Magnesium Chloride as a Deicer
Emily Lekah
Fall 2015
CHEM 1066
October 15, 2015
University of Minnesota
Abstract The purpose of this experiment was to evaluate magnesium chloride as a deicer. To be a good deicer, a salt must be able to lower the enthalpy when is mixed with water. This will cause an exothermic reaction and release heat. This experiment had three tests performed within it, The freezing point depression, the enthalpy of dissolution, and finding the calorimeter constant. Even though, the results in this lab had a high present of error it was found that magnesium chloride is an effective deicer because it is relatively cheap and is safer for the environment than other deicers.
Introduction …show more content…
Many places in the United States acquire a lot of snow that creates hazardous driving conditions because of the slick roads and difficulty maneuvering. About 900 people are killed by car crashes during snowfall or icy conditions.1 Snowy and icy conditions reduces the flow of traffic by up to 10% and causes about 15% of all driving accidents. Using deicers is needed to create safe driving conditions in the winter. Finding the best deicer that is cost effective and environmentally friendly is important. These deicers will be used from major highways to airport runways. Deicers with naturally occurring chemicals are currently being prefered because they tend to cause less environmental harm than synthesized unnatural deicers.2
Effective deicers have the ability to lower the freezing point and have a negative enthalpy of dissolution to melt ice. These theories were tested in the lab. The first test shows the colligative properties of intramolecular forces while the latter can be explained by the thermochemical …show more content…
This included the environmental effects on roads, and surrounding environment. The cost of the deicer was also found. This was compared to other deicers
Results
Freezing point depression:
MgCl2 (gram) ΔT (Celsius) Kf (celsius)/(molality)
1 gram -2.1 .508
3 gram -3 .359
5 gram -3.2 .241
Table 1: The ΔT and Kf compared to the MgCl2 used.
Enthalpy of dissolution:
Trial H2O (g) MgCl2(g) Ti (C) Tf (C) Qsol (J) Qtot (J) ∆H (kJ/mol)
1 20 .5 22.5 27 385 629.78 -119.95
2 20 .75 23.5 30.9 642.45 1043.39 -132.36
3 20 1 22.6 34.9 1079.69 1747.14 -166.394
4 20 1.5 23 39.1 1448.29 2320.59 -147.5
Table 2: Average enthalpy of dissolution -141.25 KJ/mol
Trial Hot H2O (mL) Cold H2O (mL) Tihot/ Ticold (celsius) Tf (celsius) q (J)
1 50 50
Table 3
Table 2 and 3: ∆T, the amount of H2O, and amount of MgCl2 used was recorded. This data helped find Q and ∆H.
Environmental effects/costs:
Deicer Price
NaCl $55
CaCl2 $155
MgCl2 $75
Table 4: Costs of MgCl2 and other deices per ton
Emily Lekah
Fall 2015
CHEM 1066
October 15, 2015
University of Minnesota
Abstract The purpose of this experiment was to evaluate magnesium chloride as a deicer. To be a good deicer, a salt must be able to lower the enthalpy when is mixed with water. This will cause an exothermic reaction and release heat. This experiment had three tests performed within it, The freezing point depression, the enthalpy of dissolution, and finding the calorimeter constant. Even though, the results in this lab had a high present of error it was found that magnesium chloride is an effective deicer because it is relatively cheap and is safer for the environment than other deicers.
Introduction …show more content…
Many places in the United States acquire a lot of snow that creates hazardous driving conditions because of the slick roads and difficulty maneuvering. About 900 people are killed by car crashes during snowfall or icy conditions.1 Snowy and icy conditions reduces the flow of traffic by up to 10% and causes about 15% of all driving accidents. Using deicers is needed to create safe driving conditions in the winter. Finding the best deicer that is cost effective and environmentally friendly is important. These deicers will be used from major highways to airport runways. Deicers with naturally occurring chemicals are currently being prefered because they tend to cause less environmental harm than synthesized unnatural deicers.2
Effective deicers have the ability to lower the freezing point and have a negative enthalpy of dissolution to melt ice. These theories were tested in the lab. The first test shows the colligative properties of intramolecular forces while the latter can be explained by the thermochemical …show more content…
This included the environmental effects on roads, and surrounding environment. The cost of the deicer was also found. This was compared to other deicers
Results
Freezing point depression:
MgCl2 (gram) ΔT (Celsius) Kf (celsius)/(molality)
1 gram -2.1 .508
3 gram -3 .359
5 gram -3.2 .241
Table 1: The ΔT and Kf compared to the MgCl2 used.
Enthalpy of dissolution:
Trial H2O (g) MgCl2(g) Ti (C) Tf (C) Qsol (J) Qtot (J) ∆H (kJ/mol)
1 20 .5 22.5 27 385 629.78 -119.95
2 20 .75 23.5 30.9 642.45 1043.39 -132.36
3 20 1 22.6 34.9 1079.69 1747.14 -166.394
4 20 1.5 23 39.1 1448.29 2320.59 -147.5
Table 2: Average enthalpy of dissolution -141.25 KJ/mol
Trial Hot H2O (mL) Cold H2O (mL) Tihot/ Ticold (celsius) Tf (celsius) q (J)
1 50 50
Table 3
Table 2 and 3: ∆T, the amount of H2O, and amount of MgCl2 used was recorded. This data helped find Q and ∆H.
Environmental effects/costs:
Deicer Price
NaCl $55
CaCl2 $155
MgCl2 $75
Table 4: Costs of MgCl2 and other deices per ton