PROCEDURE
For this project, we were given the task to design and create an effective hand warmer based on chemistry concepts we have learned in our class to sell at the student store to winter athletes and fans. Along with this we needed to try and make the product cheap, environmentally friendly, and create a temperature increase of 20* C. The first step of our project was to discover what ionic salts could effectively create heat. For this, we tested 8 different salt discovering whether or not they were endothermic or exothermic. To create heat, we would want to find a salt that has an exothermic reaction and get a temperature rise of at least 20* C. After testing the salts we decided to use lithium chloride since it created more heat than the other salts in less time but we later changed this to calcium chloride as it is much cheaper and still creates the appropriate temperature change over a longer time. After choosing our salt we needed to find a way to insulate it so it would last longer. We discovered our other ingredients of vermiculite, activated charcoal, and iron powder in response to retaining heat along with our idea of a polyester pouch to fully insulate the product to last longer. We figured out what components and ratios would benefit our product through thoughtful trial and error proving our ideas to create a better hand warmer.
CHEMIstry behind our hand warmer
Endothermic reactions - chemical reactions that absorb heat
Exothermic reactions - chemical reactions that release heat
Calcium Chloride and Water - representation of the reaction, CaCl2 (s) + H2O(l)--> Ca(+2) (aq) + 2Cl(-) + H2O(l), Calcium Chloride and Water combine in an exothermic reaction where heat is created through the separation of the calcium and chloride molecule bonds using water as its means to break down.
Vermiculite - a hydrous phyllosilicate mineral, expands when heated and contains air pockets and a very minor amount of water. In our product we used this as one of our key insulators since it has air pockets to heat up and expands creating a larger surface area to contain the heat.
Activated Charcoal - is thermally conductive, this helps in spreading the heat through out the hand warmer.
Iron Powder - is conductive, helping our product retain heat for longer.
Exothermic reactions - chemical reactions that release heat
Calcium Chloride and Water - representation of the reaction, CaCl2 (s) + H2O(l)--> Ca(+2) (aq) + 2Cl(-) + H2O(l), Calcium Chloride and Water combine in an exothermic reaction where heat is created through the separation of the calcium and chloride molecule bonds using water as its means to break down.
Vermiculite - a hydrous phyllosilicate mineral, expands when heated and contains air pockets and a very minor amount of water. In our product we used this as one of our key insulators since it has air pockets to heat up and expands creating a larger surface area to contain the heat.
Activated Charcoal - is thermally conductive, this helps in spreading the heat through out the hand warmer.
Iron Powder - is conductive, helping our product retain heat for longer.
REFLECTION
Overall, This project went very well as we were abele to complete the main task of creating an effective hand warmer using chemistry concepts and demonstrating a temperature change of at least 20* C. We went through a few different models of our hand warmer initially staring with a balloon exterior, then to plastic freezer bag with lithium chloride, and finally settled on the calcium chloride solution in the plastic freezer bag with a polyester case around it. Through out the creation of our product, we tweaked many parts of the solution and mixture to be both cost effective and create a long lasting product. Despite our effort put into creating our had warmer, ours wasn't the best environmentally, only the outer case was reusable, and it wasn't extremely cheap, so we found a way to sell our product to make an appropriate profit basing our product on a business standpoint. We would sell the product in different ways to make more money and continually make a profit from people needing to buy refills. Even though we would have liked our product to be environmentally safe by being reusable we discovered that wasn't totally possible with our prototype and instead focused on the money aspect to raise funds for our schools sports programs and STEM program. During this project, we learned about using exothermic reactions to create heat and recapped on thermodynamics to retain as much heat as possible. If we were to do this project again I would have liked to spend more time trying to find ways to make our product more environmentally safe to accomplish more aspects of the project. In the end, our project was a success as we completed our task but if we had more time or resources we could have improved a few aspects of our latest prototype.