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Bomb Calorimetry - Henry Nguyen Hhn247 52670 Leigh Krueger...

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Henry Nguyen Hhn247 52670 Leigh Krueger Experiment #7 Bomb Calorimetry Introduction The purpose of this experiment is to use a bomb calorimeter to find the standard enthalpy of formation for various compounds. The sample, in this case anthracene, is loaded into the bomb calorimeter and was detonated in a water bucket. The rise in temperature within the bomb calorimeter indicates a combustion reaction occurred. From this change in temperature, the enthalpy of combustion can be measured, which can be used to figure out the enthalpy of formation by applying Hess’ Law. 1 Data and Observations Bomb specific precautions were followed. According to PChemLab Wiki: 2 o Steps 2-3 were skipped because these steps apply to an older version of the Bomb Calorimeter program. o Steps 4-6 were skipped – thermocouple calibration was provided. o About 0.500 – 0.600 ± 0.001 g of sample is needed for each sample pellet. Three runs were conducted for benzoic acid and anthracene each. Table 1 – Average Thermocouple Reading Calibrations: Thermometer Thermocouple Temperature ( ° C) ∆° C Temperature ( ° C) ∆° C 0.5 0.5 0.976 0.036 13.0 0.5 13.400 0.613 24.0 0.5 24.810 0.133 38.0 0.5 38.805 0.056
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Henry Nguyen Hhn247 52670 Leigh Krueger Experiment #7 50.5 0.5 51.515 0.301 60.0 0.5 61.287 0.223 Table 2 – Benzoic Acid Thermogram Data: Run 1 Run 2 Run 3 Firing Time t a (s) 600.0 500.0 400.0 60% Mark of Total Rise t b (s) 1410.0 1325.0 1330.0 Time Beginning Post Period t c (s) 1950.0 1875.0 1950.0 Firing Time Temperature T a (K) 296.51 296.55 296.88 Post Period Temperature T c (K) 297.75 298.06 298.25 Preperiod Temperature Rise r 1 (K/s) - 2.47 x 10 - 5 1.52 x 10 - 4 -5.19 x 10 -5 Postperiod Temperature Rise r 2 (K/s) 7.06 x 10 -5 9.82 x 10 - 5 1.35 x 10 - 4 dT with r 1 and r 2 (K) 1.22 1.33 1.33 dT without r 1 and r 2 (K) 1.24 1.51 1.36 Table 3 – Benzoic Acid Calorimetry Data: Run 1 Run 2 Run 3 Sample Mass (g) 0.548 0.663 0.583
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Henry Nguyen Hhn247 52670 Leigh Krueger Experiment #7 Wire Length (cm) Int: 10 Left: 1 Used: 9 Int: 9.5 Left: 2 Used: 7.5 Int: 9.8 Left: 1.5 Used: 8.3 Water Mass (g) 1988 1967 1968 Q comb (kJ) -14.6 -17.6 -15.5 C cal (kJ/K) 11.8 11.7 11.4 Average C cal (kJ/K) 11.6 Table 4 – Anthracene Thermogram Data: Run 1 Run 2 Run 3 Firing Time t a (s) 880 1200 395 60% Mark of Total Rise t b (s) 2032 2205 1667 Time Beginning Post Period t c (s) 2800 2875 2515 Firing Time Temperature T a (K) 297.02 297.30 296.34 Post Period Temperature T c (K) 298.98 299.49 298.57 Preperiod Temperature Rise r 1 (K/s) 1.2 x 10 -4 -1.73 x 10 -5 7.01 x 10 -5 Postperiod Temperature Rise r 2 (K/s) 2.1 x 10 -5 2.02 x 10 -4 -5.58 x 10 -6
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Henry Nguyen Hhn247 52670 Leigh Krueger Experiment #7 dT with r 1 and r 2 (K) 1.81 2.07 2.14 dT without r 1 and r 2 (K) 1.96 2.18 2.23 Table 5 – Anthracene Calorimetry Data Run 1 Run 2 Run 3 Sample Mass (g) 0.582 0.592 0.637 Wire Length (cm) Int: 10.2 Left: 1.2 Used: 9 Int: 9.8 Left: 0.5 Used: 9.3 Int: 10 Left: 5.2 Used: 4.8
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