Hand Warmers
Project Overview
For this project, we learned the science of handwarmers. The requirements were that the warmers (or coolers) had to have a 20 degree Celsius difference and we had to use a salt and water. During this project, we had a competition and it was whatever group made the best hand warmer, all the Chem classes would make 100 of them for the student store and sports events. There were four judges during the presentation and they were Mrs. Vogl, Mr. Philpot, Mr. Moore, and Mrs. Davis. The labs we did for this project were based on finding out which salt was the best for the group.
Data/ Analysis
Before we actually started planning and making our hand warmers, we had to learn about specific heat and heat capacity. We learned about the formula Q=mcΔt; where Q is the amount of heat energy gained or lost by substance, m is the mass of the substance,c is the specific heat, and Δt is the change of temperature. After learning about this, we did a lab where we practiced with a coffee cup calorimeter. We used magnesium sulfate hydrate and we tested what the temperature change was for the salt. My group found the temp change was only about 4 degree addition. After doing this, we used the calorimeter to test 8 different salts to see which had the closest temperature change to 20 degree. After doing this lab, we chose to use lithium chloride because it was the closest. After figuring out the salt, we needed to brainstorm what our design was going to be. As you can see from the slideshow, our ideas ranged from being panda shaped to a rectangle shape with a naugahyde cover. After making the hand warmer, we tested it to see how long the heat lasts with the cover and it lasted about 12 minutes.
The Science Behind Our Hand Warmer
To get the warmer hot, we mixed lithium chloride salt and water together to start the reaction. The reaction is exothermic, so that is why it heats up. When we mix up the mixture, the salt dissolves and the water molecules surround the positive and negative ions, breaking the salt apart. The positive charge in the water takes the negative ions in the salt, and the negative charge goes to the positive ions. This is how the reaction starts and why the salt dissolves in the water.
Conclusion
This project was not that fun because there wasn't anything big about it. The thing that made it worth it was the competition aspect of it, even though my group didn't win. A thing that went poorly was that since most of the class was using lithium chloride for their salt, we ran out of it for a couple of days, and so my group couldn't do anything until it got replenished. A thing that went well was how well our group worked together. From this lab, I learned why salts dissolved in the water and how to make homemade hand warmers if it gets cold enough. To be better, I could have thought of more ideas for the design and been in charge more. I didn't like this project because we did the same thing over and over again. So I put this project down as one of the less exciting ones that I have done in my STEM career.