...Chemistry 221, Section 001 Iodine Iodine is a nonmetallic element of the halogen group with an atomic number of 53. The name iodine is from a Greek word: ioediës, meaning violet or purple because of the elements vapor. The natural element was discovered in 1811 by a French man name Bernard Courtois approximately around the time when France was at war (Swain). In a time of horror and death, there was a shortage of wood ashes used for obtaining potassium nitrate. As an alternative source of potassium, big companies and manufacturers turned towards cheap soda kep made from ashes of seaweeds (Swain). Bernard owned one of these plantations; he soon recognized a beautiful violet vapor that condensed with crystals from the seaweed. He spent time afterwards investigating, slowly feeding his curiosity with trials, he tested its reactions with ammonia, the mixture concluded to form a fulminating powder (Swain). Bernard was a successful businessman that had no intentions to changing the world; he was a curious businessman with a mind to feed. Although the birth of Iodine was from Bernard, he proposed his colleagues to continue his experiments with new tests: Clément a chemist professor, GayLussac, Chaptal, Ampère and Humphry Davy in 1813. Through years of further research they discovered iodine was a indecomposable substance with similar chemical properties to chlorine, it as well formed new acids with hydrogen (Medicine net). By 1820, the discovery of iodine Pham 2 ...
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...Elements such as fluorine, chlorine, bromine, iodine, and astatine belong to the halogen group. Iodine is a chemical element of the periodic table with the symbol I and atomic number 53. Iodine has 53 protons and 53 electrons and 78 neutrons. Iodine was discovered in 1811 by the French chemist Barnard Courtois. He was extracting sodium and potassium from seaweed ashes. He accidentally added too much of sulfuric acid (H2SO4) then a violet colored cloud erupted from the mass.The gas condensed on metal objects in the room, creating solid iodine. The name, iodine comes from the Greek word "iodes" meaning Iodine is a nonmetallic, nearly black solid at room temperature and has a glittering crystalline appearance. Iodine has a moderate vapor pressure at room temperature and is a deep violet vapor that is irritating to the eyes, nose, and throat....
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...After it was first discovered in 1886 by Hans Heinrich Landolt, the iodine clock reaction has become one of the most used classroom experiments for demonstrating kinetics (SuperchargedScience, 2018). A clock reaction is a reaction where one of the chemical species (clock chemical) starts off with a low concentration and then has a rapid increase which can then lead to a dramatic colour change (UnitverityNottingham, 1999). The iodine clock works by using iodine as the clock chemical that then reacts with clear starch to produce a deep blue colour. For the Landolt chemical clock in two clear liquids are mixed with one containing KIO3 and the other NaHSO4 they then follow the following chemical reactions. Equation 1 is known as the rate determining...
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...21. Create another iodine-blank sample following steps 12-16 22. Insert a tip on the 50μL micropipette 22. Take 50μL of the previously prepared 1% starch solution and deposit that into a test tube 23. Place the test tube in the vortexer 24. Pour the starch/iodine/ distilled water solution into a cuvette 25. Using a tissue (kleenex/ kimwipe) wipe the surface of the cuvette down 26. Remove the previous sample and insert the new one in 27. Record the new absorbance reading, this is the maximum, remove the sample from the spectrophotometer. Now we have the minimum and the maximum absorbances set for this lab, we have set the range. Creating 6 iodine-blank samples with 50μL of 1% starch 28. Create 6 iodine-blank samples following steps 12-16...
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...find the distribution of molecular Iodine, I2, as the solute between two immiscible liquid phases, water and a hexane solution. The average values obtained for (I2) = 6.11E-06 M, (I-) = 0.1097, (I3-) = 2.82E-04. The results that were found in this experiment show an inaccuracy. This may have been due to the third run in the titration of the Iodine in Hexanes. This inaccuracy is represented on the graph. There should be no variation with the concentration shown. Unfortunately, due to there being only three trials completed there can be no certainty as to which trail is the least inaccurate. I. Introduction The purpose of this experiment was to measure the chemical equilibrium in solution of a typical homogeneous equilibrium in aqueous solution. The equilibrium that is to be observed is that which occurs when Iodine, I2, is dissolved in aqueous potassium iodide (KI). The equilibrium constant, Kc, for each run was found using; Kc = (I3-) (I2w) (I-) (1) The method involves the use of two immiscible liquid phases, aqueous and hexane solution. To determination of I2 present at equilibrium in the aqueous solution use is made of the heterogeneous solutions of hexanes and water. It is observed that the presence of I2 concentration in aqueous solution is very small. This is due to the fact that I2 is nonpolar and is attracted to the nonpolar hexanes. Although, some iodine will still be found in aqueous solution. The total iodine...
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...solution. Unlike diffusion, osmosis requires ATP to move the particles across the membrane. Hypothesis: In both experiments diffusion and osmosis will occur between the solutions. In experiment 1A the tube of glucose/starch will absorb the iodine solution in the cup. In experiment 1B the tube of distilled water will lose weight, and the tube of glucose will gain weight. The purpose of the experiments is to differentiate which test was diffusion and which was osmosis. Materials: Experiment 1A: Plastic Cup, Plastic Pipet, Iodine-Potassium Iodide, Deionized Water, Glucose Paper Strip Experiment 1B: (3) 15 cm pieces of Dialysis Tubing, beaker, 15 cm piece of white thread, 80% Glucose, 2% Starch, Plastic cup, 10% glucose, 15 cm blue thread, distilled water, 15 cm red thread, 20% glucose Procedure Experiment 1A: First cut a 15-cm length of dialysis tubing. Place the dialysis tubing in a beaker of distilled water and allow it to remain in the beaker for 1 minute. Open the dialysis tube by rolling it in between thumb and index finger. Seal one end of the dialysis tube by tightly twisting and tying a knot at one end, approximately 2 cm from the end. Shake excess water from the tube. Using a plastic pipet, place 20 drops of iodine-potassium iodide in a cup. Fill it with Deionized water to within 2 cm of the top. Obtain a glucose test paper strip. Dip the strip into the cup and remove it. The strip will...
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...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 solution of acidified potassium iodide. The reaction will release iodine:Example: (a) With KMnO4 2MnO4- + 16H+ + 10I(b) With KIO3 IO3- + 5I+ 6H+ 3I2 + 3H2O 2Mn2+ + 5I2 + 8H2O The iodine that is released is titrated against a standard thiosulphate solution. From the stoichiometry of the reaction, the amount of iodine can be determined and from this, the concentration of the oxidising agent which released the iodine, can be calculated. In an iodometric titration, a starch solution is used as an indicator as it can absorb the iodine that is released. This absorption will cause the solution to change to a dark blue colour. When this dark blue solution is titrated with the standardised thiosulphate solution, iodine will react with the thiosulphate solution. When all the iodine has reacted with the thiosulphate solution, the dark blue colour will disappear. So, the end point of the titration is when the dark blue colour disappears. Iodine is usually dissolved in water by adding an excess of KI so that KI3 which has similar properties to iodine is formed. I2 + KI I3- + 2e KI3 3I- Oxidising...
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...Winkler test for dissolved oxygen The Winkler test is used to determine the concentration of dissolved oxygen in water samples. Dissolved oxygen (D.O.) is widely used in water quality studies and routine operation of water reclamation facilities. An excess of manganese(II) salt, iodide (I–) and hydroxide (OH–) ions is added to a water sample causing a white precipitate of Mn(OH)2 to form. This precipitate is then oxidized by the dissolved oxygen in the water sample into a brown manganese precipitate. In the next step, a strong acid (either hydrochloric acid or sulfuric acid) is added to acidify the solution. The brown precipitate then converts the iodide ion (I–) to iodine. The amount of dissolved oxygen is directly proportional to the titration of iodine with athiosulfate solution.[1] Today, the method is effectively used as its colorimetric modification, where the trivalent manganese produced on acidifying the brown suspension is directly reacted with EDTA to give a pink color.[2] As manganese is the only common metal giving a color reaction with EDTA, it has the added effect of masking other metals as colorless complexes. History The test was originally developed by Ludwig Wilhelm Winkler, in later literature referred to as Lajos Winkler, while working at Budapest University on his doctoral dissertation in 1888.[3] The amount of dissolved oxygen is a measure of the biological activity of the water masses. Phytoplankton and macroalgae present in the water mass-produce oxygen...
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...Lab Report on Osmosis and Diffusion Biology 1, Period 3 March 15, 2010 Lab Team: Jason Perez, Kicia Long, Chris McLemore Purpose: The purpose of this lab is to observe the acts of passive transport: diffusion and osmosis in a model membrane system. The experiment will show how molecules in solution move from areas of higher concentration to areas of lower concentration. The model membrane is dialysis tubing. Materials Used 2.5 cm dialysis tubing 15% glucose solution glucose test strip 1% starch solution distilled water Lugol’s iodine solution Procedure: Each member of the lab group will complete the procedures independently 1. Obtain a 30 cm piece of 2.5-cm dialysis tubing that has been soaking in water. Tie off one end of the tubing to form a bag. To open the other end of the bag, rub the end between your fingers until the edges separate. 2. Place 15 mL of the 15% glucose/1% starch solution in the bag. Tie off the other end of the bag, leaving sufficient space for the expansion of the contents in the bag. Record the color of the solution and weight of the bag in a data table. 3. Test the 15% glucose/1% starch solution for the presence of glucose using a test strip. Record the results in the data table. 4. Fill a 250 mL beaker or cup two-thirds full with distilled water. Add approximately 4 mL of Lugol's solution to the distilled water and record the color of the solution in data table. Test this solution...
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...not already done so. (h) After five minutes, remove tube 2 from the water bath and cool it under the tap. Neutralize the acid by adding solid sodium bicarbonate, a little at a time, until the addition of one portion produces no fizzing. Place tube in the rack and return to tube 3. (i) After ten minutes in the water bath, remove tube 3, cool and neutralize the contents as described in (h). Place the tube in the rack. (j) After fifteen minutes in the water bath, remove tube 4; cool and neutralize as before, and place it in the rack. (k) With a dropping pipette, remove a sample of the liquid from tube 2 and place 3 drops on a spotting tile. Rinse the pipette and repeat the procedure for tubes 3 and 4. Add one drop of dilute iodine to each drop of liquid on the tile. (l) Rinse the syringe or pipette and use it to place 3 cm3 Benedict's solution in each of tubes 2, 3 and 4. Return all three tubes to the water bath...
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...12.097 Environmental Chemistry of Boston Harbor – IAP 2006 Lab 1: DETERMINATION OF DISSOLVED OXYGEN BY WINKLER TITRATION 1. Background Knowledge of the dissolved oxygen (O2) concentration in seawater is often necessary in environmental and marine science. It may be used by physical oceanographers to study water masses in the ocean. It provides the marine biologist with a means of measuring primary production - particularly in laboratory cultures. For the marine chemist, it provides a measure of the redox potential of the water column. The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by Winkler in 1888 (Ber. Deutsch Chem. Gos., 21, 2843). Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes; such electrodes require frequent standardization with waters containing known concentrations of oxygen. They are particularly useful in polluted waters where oxygen concentrations may be quite high. In addition, their sensitivity can be exploited in environments with rapidly-changing oxygen concentrations. However, electrodes are less reliable when oxygen concentrations are very low. For these reasons, the Winkler titration is often employed for accurate determination of oxygen concentrations in aqueous samples. 2. Scope and field of application This procedure describes a method for the determination of dissolved oxygen in aqueous samples, expressed as mL O2 (L water)...
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...Major health problems in india : Major health problems in india communicable disease problem population problem environmental sanitation problem medical care problem nutritional problem COMMUNITY NUTRITION PROGRAMMES: INTEGRATED CHILD DEVELOPMENT SERVICE (ICDS) SCHEME : Integrated Child Development Service (ICDS) scheme was launched on 2nd October, 1975 (5th Five year Plan) in pursuance of the National Policy For Children started in 33 experimental blocks Success of the scheme led to its expansion to 2996 projects by the end of March 1994. Now the goal (Ninth Five Year Plan ) is universalization of ICDS throughout the country. Beneficiaries : Beneficiaries 1. Children below 6 years 2. Pregnant and lactating women 3. Women in the age group of 15-44 years 4. Adolescent girls in selected blocks Objectives : 1. Improve the nutrition and health status of children in the age group of 0-6 years 2. Lay the foundation for proper psychological, physical and social development of the child 3. Effective coordination and implementation of policy among the various departments 4. Enhance the capability of the mother to look after the normal health and nutrition needs through proper nutrition and health education. The Package of services provided by ICDS : 1. Supplementary nutrition, Vitamin-A, Iron and Folic Acid 2. Immunization 3. Health check-ups 4. Referral services 5. Treatment of minor illnesses 6. Nutrition and health education to women 7. Pre-school...
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...Investigating the Permeability of Dialysis Tubing Using Potassium Iodine in an Aqueous Starch Solution. Biology 1492 Section 202 Introduction: In order to determine whether potassium iodine or starch will move across a semipermeable artificial membrane. We used a piece of dialysis tubing to serve as the artificial semipermeable membrane, the tubing allows some molecules or ions to pass through, but not others, the rate at which it will pass through depended on the temperature of the solutions used. The expected results were that when the potassium iodine combined with the starch it would turn the solution a dark purple/black color. In previous tests the color of the solution containing starch along with potassium iodine were determined to be true. The results we possible because of osmosis when the water combined with the potassium iodine had the ability to pass through the semipermeable membrane causing the two solutions to combine. Materials Used: * 1 piece of dialysis tubing (wet) * 2 Clamps * 1 250 mL beaker * 1% soluble starch solution * 20 drops of potassium iodine reagent * 1 Disposable pipette Methods: First we obtained all the materials needed and set up the experiment. We then filled a 250mL glass beaker with a 125mL of deionized water. Clamped one end of an approximately 6 inch dialysis tube, using the disposable pipette we opened the dialysis tube, then placed 59.8 degree Celsius 1% soluble starch solution inside tubing still using...
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...prediction is yes it will be able to diffuse. The next question is will iodine be able to diffuse. Again the prediction is yes it will be able to diffuse. The next question asked was will starch be able to diffuse. The prediction was actually no the starch will not diffuses through a membrane. Finally the last question asked was will the weight of the bag change. The prediction was yes the weight will increase. Procedure: The first thing you need to do for this experiment is get a 15cm cellophane dialysis tube and soak it in water until it is soft. Then you need to rub the cellophane between some fingers until it is possible to get an opening on either side. After that put a glass rod between the opening in the tube. Next, take the glass rod out and tie one of the ends with a piece of thread as tight as you can. The next step is to fill the tube about half way with the starch solution and 10ml of a glucose solution. After these steps are completed, tie the other end off with another piece of thread. Then take the tube and weight it on a scale. Once completed, record the weight of the tube. Next fill a beaker to 150ml with tap water and add 6 drops of iodine to it. Place the tube in the water/iodine and make sure the whole tube is in the water. Keep the tube in the water for 30 minutes. While waiting, see if predictions can be made. Finally take out your bag. Take 5 pipets full of the solution with the iodine and put it in a test tube. Then add one pipet of benedicts. Place that...
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...not already done so. (h) After five minutes, remove tube 2 from the water bath and cool it under the tap. Neutralize the acid by adding solid sodium bicarbonate, a little at a time, until the addition of one portion produces no fizzing. Place tube in the rack and return to tube 3. (i) After ten minutes in the water bath, remove tube 3, cool and neutralize the contents as described in (h). Place the tube in the rack. (j) After fifteen minutes in the water bath, remove tube 4; cool and neutralize as before, and place it in the rack. (k) With a dropping pipette, remove a sample of the liquid from tube 2 and place 3 drops on a spotting tile. Rinse the pipette and repeat the procedure for tubes 3 and 4. Add one drop of dilute iodine to each drop of liquid on the tile. (l) Rinse the syringe or pipette and use it to place 3 cm3 Benedict's solution in each of tubes 2, 3 and 4. Return all three tubes to the water bath...
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