DCP CE Hess s Law
Hess’s Law
Mengyuan Wu (Millie)
7 January, 14
Aim:
The purpose of this experiment is to determine the enthalpy change for the reaction:
Introduction:
It is impossible to measure the enthalpy change for this reaction directly because the process cannot be controlled. However, you can calculate this enthalpy change by using the Hess’s Law.
Pre- lab Calculations:
Calculation 1: Required Masses for Reaction
The ratio of and is required to be 1:100 for
Table 1: Calculation for Mass of Magnesium Sulfate and Water
Required Moles (mol)
Required Mass (g)
0.025
2.5
Calculation 2: Required Masses for Reaction
The ratio of and is required to be 1:93 for , because there are already 7 moles of water within
Table 2: Calculation for Mass of and
Required Moles (mol)
Required Mass (g) 0.025
2.325
Observation:
Table 3: Raw Qualitative Data from the Experiment
Reaction 1: Solution of MgSO4(s)
Mass of water (g±0.002g)
Mass of MgSO4(s) (g±0.002g)
Initial Temperature (°C±0.25°C)
Final Temperature (°C±0.25°C)
Trial 1
45.032
3.012
25.00
29.50
Trial 2
45.037
3.009
22.00
26.50
Reaction 2: Solution of MgSO4*7H2O
Trial 1
41.897
6.167
25.00
23.00
Trial 2
41.890
6.168
25.00
23.00
Table 4: Raw Quantitative Data from the Experiment
Reaction 1: Solution of MgSO4
Before
MgSO4 is a white solid powder with a mat texture
Distilled water is a clear, transparent liquid
During
MgSO4 powder slowly dissolve in water, the temperature increase during the reaction After
The mixture becomes a clear, transparent solution after MgSO4 completely dissolved in water
Reaction 2: Solution of MgSO4*7H2O
Before
MgSO4 7H2O is a clear, solid crystal
Distilled water is a clear, transparent liquid
During
MgSO4 7H2O crystal slowly dissolve in water, the temperature decrease during the reaction
After
The mixture becomes a clear, transparent solution after MgSO4 7H2O completely dissolved in water
Table 5: Uncertainties of the Apparatus
Thermometer
Mengyuan Wu (Millie)
7 January, 14
Aim:
The purpose of this experiment is to determine the enthalpy change for the reaction:
Introduction:
It is impossible to measure the enthalpy change for this reaction directly because the process cannot be controlled. However, you can calculate this enthalpy change by using the Hess’s Law.
Pre- lab Calculations:
Calculation 1: Required Masses for Reaction
The ratio of and is required to be 1:100 for
Table 1: Calculation for Mass of Magnesium Sulfate and Water
Required Moles (mol)
Required Mass (g)
0.025
2.5
Calculation 2: Required Masses for Reaction
The ratio of and is required to be 1:93 for , because there are already 7 moles of water within
Table 2: Calculation for Mass of and
Required Moles (mol)
Required Mass (g) 0.025
2.325
Observation:
Table 3: Raw Qualitative Data from the Experiment
Reaction 1: Solution of MgSO4(s)
Mass of water (g±0.002g)
Mass of MgSO4(s) (g±0.002g)
Initial Temperature (°C±0.25°C)
Final Temperature (°C±0.25°C)
Trial 1
45.032
3.012
25.00
29.50
Trial 2
45.037
3.009
22.00
26.50
Reaction 2: Solution of MgSO4*7H2O
Trial 1
41.897
6.167
25.00
23.00
Trial 2
41.890
6.168
25.00
23.00
Table 4: Raw Quantitative Data from the Experiment
Reaction 1: Solution of MgSO4
Before
MgSO4 is a white solid powder with a mat texture
Distilled water is a clear, transparent liquid
During
MgSO4 powder slowly dissolve in water, the temperature increase during the reaction After
The mixture becomes a clear, transparent solution after MgSO4 completely dissolved in water
Reaction 2: Solution of MgSO4*7H2O
Before
MgSO4 7H2O is a clear, solid crystal
Distilled water is a clear, transparent liquid
During
MgSO4 7H2O crystal slowly dissolve in water, the temperature decrease during the reaction
After
The mixture becomes a clear, transparent solution after MgSO4 7H2O completely dissolved in water
Table 5: Uncertainties of the Apparatus
Thermometer
Cited: "A Level What Happens When an Ionic Compound Dissolves in Water Energetics Lattice Enthalpy Enthalpy of Hydration Solution KS5 GCE Chemistry Revision Notes." A Level What Happens When an Ionic Compound Dissolves in Water Energetics Lattice Enthalpy Enthalpy of Hydration Solution KS5 GCE Chemistry Revision Notes. N.p., n.d. Web. 12 Jan. 2014. <http://www.docbrown.info/page07/delta2H.htm>. Kawamura, Yoko, Ph.D. "MAGNESIUM SULFATE Chemical and Technical Assessment." Diss. Ed. Madduri V. Rao, Ph.D. 2007. JECFA. Web. <http://www.fao.org/fileadmin/templates/agns/pdf/jecfa/cta/68/Magnesium_Sulfate.pdf>. "Specific Heat." Specific Heat. N.p., n.d. Web. 14 Jan. 2014. <http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/spht.html>.