Droplet Freeze Experiment

By: Alexa Otto

Last Edited: June 5, 2018

1. Attach Thermocouple to copper plate which is attached to cooler making sure that the thermocouple has full contact with the corner of the plate (I used electric tape to tape the wire to the cooler handle and bent the open wire so that it contacted the plate.

2. Place the cooler with copper plate and thermocouple into freezer making sure to leave the end of the thermocouple that connects to the meter out of the freezer.

3. Check through the window of the freezer to make sure the thermocouple is still in contact with the copper plate. To do this use your phone light or a light source and shine it directly above the thermocouple in the window. There should be no shadow below the thermocouple if it is fully touching.

4. Allow the copper plate and cooler to cool overnight in the freezer. Have the freezer set to -20 degrees celcius.

5. When you want to do an experiment, take the cooler out of the freezer being careful not to bump the thermocouple out of place.

6. Connect the theromcouple to the meter and allow the temperature of the plate to rise above 0 degrees celcius.

7. Once the copper plate has warmed, take a kimwipe and some petroleum jelly and coat the surface of the copper plate. It will take some maneuvering to get an even coat. Be generous you need a thick coating but a flat coating.

8. To prepare your samples, use glass beakers that have been cleaned out with isopropyl alcohol and kimwipes.

9. To place the samples on the plate, use glass pipettes that have been rinsed out with isopropyl alcohol as well.

10. Once your plate is prepped you can place the samples onto the plate. In the experiment that was conducted, I placed ten drops of each sample onto the plate.

11. Place the apparatus back into the freezer being very careful not to bump the thermocouple or disturb the droplets leaving the meter end of the therocouple connected and on top of the freezer.

12. Illuminate the inside of the freezer by using a phone light or some other light source placed on the top of the window.

13. Carefully watch the droplets from the window on top of the freezer. Once one droplet freezes note which droplet it was and what temperature it was at.

14. After all the droplets are frozen, take the mean of the temperatures

15. Remove the apparatus from the freezer and warm the plate up with a hair dryer until it is warm enough to wipe the surface clean with kimwipes and isopropyl alcohol.

Below is a picture of frozen droplets but also the setup of the cooler, plate and thermocouple.