Making YOU the Scientist: Freezing Point Depression and Phase Changes

This is a great activity for sparking student’s interest in science and for introducing two important physics topics: freezing point depression and the phases of matter.

You can do this lab in almost any setting: in the classroom, during home schooling, as an online learning demonstration or just a fun thing to do with the kids on the weekend. Kids love playing with water and ice and the results of the experiment can be seen in just a few minutes. My middle school students always enjoy this activity. You probably have everything you need at school, around the house or you can get what you need with a quick trip to the grocery store.

A full demonstration of this experiment is available on my Step by Step Science YouTube channel. Link to the video: https://youtu.be/8e7JNVDekVU

Included is a worksheet with instructions that will guide your participants through this experiment.

First, you will lower the freezing point of water to below zero degrees celsius using ordinary table salt (sodium chloride). After lowering the freezing point of the ice water mixture to below zero degrees celsius, students will place a test tube with water and a thermometer in the beaker. Then they will measure the amount of time it takes for the water in the test tube to freeze. This should take about 5 to 10 minutes. Something my students always find quite amazing.

I hope you and your students have fun with freezing point depression and phase changes.

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