...Experiment 8: Redox: Analysis of the Oxidizing Capacity of Bleach PURPOSE In this experiment, you will show how redox reactions can be used to quantitatively determine the amount of oxidizing agent in liquid hypochlorite household bleach. There are two oxidation-reduction reactions for determining the oxidizing capacity of bleach. Initially an excess of iodide ions are added to a bleach solution. The iodide ions are oxidized to iodine after the solution has been acidified. Starch is added to the resulting iodine solution as an indicator. The solution is then titrated with sodium thiosulfate until the color of the solution changes indicating the endpoint of the reaction. Data collected from the titrations will be used to calculate the mass of the sodium hypochlorite in an unknown solution of bleach. Given the original mass of the unknown solution and the calculated mass of the sodium hypochlorite in the unknown solution, the percent by mass of the sodium hypochlorite can be determined. The oxidizing capacity of the unknown bleach is effectively the percent by mass of the sodium hypochlorite in the unknown bleach sample. OJECTIVES 1) Titration of a sample of bleach with thiosulfate. 2) Determining the end point of the titration with starch indicator. 3) To determine oxidizing capacity of bleach by determining the percentage by mass of the bleach that is sodium hypochlorite. 4) Balance and summarize the two redox reactions to determine the overall chemical reaction that...
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...The objectives of “Lab 8: Lemon Car Competition” were to use redox reactions to store energy in capacitors, to learn about battery cells and construct a lemon citrus cell to power devices, and to build a vehicle powered by either a lemon battery or a capacitor to be entered in a competition. The competition objective was to win the competition. The winner was the vehicle with the highest competition ratio, which was calculated using Equation 1 below. To have the highest competition ratio, the cost and time traveled were minimized and the distance traveled was maximized. The designed vehicle came in last place along with three other vehicles because it did not travel. The car costed $3.50 and traveled 0 foot, so the competition ratio was zero....
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...Copper Cycle The copper cycle involves many different type of reactions. In this lab you will investigate the various types of reactions that are used to complete the cycle. Solid copper will be added at the beginning of the reactions. Due to the law of conservation of matter the amount of copper put into the reaction should also come out of the reaction at the end. The reactions that you will perform are generally outlined in the following cycle: Reactions: 1. 8HNO3 (aq) + 3Cu (s) + O2 (g) 3Cu(NO3)2 (aq) + 4H2O (l) + 2NO2 (g) 2. Cu(NO3)2 (aq) + 2NaOH (aq) 3. Cu(OH)2 4. CuO (s) + H2SO4 (aq) 5. CuSO4 (aq) + Zn (s) Materials: 250 mL beaker Aspirator H2O Glass funnel Rubber tubing 15 mL - 6.0 M Sulfuric Acid Ring stand Bunsen burner 2.0 g Zinc powder Ring 0.5 g copper wire 10 mL - 6 M Hydrochloric Acid Wire Gauze 4.0 mL - 16 M Nitric Acid Finger clamp 30 mL - 3.0 M NaOH Set-Up: 1. Create a fume hood from a funnel surgical tubing and aspirator. 2. Support the 250 mL beaker with a ring and wire gauze. 3. Connect the funnel with a finger clamp over the 250 mL beaker. 4. Connect hose to funnel and aspirator (fume hood maybe used in lieu of funnel and aspirator set-up). Procedures: 1. Mass a 250 ml beaker and record in the data table. 2. Mass out approximately 0.500 grams of no. 16 copper wire and record the mass of the copper in the data table and place...
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...CU/Balance zinc (copper plated zinc). The nickel is 25% nickel/balance CU (cupronickel). The dime is 8.33% balance CU (cupronickel). The quarter is 8.33% Balance CU (cupronickel). Tarnish on coins happen when the metal combines with oxygen. Oxidation, which causes tarnish, is a chemical reaction. Oxidation also happens with reduction, which is when something gains electrons. pH (on the pH scale) stands for “the power of “H”, or hydrogen. The lower something is on the pH scale, the higher its acidity. Rust can weaken a coin or any other metal material. The green patches on coins are called copper oxide. It is caused by oxidation. When an acid reacts with tarnish, it makes the coins shiny. In order for oxidation to occur, the air has to be damp. In my experiment I used specific solutions to clean coins. Lemon juice has a ph of 2.2. Baking Soda has a pH of 8.4. Water has a Ph of 7. Orange juice has a Ph of 3.70. Cola has a Ph of 3.18. Dishwashing liquid has a pH of 7.80. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are alkaline or basic. Pure water is neutral and isn’t an acid or a base. pH is an important measurement used in various medical, biological, chemical, environmental, and nutritional labs. pH standards are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard...
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...Experiment 2: The Chemistry of Copper I. Introduction Copper is one of the most important metals because it is one of the best conductors of heat and electricity and an alloying element in bronze and brass. Copper is a soft metal with a bright orange-brown color in which is often called “copper color”. Also, copper is an element that is chemically combined with several of compounds in nature. Usually, these compounds are blue or blue-green depending on the copper(II) species. In this lab we are to observe many of the physical and chemical properties of copper by cycling copper via several chemical reactions; those reactions being, Oxidation Reduction, Acid-Base and Oxidation-Reduction and Single Displacement Reduction. Lastly, while performing a series of chemical processes, the mass of copper recovered should equal the original mass of copper from the beginning. II. Data (Experimental Observations) Part A: Oxidation Reduction Reaction The weight of the copper starting material was 0.107g. After I weighted the copper, I wrapped the turning into a small ball and place it into a 150 mL beaker. Then, I measured 8 mL of 6 M nitric acid, HNO3, into a 10 ml graduated cylinder. Afterwards, I then slowly added the 6 M HNO3 into the beaker containing the copper. Then, I cover the beaker with a watch glass and observe the reaction. As I was observing the reaction, I noticed that the color of the copper solution went from a clear to a baby blue color. As the copper slowly...
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...Introduction: This lab is destined to calculate the cell potential of different electrochemical cell. Electrochemical cells is very useful in everyday life. Thanks to them, we have batteries that powers our mobile phones, laptops and so on.. Electrochemical Cells are devices in which chemical energy released during a chemical reaction is converted into electrical energy . A typical cell might consist of two half cells. Each half-cell consists of cathode, electrode where reduction(gain of electrons) is happened, or anode in which oxidation(loss of electrons) is happened, and electrolyte, a solution containing the corresponding cation(metal) of the half-reaction. The electrode of the half-cells are connected by a wire along which the electrons flow. And two solutions are separated by a salt bridge. As long as electrode is dipped in its electrolyte, potential difference is developed at the metal solution interface. The potential difference between the two electrodes in a galvanic cell is called a cell potential or emf of the cell. Thus magnitude of the potential depends on the nature of metals...
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...was also to balance and classify the different reactions involved in the cycle and to identify and write the formula unit, total ionic and net ionic equations for the precipitation and acid-base reactions in this experiment. The first reaction that occurred was when a piece of copper was added to a solution of HNO3. This resulted in a green solution that let off brown fumes. These brown fumes were from the oxidation of the copper and left a clear blue solution. The next reaction occurred when 30.0 mL of 3.0M NaOH was added. This caused the clear blue solution to turn into a bright blue, gelatinous solution. This was caused by the addition of the base, which resulted in the precipitation of the copper hydroxide. Heat was added to the solution, which caused the hydrogen to leave, and the solution to form a black precipitate. Fourthly, the addition of H2SO4 caused the solution the solution to turn into a clear light blue solution, copper sulfate. Lastly, when the Al was added to the solution the solution turned red and fizzed and turned clear. This was caused by the reduction of the copper cations by the Al to yield metallic copper. The unreacted Al was removed by the addition of the hydrochloric acid. These reactions are endothermic because they needed to be heated up to occur. The first reaction was done in the hood because when the copper and the HNO3 were combined it resulted in brown fumes being let off. This is an...
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...rancidity are derived from human thresholds for detecting off-flavors associated with rancidity. Therefore, it is assumed that feeding fats that have undergone severe oxidation may reduce feed consumption and growth rate in animals. Oxidative rancidity is a complex process that is thought to occur in phases: (1) initiation, (2) auto-oxidation and (3) termination. During each phase, the formation of products increase and decrease over time, as shown in Figure 1. Hydroperoxides form when oxygen and unsaturated fatty acids combine in the presence of a catalyst (such as iron, copper, heat, light, enzymes, etc.) during the initiation phase. These peroxides are reactive and can combine with other fats to form additional reactive products during auto-oxidation. Hydrocarbons, aldehydes and ketones are formed during the termination or final phase. These compounds are volatile, but relatively unreactive. The best in vitro indicator of rancidity for feeds and feed ingredients has not yet been defined. Rancidity is a qualitative term or state that is not chemically defined and is not quantifiable. As a result, a number of different methods have been used to test for various intermediates or products of oxidation. However, these products are “moving targets”, so it is not possible to predict the best indicator of fat oxidation. N-PAL (2001) described various methods used to predict or interpret the rancidity of fats....
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...production of ethanol in a versatile lab fermentor Abstract Whether used for research or production, the versatile BioFlo® 310 fermentor from New Brunswick Scientific allows growth of a wide variety of aerobic and anaerobic microorganisms, including bacteria, plant, algae, fungi and yeast. Its advanced controller can regulate up to four vessels simultaneously, 120 process loops in all. Here we demonstrate one facet of its versatility—a technique for inducing ethanol production in yeast, by switching from an aerobic growth phase to an anaerobic steady-state culture. Introduction Saccharomyces cerevisiae is a model eukaryotic organism, often used in research because it is easy to manipulate and culture, and is comparatively similar in structure to human cells. This yeast is also widely used in industrial applications to manufacture enzymes and proteins for beer, wine and bread, and because it metabolizes glucose to ethanol, is also used to produce many biofuel products. We produced ethanol from a S. cerevisiae (American Type Culture Collection strain 20602) in a 7.5 liter BioFlo 310 fermentor, to demonstrate the flexibility of this advanced fermentation system. In the first phase, we grew the yeast in an aerobic environment, using a dissolved oxygen cascade control strategy to produce a sufficient cell density. Then we pumped in nitrogen gas to create an anaerobic environment for inducing ethanol production, and used reduction and oxidation (redox) potential measurements to...
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...Experiment 8 Lab Report Analysis of Oxidizing Capacity of Bleach The goal of this lab is to perform a titration of a sample of bleach with thiosulfate, figuring the end point with a starch indicator. We will determine the percent mass of sodium hypochlorite in bleach by using the volume of sodium thiosulfate needed to reach the end point. This value represents the oxidizing capacity of the unknown bleach. At the end, we will create two redox reactions to determine the overall chemical reaction that occurs during this process. I think that my oxidizing capacity will be 5.0g. Most bleach contains salts with the hypochlorite ion, the oxidizing agent that removes stains and whitens them. The hypochlorite ion usually comes in the form of sodium hypochlorite, NaOCl, or calcium hypochlorite. The two oxidation reduction reactions that occur during this experiment are first the oxidation of iodide to iodine, I2(aq), by the hypochlorite ion and then making the aqueous iodine reduce back to iodide by titrating it with sodium thiosulfate. The overall stoichiometry of the reaction is one mole of hypochlorous acid, formed by placing the sodium hypochlorite into acidic solution, plus two moles of the thiosulfate ion plus hydrogen ions from the solution yielding one mole of chlorite anions, one mole of the tetrasulfur hexoxide anion and one mole of liquid water. We began the titration of aqueous iodine by adding .05M sodium thiosulfate until the brown colored solution began to turn a...
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...727) (A-2) Experiment 2 Use of the Pipet and Buret and Statistical Analysis (page 729) Gravimetric Analysis (A-3) Experiment 3 Gravimetric Determination of Chloride (page 730) Volumetric Analysis Acid-Base Titrations Neutralization Titrations (A-4) Experiment 6 Determination of Replaceable Hydrogen in Acid by Titration with Sodium Hydroxide (page 736) (A-5) Experiment 7 Determination of Total Alkalinity of Soda Ash (page 738) Complexometric Titrations (A-6) Experiment 9 Determination of Water Hardness with EDTA (page 742) Precipitation Titrations (A-7) Experiment 11 Determination of Chloride in a Soluble Chloride: Fajan’s Method (page 745) Statistical Comparison of the results obtained from Exp 3 and Exp 11 Reduction-Oxidation Titrations...
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...almost never observed because it is ordinarily further oxidized by the oxygen: 2 Fe(OH)2 + ½ O2 + H2O → 2 Fe(OH)3 The final product (when dry) has the reddish-brown flaky character we associate with rust. Although the reaction that produces Fe(OH)2 is technically an equilibrium process (all electrochemical processes are) the value of Kc is very large (>1099 at 298 K) and left unchecked it will go to completion. But the rate is relatively slow under normal atmospheric conditions and so it is still possible to manipulate the equilibrium somewhat by changing appropriate factors. The rates of corrosion reactions--and presumably their mechanisms--vary widely. Factors which influence the progress of the net reaction in the first step of the oxidation of iron may have an effect on the overall rate. The nature of the oxide product is also very important in affecting the extent of the corrosion. For example, aluminum is a very active metal, but its oxide, Al2O3, is very dense and forms a thin protective layer on the metal which discourages further corrosion. In contrast, iron rust (hydrated forms of Fe2O3 such as reddish-brown Fe(OH)3) is typically flaky and easily crumbles off to continually expose fresh metal for reaction. Although the mechanism for corrosion is not always well understood, it is clear how to prevent it. The surface of the metal must be protected from contact with oxygen. Paints, oils and other coatings are often used for this purpose. But it is...
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...CH 4510: CRE Lab Cyclic Voltammetry \ Aim: To become familiar with using an electrochemical potentiostat To determine the concentration of potassium ferricyanide, K3Fe(CN)6 in an unknown solution using cyclic voltammetry and analyzing the current vs potential graphs Apparatus Required: Potentiostat and electrodes Nitrogen gas for mixing Test tubes Standard flask Reagents required: KNO3 solution 10mM K3Fe(CN)6 solution Theory: Cyclic Voltammetry: Cyclic Voltammetry (CV) is an electrochemical technique which measures the current that develops in an electrochemical cell under conditions where voltage is in excess of that predicted by the Nernst equation. Cyclic voltammetry (CV) is perhaps the most versatile electro-analytical technique for the study of electroactive species. Its versatility dined with ease of measurement has resulted in extensive use of CV in the fields of electrochemistry, inorganic chemistry, organic chemistry and biochemistry. Cyclic voltammetry is often the first experiment performed in an electrochemical study of a compound, biological material, or an electrode surface. The effectiveness of CV results from its capability for rapidly observing the redox behavior over a wide potential range. The resulting voltammogram is analogous to a conventional spectrum in that it conveys information as a function of an energy scan. Instrumentation: The main components of a Cyclic Voltammeter are the Reference electrode...
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...3. Termites A. Spirochetes play a fundamental role when it comes to the nutrition of termites. They use acetate produced by microbes as a major source of energy and of Carbon. Spirochetes N2 fixation also plays an important role in the nitrogen economy of termites. The N2 fixation of these spirochetes is significant for a lot of different environments B. Acetogenic spirochete: -Spirochetes that have been previously cultured, posses the ability to conserve their energy by the oxidation of H2 -The reduction assay of acetylene assays for the cells’ nitrogenase activity Termite: -Oxidation of the Acetate produced by the hindgut microbes is one of the most important sources of energy and Carbon for termites. It supports 100% of the insects’ respiration requirements...
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...measurement of a solution of known concentration when it reacts completely with a measured volume or mass of another substance. In the first part of this experiment, the potassium permanganate solution, the titrant, is standardized, by quantitatively reacting it with iron (II) ammonium sulfate hexahydrate, Fe(NH4)2(SO4)2•6H2O (abbreviated FAS). The second part of the lab uses the standardized potassium permanganate to determine the amount of the analyte, also iron (II), in iron supplement pills. In this experiment, a purple-colored solution of potassium permanganate, KMnO4, with an approximate concentration of 0.02 M will be added to solutions containing Fe2+ ions. In redox titration the chemical reaction is an oxidation-reduction reaction with electrons transferred from one species to another. The total number of electrons lost in the oxidation half-reaction is equal to the total number of electrons gained in the reduction half-reaction. The permanganate ion, MnO4-, is a strong oxidizing agent which causes the Fe2+ to be oxidized to Fe3+ ions. The manganese gains five electrons and is reduced from a 7+ oxidation state in the permanganate ion to form colorless Mn2+ ions. The Fe2+ loses one electron as it is oxidized to Fe3+. The end point is indicated when the reaction is complete at the point when all of the Fe2+ ions in solution are oxidized and the colorless mixture retains the purple tint of unreacted permanganate. Note that the color may be somewhat orange in appearance...
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