Lab 22 Procedure Part 1

Lab 22 Procedure Part 1 - Experiment 22 Dystan Medical...

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Experiment 22 Dystan Medical Supply Company: A Self-Directed Experiment March 20, 2009 1
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Introduction The use of hot and cold packs are widely used around the world are serve as a great relief for short-term pain. Many people are aware of its extensive uses for athletes or even for warming up on a chilly day. These packs are made from a bag that is comprised of two separate sections, the first one is made up of a salt and the other one contains water. When someone breaks the bag, the salt (solute) will dissolve in the water (solvent), thus creating either an endothermic or exothermic reaction which ultimately depends on the concentration of salt. Both of these types of reactions can create either a hot or a cold pack, depending on whether heat is absorbed or released. An endothermic reaction is known to generate a cold pack because the heat and energy are absorbed from the environment while an exothermic reaction is known to produce a hot pack as a result of heat and energy being released to the atmosphere. This experiment is comprised of testing four different salts in order to see which ones will work the best for producing these hot and cold packs. These salts are ammonium nitrate, calcium chloride, lithium chloride, and potassium chloride. Not only will we determine which one is the most resourceful for creating these packs, but we will also consider how much it will cost to actually produce them for the Dystan Medical Supply Company. In order to do this, we must find a way to determine the mass of each individual necessary in the production of a 100-mL cold pack that can attain a temperature of 0°C and a 100-mL hot pack that can reach a temperature of 65°C. To carry out our experiment, we will construct a calorimeter and record numerous thermograms using the MeasureNet station. In return, we will be able to tell from our calculations if the salt reactions are either endothermic or exothermic, thus revealing which salt is essential for the production of each type of pack. This experiment deals heavily with calorimetry, the amount of heat necessary or produced in a chemical reaction. We must first create our own calorimeter with two styrofoam cups and determine the calorimeter constant—the amount of heat that the calorimeter absorbs from its surroundings. Once this is completed, we can go on to actually testing each salt. Water is added to the constructed calorimeter and the initial temperature is recorded. The salt is then added to the calorimeter, and the changes in temperature are recorded as a thermogram from MeasureNet. One can expect to either see an increase in 2
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heat or decrease in heat from the graphs and from this, will be able to determine the overall change in temperature. Further calculations involving specific heat, the calorimeter constant and temperature changes are done and reveal how much total energy a reaction creates or absorbs. This in turn allows us to see if the reaction is exothermic or endothermic based on the sign of the energy values. A positive sign
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Lab 22 Procedure Part 1 - Experiment 22 Dystan Medical...

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