005 Iodine lost in dm-3= mol of C6H8O6 Find the mass (g) of C6H8O6 in 50 mL by using this equation: m (mass)=Mr (Relative formula mass)n (mol) Convert into percentage
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* Tripod * Gauze mat * A large white evaporating dish * Scissors and forceps | * Glass stirring rod * Test tube rack * Test-tube (30mm x 180mm) * Methylated spirits * Iodine solution * 100mL beaker * Soft green leaves * Rubber gloves | Risk Assessment: Risk | Prevention | Iodine Solution stains skin and clothesIt’s harmful with contact with eye or consumed | Wear rubber gloves‚ be careful with solutionDon’t touch eyes‚ keep away from mouth | Methylated spirits
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using starch and iodine? Introduction Amylase is an enzyme found in human saliva and pancreas. It is the digestive enzyme that is needed to breakdown starch molecules. Amylase must be kept at certain conditions to function at its optimum level. This experiment will explore the effect of pH (1‚ 4‚ 7‚ 10‚ and 14) on the function of amylase by using starch and iodine. Usually iodine has a orange-yellow color‚ but iodine and starch react to produce a dark blueblack color‚ so iodine may be used as
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acid (acidified water) Solution of Sodium thiosulfate Granular zinc Iodine crystals Zinc ion and iodine-iodide-triiodide ion in water Solid zinc iodide Mineral oil Silver nitrate Magnesium turnings 3M Hydrochloric acid (HCl) solution 2 boiling tubes 1 large tube (we used a small) Pipet Beakers (to hold tubes) Bunsen burner PART 1 Procedure Get a boiling tube and label it R (reactants). Weigh out 2g of granular zinc and 2 g of iodine crystals and add to boiling tube “R”. Get a large test tube and
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almost perfect circle‚ takes longer to reach max expansion‚ covers more surface area‚ lays flatter on surfaceWater: did not form even circle‚ reached max expansion very quickly‚ formed more of a bubble on surfaceBOTH: Clear and shiny | e) Making iodine in water: potassium iodide (KI)‚ and sodium hypochlorite (bleach‚ NaClO). | KI- ClearNaOCl- ClearWhen combined they solution immediately turned a bright yellow. |
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drops of iodine solution to tube 5. (i) To the remaining liquid in tube 3‚ add about 20 mm Benedict’s solution and place the tube in the boiling water bath for 5 minutes. (j) Pour half the contents of tube 4 (starch and saliva) into tube 6 and then add three drops of iodine to tube 6. (k) Test the remaining liquid in tube 4 with Benedict’s solution as you did in (i). (l) Pour half the contents of tube 7 (starch solution) into tube 8 and test the two samples respectively with iodine as in
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Benedict’s reagent and Iodine stain tests. Benedict’s reagent will react to reducing substances in the solution by oxidizing it and changing the structure of the reducing sugar to form a colored precipitate. The color of this precipitate can be used to determine the concentration of reducing sugars in the substance. If the precipitate is blue no reducing sugars are in the substance. If the precipitate is bluish green‚ green‚ yellow‚ or orange it does contain reducing sugars. Iodine stain will be used
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a titration. Introduction Redox titrations using sodium thiosulphate as a reducing agent is known as iodometric titration since it is used specifically to titrate iodine. The reaction involved is: I2 + 2Na2S2O3 I2 + 2S2O322NaI + Na2S4O6 2I- + S4O62- In this equation I2 has been reduced to I- :2S2O32I2 + 2e S4O62- + 2e 2I- The iodine/thiosulphate titration is a general method for determining the concentration of an oxidising agent solution. A known volume of an oxidising agent is added into an excess
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