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
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produce iodide ion (I-) and dehydroascorbic acid‚ as shown in the following equation: [IMAGE] + I2(aq) -----------> + 2H+(aq) + 2I-(aq) Ascorbic acid (Vit. C) Dehydroascorbic acid However‚ since iodine is only slightly soluble in water‚ ascorgic acid should not be titrated directly by a standard iodine solution‚ since the end point of titration is not o obvious. Instead‚ back titration will be employed. The titration of a reducing agent with iodine to produce iodide ion is
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Arrhenius stuff The reaction of Hydrogen Peroxide and Iodide ions in an acidic medium: 3 I-(aq) + H2O2(aq) + 2 H+(aq) I3-(aq) + 2 H2O(l) Step 1. H2O2(aq) + I-(aq) IO-(aq) + H2O(l) Step 2. IO-(aq) + H+(aq) HOI(aq) Step 3. HOI(aq) + 2 I-(aq) + H+(aq) I3-(aq) + H2O(l) In this reaction the three iodide ions are oxidised to form the triiodide ion. This occurs in three steps. Firstly‚ the peroxide molecule oxidises a single iodide ion‚ to form a hypoiodite ion‚ and a molecule of water
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oxidation of ascorbic acid by iodine solution. Iodine is relatively insoluble‚ but this can be improved by complexing the iodine with iodide to form triiodide as the following formula suggests: I_(2(aq))+〖I^-〗_((aq))↔〖I^-〗_(3(aq)) This triiodide ion can be used to oxidize vitamin C to form dehydroascorbic acid. In this reaction the triiodide ion is reduced to iodide ion‚ and ascorbic acid‚ C6H8O6 is oxidized to dehydroascorbic acid‚ C6H6O6. Aim The aim of this investigation is to discover the exact
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equilibrium‚ it is impossible to tell whether the reaction has started with the reactants or the products. * For example‚ if you react equal amounts of Hydrogen and Iodine to form Hydrogen Iodide (left)‚ you will end up with the same amount of reactants and products if you had decomposed Hydrogen Iodide (right). Shifting the Position of equilibrium * The position of equilibrium can be altered by changing: * The temperature. * The concentration of reacting substances.
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Uses of Radiation in Medicine Nuclear Chemistry and the Field of Medicine: A Union Shan Gupta‚ Yahoo! Contributor Network Jul 2‚ 2009 "Contribute content like this. Start Here." Applications of Radiation in the Field of Medicine Overview: With the discovery of radiation in the late 1800’s by Antoine Henri Becquerel‚ Marie Curie‚ and Pierre Curie‚ the powers of the atom were seemingly multiplied greatly. With this new power of the atom also came new uses for it‚ especially in the
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concentration of ions to produce a current; therefore‚ the sodium sulfate was acting as the salt bridge in the reaction. This processes was demonstrated in parts B and C as well; however‚ instead of the sodium sulfate acting as the salt bridge‚ potassium iodide was substituted in part B and potassium chloride in part C. In each part of the procedure a different indicator was used – part A was accompanied by a universal indicator‚ part B was joined with phenolphthalein‚ and part C was combined with bromothymol
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Formal lab report: Chemical or Physical Change? Problem: The purpose of this lab is to discover which observations indicate that a ………………….chemical change has taken place. Materials: Part 1: Lead [II] nitrate; Potassium iodide; 2 Test tubes; Test tube rack Part 2: The materials are found on page 161 in the textbook Sciencepower 9 Part 3: The materials are found on page 161 in the textbook Sciencepower 9 Part 4: 100 mL Beaker; Hot plate; Beaker tongs; Wire gauze;
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Unit 3 – Virtual Labs Letizia Schianodicola Lab #1 – Atomic Weight of Magnesium 1. Moles of hydrogen evolved‚ from chemical property dialog for beaker: a. 0.000411 mol H2 2. Calculate the atomic weight of Magnesium. Atomic weight of Mg = weight of Magnesium/moles of H2. b. 59‚136.253 g/mol Mg (24.305 - weight of Mg / 0.000411 mol H2) 3. Calculate the # of molecules of H2 that were produced in the reaction – use Avagadro’s number –
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Determination of Chlorine and Iodine in Water I. Introduction The purpose of this laboratory was to determine the amount of chlorine and iodine in a sample of water by titration using a starch indicator and to standardize a sodium thiosulfate solution. Chlorine is added to municipal water supplies to purify it enough to become safe to drink. Iodine is also added to water when people camp or go hiking in the back country where they cannot bring purified water along. Chlorine and iodine are
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