Matter lab · phase change

Freezing point of stearic acid

Time0 s
Temperature85.0 °C
StateAll liquid
Solid0%

A reading every 10 seconds · watch what the temperature does while the acid is turning solid

The burner is holding the stearic acid at 85 °C, well above its freezing point. Take the heat away to start.

Setup

8.0 g of stearic acid in the test tube, room air at 22 °C. Nothing about the setup changes during a run.

 

Readings

Temperature and state of the stearic acid every ten seconds
t (s)T (°C) state% solid

 

The three stages

Heat leaves the tube at much the same rate the whole way through. What changes is whether that energy comes out of the temperature or out of the freezing.

How to use this simulation

  1. Read the Setup panel to see the sample size and starting conditions, which stay fixed for every run.
  2. Use the How fast to run the 13 minutes dropdown to watch in real time or speed things up.
  3. Press Remove the heat to start cooling the tube, and watch the scene and the cooling curve update together.
  4. Watch the readouts at the top: Time, Temperature, State, and Solid track the run as it happens.
  5. Check the Readings table for a reading every 10 seconds, and the The three stages panel to see which stage (liquid, freezing, or solid) is currently active.
  6. Turn on Add reading error for realistic thermometer scatter, or Let it supercool to see the dip real samples often show before crystals form.
  7. Press Reset to run again, or Copy data to export your readings.