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
... [Show More] 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 = -CcalT = -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
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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 Less]