Mitchell Graded Exp 7

Mitchell Graded Exp 7 - Experiment 7 Thermochemistry Spring...

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Experiment 7 – Thermochemistry Spring 2008 Name Lab Day and Time TA Section Documentation Possible Points Points Received Introduction 10 Purpose of report Goals of the experiment Materials and Methods 10 Reference lab manual Only describe deviations Results and Discussion 60 Inserted titles for tables Inserted graphs into template Inserted captions for each graph Showed complete sample calculations Summarized all data in tables Answered questions completely Error analysis Laboratory Technique 20 TOTAL (100) TA Comments/Suggestions:
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C HEMISTRY 11L R EPORT T EMPLATE EXPT. Thermochemistry 7 Introduction The purpose of this report is to illustrate the additivity of heats of reaction (Hess’s Law) and to define and investigate exothermic and endothermic reactions. The objective of the experiment was to introduce the concept of thermochemistry. Significance. Your showing the additivity of multi step reactions, this is very important for determining heats of reactions for reactions that cannot be determined experimentally. -5 Materials and Methods The procedure for this experiment was taken from the University of North Carolina at Chapel Hill Chemistry 101 Lab Manual. There were no deviations from the given procedure. After the hardware, interface, and software were set up, two styrofoam cups and a lid were obtained. One styrofoam cup was placed inside the other. A stir bar was placed in the top cup. The apparatus was placed on a stir plate next to a metal support rod the bench top. After the temperature sensor was suspended in the styrofoam cup without touching the base of the cup, a clamp was used to fix the temperature sensor in place. Using a graduated cylinder, 50.0 mL of distilled water was added to the calorimeter. The temperature sensor was placed into the calorimeter, and the stir plate was adjusted to a slow speed. Two grams of sodium hydroxide was weighed out by difference, and the mass was recorded to the nearest 0.001 g. After the calorimeter was assembled and the sodium hydroxide sample was ready, time- temperature readings were taken for three minutes. After the initial three-minute interval, the solid sodium hydroxide was added to the calorimeter, and the time of mixing was recorded. Time-temperature readings were recorded for a total of ten minutes. The stir bar was removed from the calorimeter, and the contents of the calorimeter were emptied into the sink. The styrofoam cup and stir bar were rinsed with distilled water, and the calorimeter was reassembled for the next reaction. Using a graduated cylinder, 50.0 mL of 1.0 M HCl was added to the calorimeter. The calorimeter was reassembled with the lid and temperature sensor in place, and the stir plate was adjusted to a moderate speed. Fifty milliliters of 1.0 M NaOH was measured into a clean graduated cylinder. Time- temperature readings for the 1.0 M HCl solution were collected for three minutes. The NaOH solution was added to the calorimeter, and the time of mixing was recorded. Time-temperature readings were
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Mitchell Graded Exp 7 - Experiment 7 Thermochemistry Spring...

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