Science Buddies: "Ask an Expert"

I am determining how the starting temperatures affects the rate of crystallization in a supersaturated sodium acetate solution—the solution used in hand warmers. I placed the hand warmer in a 20.5 degrees Celsius water bath and a 4.5 degrees Celsius water bath. The hand warmer themselves became 22 degrees Celsius and 11 degrees Celsius respectively. I hypothesized that the cooler temperature would crystallize faster. I clicked the metal disc and the reaction started. I stopped the timer when the crystals reached the top of the hand warmer and were uniform throughout. However, both temperatures occurred around fifteen seconds with no significant difference. I did two more trials by re activating it but I got the same result. Why is this happening? What should I do? Should I continue to do more trials until I obtain better data? Thank you for all the help!

This is the link to the experiment
https://www.sciencebuddies.org/science- ... p085.shtml

Hi mn12345,

From your description of your experimental results it appears that there may be little or no difference in the crystallization rate for the two temperatures you tested. It is possible that your starting temperatures (22 degrees and 11 degrees) are too close together to see an effect on the crystal growth.

You might try keeping the hand warmers in the water baths longer so that the starting temperatures are closer to the water bath temperatures. Also you might want to try a higher temperature (for example 40 degrees C).

I hope this helps and good luck with your project. Please post again if you have more questions.

A. Norman