2lab2 - JessicaGaboriault LabReportSectionATuesday2pm...

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Jessica Gaboriault Lab Report – Section A Tuesday 2pm Lab Partner: Jacki Lerea 2/10/08 Experiment 2 : Free Energy in Chemical Reactions Introduction :  In this experiment, we will determine the heats of  H° of neutralization for 2 Δ   weak acids and determine the corresponding equilibrium constants Ka for the dissociation of  these weak acids.  These measurements will provide us with the values of  G°. Δ For the procedure, see pages 5-14 in the lab manual. *** We used two thermometers instead of  one throughout the experiment and especially in part one: determining the calorimeter constant. Data and observations : Thermometer 106 – 19.9°C in tap water Thermometer 215 – 20.4°C in tap water *** To account for this difference in temperature, in all of our thermometer readings throughout  the experiment, we added 0.5°C to each reading of the 106 thermometer. Determination of the Calorimeter Constant  For this part, the data here was taking the temperature of the hot and cold water separately,  then pouring the cold water into the hot water which was in the Dewer flask and recording the  temperature  over a 4  minute  period. Time Temperature for  cold water Temperature for  hot water Initial 18.6°C 44.3°C 30 seconds 18.7°C 44.1°C 1 minute 18.7°C 43.9°C 1 minute 30 seconds 18.7°C 43.7°C 2 minutes 18.7°C 43.5°C 2 minutes 30 seconds 18.6°C 43.4°C 3 minutes 18.7°C 43.2°C 3 minutes 30 seconds 18.7°C 43.1°C 4 minutes 18.7°C 43.0°C
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Time Temperature for mixture of hot/ cold water Initial 31.9°C 30 seconds 31.5°C 1 minute 31.6 °C 1 minute 30 seconds 31.6°C 2 minutes 31.6°C 2 minutes 30 seconds 31.6°C 3 minutes 31.6°C 3 minutes 30 seconds 31.6°C 4 minutes 31.6°C
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For part 2: Determination of the Enthalpy Change,  H° Δ - We were working with sodium hydroxide, acetic acid, and chloroacetic acid.  For the base  (NaOH), we used the 1.02 M solution and for the acids (acetic and chloroacetic) we used  the 1.00 M solution. - Measurement of the temperature of the  NaOH  in the insulated flask  21.3°C - Measurement of the temperature of  acetic acid  solution in graduated cylinder 21.4°C
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- - *** First time – NaOH and acetic acid mixture Time in  seconds Temperature in  °C 0 28.3 30 28.4 60 28.3 70 28.2 150 28.4 170 28.4 190 28.4 210 28.4 230 28.4 250 28.4
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***Repeat of the NaOH/acetic acid Acetic acid temperature initial – 21.0°C Base temperature initial – 20.8°C Time in seconds Temperature in °C 10 27.3 30 27.4 50 27.5 70 27.6 90 27.5 110 27.6 130 27.5 150 27.5 170 27.5 190 27.5 210 27.5 230 27.5 250 27.5
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The next part of part 2 involved the same experiment but with choloroacetic acid and NaOH. Choloracetic acid initial temperature – 20.9°C
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2lab2 - JessicaGaboriault LabReportSectionATuesday2pm...

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