3/22/14 Mr. Mihordea Motion of Atoms and Molecules lab summary
In this lab the standard heat of combustion of magnesium was calculated by using the calorimeter. Also, the point of combustion of magnesium was to see how much heat would be released from fireworks such as sparklers. The concept of this lab was to find the difference in temperature from the beginning to end of combustion of magnesium and calculate the standard heat of combustion of magnesium by using the calorimeter and a thermometer. By using the thermometer, we found out the change in temperature which helped to find the specific heat of water. The reactions were exothermic because of heat that was released into the surroundings from the reaction. Exothermic is a reaction of process that releases energy in the form of heat. Also, the Q that was measured is –Q of the reaction because Q system = -Q Water. After the difference in temperature from beginning to end of the reaction was taken, the Q = m∙c∙ΔT was used to find the Q of Water and system. Then 1 mole was converted into kilojoule per mole. The kilojoule per mole calculated was used in Hess’s law in order to calculate delta H. As there are always some errors in a lab, the amount of hydrochloric acid could have been off by ±1 or 2mL. When the thermometer was put into the calorimeter, it made a hole which helped the heat to escape from the calorimeter. Also the initial temperature of the water could have been different for every reaction. The percent error in our lab was -4.89%.
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