Sodium Chloride Lab

The purpose of this report is determine if sodium chloride is a viable option as a deicer on winter roads. To determine this, one must compare a multitude of factors. In this lab, the freezing point depression of water, enthalpy of dissolution, cost, and environmental impact will be discussed. A large factor in how effective a substance is as a deicer is it’s ability to decrease the freezing point of water. If the freezing point of water can be lowered, the outside temperature must be much colder to reach this new freezing point, resulting in less ice on the roads. These results a somewhat inaccurate due to the fact that when the solutions were actually freezing is difficult to tell. Some solutions froze slowly and showed a plateau, while others

Once dissolved in water, sodium chloride can be very corrosive. Sodium chloride is what causes rust to form on cars, and greatly wears down the driving surfaces of roads and bridges. All of the sodium chloride spread on the roads eventually makes its way into water sources. The concern is the chloride in sodium chloride, chloride is big contaminant for water. Sodium chloride is also a threat to soil. Sodium chloride is known to break down soil structure and cause stress to the roots of plants.

Although a large harm to the environment, sodium chloride is the cheapest option for road deicers. Other deicers like magnesium chloride, calcium chloride, and potassium chloride range anywhere from $111 to $208 per metric ton. Their environmental concerns are not quite as concerning as sodium chloride, but sodium chloride only costs about $42 per metric ton.4

Besides the inaccuracy in determining the freezing point and problems in the enthalpy of dissolution, the largest source of error was the temperature probe. Over the course of the multiple trials, the temperature probe would read somewhat inconsistent values. Due to this uncertainty, trials were performed on pure deionized water to see how far the probe read from zero degrees Celsius. Another source of error was in the calorimeter. Using two foam cups as a calorimeter is sufficient, although far from perfect. Using a bomb calorimeter would be much more accurate. Even calculating the calorimeter constant through experiment and taking this into account, this was still a large source of error.

EXTENSION OF WORK:
The article published by the Minnesota Pollution Agency, describes how salting the roads negatively impacts the environment. The article states that sodium chloride erodes the driving surface and the metal on vehicles. The chloride in sodium chloride also pollutes ground water, lakes, and streams1. Due to these infrastructure and environmental concerns, a possible extension of work could be the study of alternative compounds or methods in making roads safer – while still keeping costs