Temperature Controller Lab: Part II
Description: Melt a piece of gallium using the temperature controller in part I. Then mix the gallium with a seed crystal and melt it again. Measure and compare the freezing times in each case.
Materials:
- Gallium
- Magnesium oxide tablets
- Temperature controller from part I
Procedure:
- Segment off a small piece of gallium. You may need to heat up a bowl of water and place the vial of gallium in it first.
- Leave the hot plate turned off. Place the piece of gallium on the plate. Make sure that it is fully solid. Gallium can melt at room temperature, so make sure you are in a room that is sufficiently cool.
- Set the temperature of the controller to 32C. Gallium melts around 29-30C, so the gallium should melt. Turn off the controller and time how long it takes for the gallium to solidify. This may take hours.
- Grind up magnesium oxide tablets. The magnesium oxide will serve as the seed crystal. Melt the gallium again and mix it with the magnesium oxide powder. Wait for it to solidify.
- Set the temperature of the controller to 32C again. After the gallium melts, shut off the controller and time how long it takes for the gallium to freeze.
- Compare the freezing times in each case.