Freezing Point Depression and Boiling Point Elevation

The Freezing Point Depression and Enthalpy of Dissolution of Different Aqueous Solutions

Akshaya Gupta

Lab Partners: Ashley Xiong, Larry Truong, Maren Symes

TA: Ang Zhao

Lab Section 1066 008

Abstract

A lab group tries to find the effectiveness of different salts to de-ice roads in the winter. The group measured the change in temperature as the solution was prepared, and plugged in the values into the correct equations to determine the freezing point depression and the enthalpy of dissolution. Calcium chloride lowers the freezing point of water and has an exothermic dissolution. The group also noticed that as the concentration of the solution, so does the change in temperature. Using the information found, the group determined that calcium chloride was indeed an effective deicer.

Introduction

Prior to this lab, it was hypothesized that a calcium chloride solution in water would effectively lower the freezing point and that it would have an exothermic dissolution. Such a salt would be an effective deicer, because it would melt the ice on the road from its exothermic dissolution and would prevent the new formed solution from freezing again. The objective of the lab was to determine if the theoretical hypotheses would match experimental values found in the lab. Knowing this would help to solve the initial problem: whether or not the salt, calcium chloride, would work as an effective, economical, and environmental friendly deicer. This information is crucial for melting hazardous icy roadways. Currently, the Midwest uses table salt, sodium chloride, to deice the roads. The state department has found that sodium chloride is the most efficient, and inexpensive salt to use. This report will go through one method to determining the freezing point and enthalpy of dissolution of a solution. Also, this report will analyze what these results mean; how these results relate to being an effective deicer.

Experimental

This lab had three parts. In the...