Designing and Testing a Device to Thaw a Watering Station

A Carolina Essentials™ Design Challenge

Total Time: 45 mins

Prep: 45 mins | Activity: 3-4.5 hr

Physical Science

6-8

Middle School

Overview

Understanding the flow of thermal energy can be a difficult task for students, but it can be tackled through a design challenge. In this activity, students use the scenario of a habitat that must occasionally thaw its watering stations. After determining the heat released during the solvation of calcium chloride, students design, test, and improve a device to thaw and prevent freezing of watering stations. Designs are scored on how long the water remains liquid and the cost per device.

Phenomenon

Teacher demonstration

 

Pour 500 mL of water in a 1,000 mL beaker and take the temperature of the water. Activate an instant ice pack, submerge it in the beaker of water, and take the temperature of the water 5 minutes later. Ask students how the temperature change can be explained.

Essential Question

How can chemical processes be used for heat transfer?

Objective

  1. Design, test, and improve a device that can prevent the freezing of water in a watering station.

Next Generation Science Standards* (NGSS)

MS-PS1-6. Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.

Science & Engineering Practices

Constructing Explanations and Designing Solutions

Disciplinary Core Ideas

PS1.B: Structure and Properties of Matter

ETS1.B: Developing Possible Solutions

Crosscutting Concepts

Energy and Matter

Materials

Phenomenon

Product Design

Safety Procedures and Precautions

Wear gloves and safety goggles.

Teacher Preparation and Disposal

Gather supplies for the phenomenon and engineering challenge. Copy or upload student the activity guide.

 

Calcium chloride needs to be disposed of according to state and local regulations. Consult your chemical hygiene plan and SDS. Dispose of the cold pack according to package instructions.

Student Procedures

Phenomenon

  1. Pour 500 mL of water in a 1,000 mL beaker and take the temperature of the water.
  2. Activate an instant cold pack.
  3. Submerge the pack in the beaker of water.
  4. Take the temperature of the water 5 minutes later.
Guided Research: Dissociation of Calcium Chloride

  1. In a weigh boat, measure 12.0 g of calcium chloride (CaCl2 ).
  2. In the graduated cylinder, measure 100 mL of water and pour it into the beaker.
  3. Take the temperature of the water and record it in the data table.
  4. Add the CaCl2 to the beaker and stir gently with the spoon while taking the temperature.
  5. Record the highest temperature reached.
  6. Repeat the same procedure with 6.0 g of CaCl2 and 100 mL of water.
Engineering Design Project

  1. Review the project specifications.
  2. Complete the design and testing phases using the Carolina™ Engineering and Design Process Worksheet.
  3. Share your final design and data with the class.

Teacher Preparation and Tips

Phenomenon

  1. Put data in a model table so all students can see the results. You may want to record and broadcast the demonstration.
Guided Research

  1. To save time, you may want to preweigh the calcium chloride for each group.
  1. Emphasize to students to record the highest temperature reached.
  2. Stop and discuss the meaning of these results and the implications for design.
Engineering Design

  1. You may wish to print the design project worksheet for each group.
  2. Provide the cost for each material you supply. If students bring other materials, they will need to know the cost.
  3. Student information: cost of CaCl2 = $0.02/g
  4. Inform students of how you want them to present their final design. They can choose a formal written report, slide presentation, video presentation, or other medium.

Data and Observations

Answers for temperatures will vary depending on the initial temperature of the water. Generally, 6.0 g of CaCl2 should produce half of the change in temperature when compared to the 12.0 g. An increase of about 20 to 21° C for the 12 g of CaCl2 is typical

Data Table

Exothermic Reaction

Analysis & Discussion

Present your final design with supporting evidence to the class. Use the engineering worksheet and project specifications for the basis of the presentation.

*Next Generation Science Standards® is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, these products.

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