Summer Research Program for Science Teachers

Partners in Science Program



Judith Exler

Norman Thomas High School

August 2003



How does adding a solute affect the freezing point of a solvent?



Objectives:  1. Students will be able to devise and carry out an experiment.

2. Students will learn how covalent and ionic substances affect the freezing points of water and why.

3. Students will practice their graphing skills.


Students are given the task of designing an experiment that examines the effects of various solutes on water. The length of time for this lab is 40 to 45 minutes. Students are to write up their experiment in the following manner.


Hypothesis- How do you think your solutes will affect the freezing point of water. Which do you expect to have the most effect? Which do you expect to have the least effect?


Materials and method- The following materials are available: chemistry books, beakers, scale, ice cubes, thermometers, graduated cylinders, sugar, sodium chloride, and calcium chloride.

You are to set up an experiment to test the affect of your various solutes on the freezing point of water. Be sure to state how much water, solute, and number of ice cubes you put into each beaker. Remember to include a control. You will need to graph at least 5 data points for each variable.


Results- The results should be shown in the form of a graph as well as a brief written summary.


Discussion- Your discussion must explain how the freezing point was expected to have changed due to the number of solute particles present in the solution (colligative properties). How could one determine the number of solute particles present in your solution? Explain anything unexpected that happened in your experiment.


Conclusion Was your hypothesis correct or incorrect?


National Science Standards addressed: Grades 9-12. Content standard A, science as inquiry. Content standard B2, structure and properties of matter



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