Science Project on the Freezing Rate of Different Types of Water

State and municipal governments frequently dispense salt as a de-icing agent on roads. It works by effectively lowering the melting temperature of the ice. This phenomenon --- known as freezing-point depression --- also provides the basis for a variety of science projects. The projects can range from simple to intricate --- complete with mathematical predictions --- depending on the grade level of the student. Furthermore, the list of required equipment includes only a sauce pan and a thermometer. Students will freeze samples of liquids recording the temperature/time periodically to see how long it takes to turn into a solid. Then they will record the temperature/time while thawing. This lesson shows factors that affect the rate at which liquid freezes. Before the experiment, have students make predictions in their science notebooks. Discuss the variables and have them record the data in their science notebooks.

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Lesson Variations

Blooms taxonomy level:

Applying

Extension suggestions:

Rearranging the equation from Step 3 would allow an experimenter to measure delta(T) and then solve for the molecular weight, MW, of sucrose. That is, MW = (-1.86 grams of sucrose) / (delta(T) kg water). In fact, many high school and college-level chemistry students conduct experiments in which they experimentally determine the molecular weight of an unknown substance. The method also works with regard to boiling points, except the value for k changes to 0.52.

References

Contributors:

Lisa Courson

Originator:

Ayers Institute for Learning & Innovation