Introduction My group consisted of Paige, Katie, and I. We worked very hard trying to create the most unique, cost effective, quality design for our given assignment.
What are we solving? We made a cost effective hand warmer to sell through our school at the cold winter sporting events with a 20 degree temperature change. Background Chemical Choice: Calcium Chloride - an ionic compound of calcium and chlorine - highly soluble in water and is deliquescent - salt that is solid at room temperature - this is an exothermic reaction, because the combination of the two substances make heat
Questions We Asked Ourselves . How to seal without leakage . How to keep chemicals separate in packaging . What amount of salt stays warm for the longest time . What water to salt ratio is best . What type of salt works best
Developing a model We experimented with the heat sealer to find which design would work the best to keep the salt and water separated, until it was time for them to be activated. We also tried different types of salt, to see which brought us closest to the 20*C heat change. We decided that Calcium Chloride worked the best. Final Design 3.5 grams of CaCl 20 ml of water First Tests/ Collected Data We first tested 3 grams of calcium chloride with 20 ml of water, it stayed warm for a minute and 20 seconds Then we tested 4 grams with 20 grams of water, this one stayed warm for 4 minutes this raised 40 degrees This was too much heat, so we used 3.5 grams and had an almost perfect temperature change -it went from 20.3*C to 40.8*C
Calculations Enthalpy of cold water- 59,831 Enthalpy of hot water- 6568 Our qcal (enthalpy change of calorimeter)- 585.7 Calorimeter constant- 19.52 Calorimeter constant for all trials - 337.216 j/*c Total Cost Business source binder clips- $0.55 per dozen clips Heat sealer- free (provided by Vogl) Water - free CaCl-$6.55 per 500 grams… $0.04 cents for each hand warmer So it would take four dollars to produce 100 (in terms of calcium chloride) Pack of 347 bags- $20 To make 100 hand warmers it would cost $28.58 (0.28 for one) At a reasonable price we would charge $1.00, we would make a huge profit The reusable pouch would not be included it would cost $2.00 When people come back with reusable pouch the cost of hand warmer would be cut in half as “half off refill” Marketing
To make the school aware of our handwarmers, we can make announcements, informing the school and those participating in sports aware of what we are selling. We can also make flyers to hang around the school, and ask coaches to tell their teams that they will be sold. They will be sold at the snack shacks during the games. Final Product Our final product turned out to be two separate compartments. One side is filled with water and the other side is filled with Calcium Chloride. We decided to leave space at the top where when turned upside down and unclipped the salt and water will mix. Within 15 seconds the hand warmer should raise drastically in temperature and stay warm for around 4 minutes without the outer fabric. With the fabric it should stay warm form somewhere between 8-10 minutes.