The Effect of the Molality of Salts on Freezing Points of Water

Overview

Objectives/Goals I try to find out how the affect of changing molality of salts, effects the freezing point of water. This is relevant in that, today America spends millions on deicing roadways, and in my experiment i try to find an easier, cheaper way to get the same result. Methods/Materials Materials: Plastic Test tubes and rack, Beakers (50 mL), A Scale (plus or minus 0.01 g), Lab Quest and Thermometer attachment (plus or minus 0.1 degree Celsius), Standard fresh water ice, A cooler, Salt (NaCl food grade), Salt NaCl lab grade, Salt MgCl2 lab grade , Stir stick​ For my Procedure I took the salts and measured out amounts out that followed as 0.2 molality change to 10g of water that I previously measured out. I did this three times, for both salts, varying molality from 0.5 to 1.9 mol/kg. For each I observed the solution until frozen and then I recorded the results. Results My end results showed me that, in the end the Sodium Chloride was out shown by the Magnesium Chloride, as the MgCl was more effective in all of the tests at lowering the freezing points of the solution. Conclusions/Discussion After reviewing my results I can determine that they yielded the same result as other tests with freezing points and salts. As the molality rose the freezing point of the solution traveled in a downward trend. Therefore, these results fall inline with what is already known and show no drastic differences or abnormalities than what was previously known in this specific area of chemistry. In general the Magnesium chloride out preformed the Sodium chloride but economically the sodium chloride proves still the more worth it. As all three trial graphs show, as the molality of the solutions increase there is a downwards trend (lower freezing point) for the solution. This is likely due to the higher amount of ions present in the water preventing the water molecules from freezing. There is also an obvious trend between Magnesium Chloride and Sodium Chloride, Magnesium Chloride clearly has lower freezing points at all molalities on all trials.

Competition history

• CSEF 2018 Chemistry · Entry S0612

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