Name: ________________________ Date: _____________________ Block: __________

Endo & Exothermic Process Uses: Hot & Cold PacksEngineering Design Process:

Request for Proposal:

Southridge High School’s Athletic Trainer is accepting bids up until May 22nd, 2015, to create, test, and evaluate replacement hot and cold packs for first aid kits that are taken out to athletic events. As employees of Skyhawk Engineering, Inc., you are being asked to develop a new hot or cold pack and to propose your product highlighting its strengths and weaknesses using several tests. In order for your plan to be considered, it must adhere to the following criteria and constraints:

1) The contents of your pack must fit in a 6.5” x 3.25” plastic sandwich baggie.

2) The pack and all of its contents may not exceed 300 grams.3) Each pack is currently purchased for $1.50. In order for your proposal to

be considered, you will need to keep your costs of making the pack below this amount to allow for the maximum profit margin for the school.

4) The pack must reach a temperature range of 120°-160°F for exothermic reactions and 37°-41°F for endothermic reactions.

5) The pack must stay warm or cold for 20 minutes. 6) The contents of the pack must be safe, according to MSDS, to come into

contact with skin and for disposal purposes.

Engineering Portfolio for the Hot/Cold Pack Project Chemistry: Engineering Project Portfolio 1Endo & Exothermic Process Uses: Hot & Cold Packs

Identify the Problem Generate Solutions Test Solutions Analyze Results

Identify the ProblemExplain the relevant science concepts that need to be considered in solving this problem:

1) First Law of Thermodynamics, because

2) System and its surroundings, because

3) Endothermic processes, because

4) Exothermic processes, because

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

Substance: __________________________ Energy Diagram: Word Description:

Substance: __________________________ Energy Diagram:

Substance: __________________________ 2

5) Heat Capacity and specific heat, because

6) *Enthalpy (Heat of solution), because

7) *Hess’ Law because

8) Material Data Safety Sheet (MSDS) because

9) Research the MSDS for each chemical that you can possibly use for your hot or cold pack. List the health and environmental concerns for each chemical including whether or not the chemical reacts with plastic.

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

Energy Diagram: Word Description:

Substance: __________________________ Energy Diagram:

3

What is the problem you are engineering a solution for?

What are the criteria and constraints you face in creating your hot or cold pack?

1)

2)

3)

4)

*5

Expense Report:All hot and cold packs will need to be contained in a 6.5” x 3.25” plastic sandwich bag. In addition, the chemical used will need to be contained in a smaller plastic baggie to be placed within the sandwich bag. These are costs that every group will incur. Plastic Sandwich Baggie : $0.03Small Chemical Containment Bag: $0.03The decisions about other ingredients will be left to each group. The choices are:

Substance Cost Substance CostAnhydrous CaCl2 $0.03/g NaOH $0.05/gKNO3 $0.05/g NH4NO3 $0.03/gDistilled water(Density of water is 1 g/mL)

$0.0003/mL 2” x 3” chemical containment bag $0.03

6.5” x 3.25” plastic sandwich bag $0.03

Generate Solutions:In your group, develop two detailed prototypes to consider, including the total cost of each. Underneath, list the pros and cons of each prototype. You will need to research the MSDS sheets for each chemical to see how toxic they are, should the baggie fail and leak the contents as well as if it is a good idea to store them in plastic.

Example Prototype Name: Sica’s Drop it Like It’s Hot Pack

Use the specific heat equation (ΔH = specific heat � g � ΔT) to determine the amount of energy that will be absorbed or released when you aim to reach a specific temperature change. Be sure to convert to Kelvin before calculating your amounts.ΔT of 65->130°F = (5/9�(65-32))+273 = 291 K; (5/9�(130-32))+273 = 327 K; ΔT = 327-291 = 36 K ΔH = (4.18 J/g-K)(200 g H2O)(36 K)ΔH = 30,096 J = 30 kJ

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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Use this value along with our experimental heats of solution or reaction to determine how many moles and grams you will need for your hot/cold pack. 39 kJ/mol = 30 kJ/xx = 0.77 mol anhydrous CaCl2 x 111 g CaCl2 / 1 mol CaCl2 =85.5 g CaCl2

These calculations will help determine you expenses:Details Cost

Sandwich bag 6.5” x 5.5” $0.03

85.5 g anhydrous CaCl2 $0.03/g $0.86

200 mL of distilled water $0.0003/mL $0.06

Chemical containment plastic bag 2” x 3” $0.03

$

$

$

Total $ 0.98 / pack

Pros Cons

Allows for about a $0.50 profit.

CaCl2 is also used to salt sidewalks and roads

and is relatively safe for household use.

Simple to manufacture because there are only

two ingredients.

Can be disposed in trash.

Can irritate skin and eyes if it leaks.

Requires two baggies so that the cooling will not

occur until the desired time.

Requires a large amount of salt and water.

1. Prototype “A” Name:__________________________________

Use the specific heat equation (ΔH = specific heat � g � ΔT) to determine the amount of energy that will be absorbed or released when you aim to reach a specific temperature change.

Use this value along with our experimental heats of solution of reaction to determine how many moles and grams you will need for your hot/cold pack.

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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These calculations will help determine you expenses:Details Cost

$

$

$

$

$

$

$

Total $_______/ pack

Pros Cons

2. Prototype “B” Name:__________________________________

Use the specific heat equation (ΔH = specific heat � g � ΔT) to determine the amount of energy that will be absorbed or released when you aim to reach a specific temperature change.

Use this value along with our experimental heats of solution or reaction to determine how many moles and grams you will need for your hot/cold pack.

These calculations will help determine you expenses:Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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Details Cost$

$

$

$

$

$

$

Total $_______/ pack

Pros Cons

Look over your two prototypes, including the pros and cons of each. In your group, decide which prototype you would like to build.

In the space below, explain which prototype you will make (include the name) and why (include why this is your best prototype, based on the criteria and the constraints):

Example: The prototype selected was Sica’s Drop it Like It’s Hot Pack because it is a simple pack to make due to the fact that it only requires two ingredients, anhydrous calcium chloride and distilled water. Since only two ingredients are needed, they are required in large quantities (85.5 g of CaCl2 and 200 g of H2O) but fortunately cost very little per unit. CaCl2 is only 1 cent per gram while distilled water is very inexpensive at 3/10 of a cent. This means that the most expensive ingredient will be the salt at a total price of $0.86. The salt and water must be separated during storage by two different baggies so that they will only be activated by squeezing when the need for a hot pack arises. This will cost a minimal amount of 6 cents. Calcium chloride is relatively safe should a puncture in the bag occur, the salt can easily be removed from skin by washing the area immediately. No special disposal of this pack is necessary as it can be placed in any trash container. The most adverse effect it could have if it got into the soil would be to make the soil hypertonic and would prevent surrounding plants from taking up water, causing them to die. This is often seen on the side of roads that have been salted in the winter with CaCl2 to prevent ice build up.

The prototype selected is_______________________________________________________________________________

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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because ___________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

___________________________________________________________________________________________________

__________________________________________________________________________________________________ .

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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Test

Solutions: Temp vs. Time TestYou will need to continuously monitor the temp of the reaction/solution over a period of 20 minutes. To do this you will use

the Vernier temperature sensor and LabQuest. Place the temperature probe directly into your plastic baggie and seal

around it to the best of your ability.

– To adjust time intervals tap on the “Mode” box on the meter screen and enter 300 for the interval and 1200 for the

duration.

– To change the units to °F, tap on the red box on the meter screen, select “change units,” and then °F.

Title:______________________________________________________

Did your hot/cold pack reach its

desired temperature range?

How quickly did it reach the maximum or minimum temperature?

How long did it hold this temperature?

How does yours compare to other groups in this class?

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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Time 0 min 5 min 10 min 15 min 20 min 25 min 30 min

Temp (°F)

Analyze Results: Proposal SummaryBased on prototype development and prototype testing (temperature vs. time test), Skyhawks Engineers propose the hot/cold pack design described below for your consideration.

Prototype / Expenses / Potential Profit:Prototype Proposed:_________________________________________________________________________________Total $_______/ hot/cold pack

Profit $_______/ hot/cold pack

Test Results Summary:

Skyhawks Engineering Inc.’s _______________________ hot/cold pack is the best replacement product for the portable

first aid kits because__________________________________________________________________________________

__________________________________________________________________________________________________ .

The strengths of this hot/cold pack are____________________________________________________________________.

The data (initial or final test results) demonstrate these strengths because________________________________________

__________________________________________________________________________________________________ .

The weaknesses of this hot/cold pack are_________________________________________________________________.

The data (initial or final test results) indicate the weaknesses of this design because_________________________________

__________________________________________________________________________________________________.

Future modifications that might be made to the original design would be__________________________________________

___________________________________________________________________________________________________

because____________________________________________________________________________________________

__________________________________________________________________________________________________ .

These modifications would make the product more successful because___________________________________________

__________________________________________________________________________________________________ .

If the athletic trainer buys 40 hot and 40 cold packs per year to keep the portable first aid kits stocked at SRHS, what is the total potential profit that SRHS could realize if they selected your product and put towards other expenses?

___________________________________________________________________________________________________

__________________________________________________________________________________________________ .

If this product is successful, other high schools in the local are might consider buying their product from you also. What limitations and challenges might you face as a small business owner in trying to meet the needs of this order long term as the demand rises and grow your business (Ex: space to make the pack, time it takes to assemble, supplies needed to make the packs, hiring employees)?

___________________________________________________________________________________________________

___________________________________________________________________________________________________

__________________________________________________________________________________________________.

Chemistry: Engineering Project Portfolio *Required for mastery.Endo & Exothermic Process Uses: Hot & Cold Packs

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