Lab Report 6 - Purpose: The purpose of this experiment is...

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Purpose : The purpose of this experiment is to use calorimetry to calculate the enthalpy change of the combustion reaction: 2Mg(s) + O 2 (g) 2MgO(s). Calorimetry is the process of measuring the flow of energy between the chemical reactions and their surroundings. This enthalpy change can be calculated using Hess’s Law by adding the H values of three separate reactions. Methods : The experiment began with measuring the temperature change for a reaction with a known enthalpy to discover the heat capacity of the calorimeter itself, an insulated structure that keeps heat contained. The calorimeter is weighed without its lid, then filled about half way with water that is at room temperature and re-weighed. The water’s temperature was measured and recorded every 30 seconds by placing a thermometer though the lid of the calorimeter. Another thermometer was used to measure the temperature of an ice bath, consisting of water and a large amount of ice in a large beaker. Once both temperatures stabilized, the cold water of the ice bath was added to the calorimeter to make it about ¾ full. The temperature was measured and recorded every 30 seconds until stable, and it is re-weighed without its lid. The second investigation involved the reaction of magnesium and hydrochloric acid. 100 mL of 1.00 M HCl was made by mixing 20 mL of the concentrated acid with 80 mL of diluted water. This solution was poured into the calorimeter, and the mass was recorded as well as the temperature every 30 seconds. About 0.25 g Mg was measured and added quickly to the calorimeter. The temperature was recorded every 30 seconds
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until stable. The third and final investigation involved the reaction of magnesium oxide and hydrochloric acid. The same solution of 100 mL of 1.00 M HCl was prepared and added to the calorimeter, its temperature measured and recorded in the same way as previous investigations. About 1 gram of MgO was measured and added carefully since it is a powdery substance and can be blown around easily. The calorimeter was
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This note was uploaded on 03/17/2009 for the course CHEM 1A taught by Professor Nitsche during the Fall '08 term at University of California, Berkeley.

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Lab Report 6 - Purpose: The purpose of this experiment is...

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