University of Washington CHEM 152 Experiment 4: Thermodynamics I (Calorimetry) (GRADED A)

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DATA AND CALCULATIONS A: Heat Capacity of the Calorimeter Run 1 Run 2 Run 3 Voltage, V (J/C) 2.2 2.2 2.2 Current, A (C/s) 2.24 2.28 2.25 Time (s) 420 410 420 Initial temperature, oC 25.7 26.4 26... .7 Final temperature, oC 30.4 31.0 31.3 *Energy into calorimeter from power supply, (q), J 2070 2060 2080 *Heat Capacity of Calorimeter, Ccal, J/oC 440 447 452 Average, Ccal 446 J/oC Standard Dev 5.81 J/oC B: Enthalpy of Fusion of Water Run 1 Run 2 Ccal(Average), J/oC 446 446 Mass of calorimeter, stir bar and water, g 113 113 Mass of calorimeter, stir bar, and water + mass of added ice (or melted ice), g 115 115 Mass of ice, g 2.52 2.68 Temperature of calorimeter before ice addition, oC 26.4 26.3 Temperature of ice before addition to the calorimeter, oC 0.0 0.0 Temp. of the calorimeter after addition and melting of the ice, oC 23.4 23.0 Tcal -3.00 -3.30 * (a) Heat lost by calorimeter (q cal in J) -1,340 -1,470 water from ice 23.4 23.0 Specific heat of water, J/g.oC 4.18 4.18 * (b) Heat gained by ice cube to warm water from ice temperature (q in J) 247 258 *(c) Enthalpy of fusion of ice, H fusion in J/g 434 453 Average H 443 J/g Standard Dev 13.4 J/g Chem 152 Experiment #4: Thermodynamics I (Calorimetry) *Type an example of the calculations you are performing for q and Ccal. (3 pts) q = current * voltage * time = 2.24 C/s * 2.2 J/C * 420 s = 2069.76 J ≈ 2070 J Ccal = q / T = 2069.76 J / (30.4oC - 25.7oC) = 440.374 J/oC ≈ 440 J/oC *Type examples of the calculations you perform for the following: (a) q cal (2 pts) (b) q for heating the water that was ice (warming melted ice) (2 pts) (c) Hfusion (melting the ice) (2 pts) -qcal = -CcalT = -446.469 J/oC * -3 oC = 1339.407 J ≈ 1340 J qcal = -1340 J qwater that was ice = 4.184 J/goC * 2.52 g * 23.4oC = 246.722 J ≈ 247 J Hfusion = (1339.407 J - 246.722 J) / 2.52 g = 433.605 J/g ≈ 434 J/g By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this declaration will result in 5 points being deducted from your report score. Signature: Note: All sections of this report must be typed Help with Formulas in Excel In Excel type "=average(range of values)" but instead of entering a range, just click at one end of the values and drag mouse to the other end. For standard deviation, in Excel type "=stdev(range of values)". C: Enthalpy of Neutralization of HCl and NaOH NaOH Concentration 0.50 M Volume Used 40 mL HCl Concentration 0.50 M Volume Used 40 mL Run 1 Run 2 Ccal(Average), J/oC 446 446 Tinitial (HCl), ˚C 25.0 25.1 Tinitial (NaOH), ˚C 24.2 24.2 Tinitial (average), ˚C 24.6 24.7 Tfinal , ˚C 28.0 28.0 ∆T, ˚C 3.40 3.35 * (a) Moles H2O formed in reaction 0.020 0.020 * (b) q (J) (magnitude of heat gained/lost ) 1,520 1,490 * (c) ∆H neutralization (kJ/mol) -75.9 -74.8 -75.3 6 pts 0.788 D: Enthalpy of Neutralization of Acetic Acid and NaOH NaOH Concentration 0.50 M Volume Used 40 mL Acetic acid Concentration 0.50 M Volume Used 40 mL Run 1 Run 2 Ccal(Average), J/oC 446 446 Tinitial (acetic acid), ˚C 25.0 25.0 Tinitial (NaOH), ˚C 24.4 24.4 Tinitial (average), ˚C 24.7 24.7 Tfinal , ˚C 28.0 28.0 ∆T, ˚C 3.30 3.30 Moles H2O formed in reaction 0.020 0.020 q (J) (magnitude of heat gained/lost ) 1,470 1,470 ∆H neutralization (kJ/mol) -73.7 -73.7 -73.7 0.0 E: Enthalpy of Hydration of Magnesium Sulfate Run 1 Run 2 Ccal(Average), J/oC 446 446 Mass MgSO4 added, g 4.55 4.55 * (a) Moles of MgSO4 0.0378 0.0378 Tinitial, ˚C 26.0 26.5 Tfinal , ˚C 34.1 34.5 ∆T, ˚C 8.10 8.00 * (b) q (J) (magnitude of heat gained/lost ) 3,620 3,570 * (c) ∆H solution (kJ/mol) -95.7 -94.5 -95.1 5 pts 0.823 Run 1 Run 2 Ccal(Average), J/oC 446 446 Mass MgSO4 ∙7 H2O added, g 10.3 10.2 Moles MgSO4 ∙7H2O 0.0418 0.0414 Tinitial, ˚C 26.5 26.6 Tfinal , ˚C 24.7 25.0 ∆T, ˚C -1.80 -1.60 q (J) (magnitude of heat gained/lost ) 804 714 ∆H solution (kJ/mol) 19.2 17.2 18.2 Standard Dev 1.41 * (d) Enthalpy of Hydr [Show More]

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