enthalpy

# enthalpy - Emily Bissel November 8 2007 Lab Partner Becca...

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-3666.8 J . .01020 mols Mg -2760.4 J . .01020 mols Mg -1153.6 J . .01092 mols MgO -1071.2 J . .01087 mols MgO -359 kJ/mol Mg + -271 kJ/mol Mg 2 -106 kJ/mol MgO + -98.5 kJ/mol MgO 2 Actual - Theoretical Theoretical -498.7 - (-601.6) (-601.6) Emily Bissel November 8, 2007 Lab Partner: Becca Angell Thursday AM Calculating the Enthalpy of MgO by Use of a Calorimeter When physical or chemical changes occur to matter, the result is a change of transfer of energy, which is generally measured in heat. Calorimeters, or a container which traps all of the heat within the experiment into a controlled area, are used in laboratory experiments in order to determine the amount of heat transferred in or out of a substance during a chemical reaction. In this experiment, a coffee cup calorimeter, a Styrofoam cup with two holes in the lid; one for a temperature probe and another for a stirrer), was used. By use of the calorimeter, the change in heat measurement or enthalpy ( H) can be taken at a constant pressure and temperature. If the change in heat is positive (the final temperature of the system is smaller than the initial temperature), the reaction is endothermic. If the change in heat is negative (the final temperature of the system is greater than the initial temperature), the reaction is exothermic. The enthalpy of a reaction performed in a calorimeter can be calculated by use of three values: the heat capacity, the mass of the substance used in the reaction, and the change in temperature;

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enthalpy - Emily Bissel November 8 2007 Lab Partner Becca...

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