10 the freezing temperature can be determined by

10. The freezing temperature can be determined by finding the mean temperature in the portion
of the graph with nearly constant temperature.
a. Move the mouse pointer to the beginning of the graph’s flat part. Press the mouse button
and hold it down as you drag across the flat part of the curve, selecting only the points in
the plateau.
b. Click the Statistics button, .
c. The mean temperature value for the selected data is listed in the statistics box on the
graph. Record this value as the freezing temperature of pure lauric acid.
d. Click on the upper-left corner of the statistics box to remove it from the graph.
Part II Determine the Freezing Temperature of a Solution of Benzoic Acid and Lauric Acid
11. Prepare the computer for data collection.
a. From the Experiment menu, choose Store Latest Run. This stores the data so it can be
used later.
b. To hide the curve of your first data trial, click the Temperature y-axis label of the graph
and choose More…. from the dropdown list. Uncheck the Run 1 Temperature box and
click .
12. Measure out ~1 g of benzoic acid and dissolve it in your ~ 8 g of lauric acid. Record the
precise masses of benzoic acid and lauric acid . Repeat Steps 4-9.

Advanced Chemistry with Vernier
3
Using Freezing Point Depression to Find Molecular Weight
T im e
F reez ing P o in t
13. The freezing temperature of the benzoic acid-lauric acid solution can be determined by
finding the temperature at which the mixture initially started to freeze. Unlike pure lauric
acid, the mixture results in a gradual linear decrease in temperature during freezing. Follow
the steps below to analyze the graph.