MS-PS1-6: Thermal Energy Design

MS-PS1-6
Thermal Energy Design

Middle School

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Learning Objectives

• Define and compare exothermic and endothermic chemical reactions based on energy release or absorption.

• Describe how to track thermal energy transfer as it flows through a system.

• Identify and apply design criteria and constraints when creating or evaluating a solution.

• Explain how testing and modifying a design leads to the best possible solution.

Key Vocabulary

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Exothermic Reaction

An exothermic reaction is a chemical process that releases energy, usually in the form of heat.

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Endothermic Reaction

An endothermic reaction is a chemical process that absorbs energy from its surroundings, often feeling cold.

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Thermal Energy

Thermal energy is the total energy of moving particles in an object, which we feel as heat.

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System

In science, a system is a specific group of interacting parts that are being studied together.

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Reactants

Reactants are the starting substances that are present at the beginning of any chemical reaction.

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Products

Products are the new substances that are formed as a result of a chemical reaction.

Key Vocabulary

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Design Criteria

These are the specific requirements, or goals, that a design must achieve to be successful.

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Design Constraints

These are the limitations or challenges, such as time and materials, on a design project.

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Combustion

Combustion is a chemical reaction that occurs between a fuel and an oxidant to produce heat.

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Exothermic vs. Endothermic Reactions

Exothermic Reactions

• This type of reaction releases thermal energy, causing the surroundings to feel warmer as a result.

• Energy is transferred from the reaction to the environment, which you can often feel as heat.

• A common example of an exothermic reaction is the process of combustion, like a burning fire.

Endothermic Reactions

• This type of reaction absorbs thermal energy, causing the surroundings to feel colder as a result.

• Energy is transferred from the environment and is absorbed into the chemical reaction itself.

• A practical example is a chemical cold pack, which gets cold after being activated for use.

Multiple Choice

What is the main characteristic of an exothermic reaction?

• It absorbs thermal energy, causing the surroundings to feel colder.

• It releases thermal energy, causing the surroundings to feel warmer.

• It does not involve any change in thermal energy.

• It converts thermal energy into light energy.

Multiple Choice

What is the key difference in how energy is transferred in endothermic and exothermic reactions?

• Endothermic reactions release energy to the environment, while exothermic reactions absorb it.

• Exothermic reactions transfer energy to the environment, while endothermic reactions absorb energy from it.

• Both reactions absorb energy from the environment, but at different rates.

• Both reactions release energy to the environment, but in different forms.

Multiple Choice

When a powder is mixed with water in a beaker, the beaker becomes noticeably warmer. What can you conclude about this process?

• It is an endothermic reaction because it is absorbing heat.

• It is an exothermic reaction because it is releasing heat.

• It is an endothermic reaction because it is releasing heat.

• It is an exothermic reaction because it is absorbing heat.

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Exothermic Example: Combustion

• A combustion reaction is a burning process that always uses oxygen (O₂) as a reactant.

• ​Reactants, like wood and oxygen, rearrange to form new products like CO₂ and H₂O.

• This releases energy as heat and light: Wood + O₂ → CO₂ + H₂O + Energy.

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Multiple Choice

What is the definition of a combustion reaction?

• It is a process that creates oxygen.

• It is a burning process that uses oxygen.

• It is a reaction that absorbs heat and light.

• It is a process that only involves liquid reactants.

Multiple Choice

What happens to reactants like wood and oxygen during a combustion reaction?

• They are completely destroyed and vanish.

• They are rearranged to form new substances like carbon dioxide and water.

• They are converted into pure energy with no new substances formed.

• They are cooled down by oxygen to produce smoke.

Multiple Choice

Based on the chemical equation 'Wood + O₂ → CO₂ + H₂O + Energy', what can be concluded about this combustion reaction?

• The reaction released energy in the form of heat and light.

• The reaction must have used nitrogen as a reactant.

• The reaction created more reactants than it started with.

• The reaction absorbed energy, making the surroundings colder.

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Fireworks: Combustion in Action

• Fireworks are a real-world example of an exothermic reaction.

• The fuse ignites the black powder fuel, starting a planned combustion reaction.

• Combustion releases heat, light, sound, and motion to create the spectacular display.

• Carefully planned reactions produce safety and visual effects.

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Multiple Choice

When a firework ignites, the fuel reacts with oxygen and produces heat, light, and sound. Which type of chemical reaction is this?

• Endothermic

• Exothermic

• Neutralization

• Precipitation

Multiple Choice

What causes the spectacular display of light and sound from a firework?

• The speed at which it travels through the air.

• The planned combustion of its fuel.

• The sound of the initial launch.

• The heat from the lit fuse alone.

Multiple Choice

Based on the sequence of events, what would most likely happen if a firework's lit fuse failed to ignite the black powder fuel?

• The firework would explode immediately on the ground.

• The firework would launch but without a final display.

• The firework would not launch into the air.

• The firework would silently launch into the air.

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Defining Success: Criteria & Constraints

Criteria

• Criteria are the requirements a design must meet to be considered successful.

• They describe the necessary features or functions the solution must have.

• For example, a hand warmer must heat to 100°F in less than a minute.

Constraints

• Constraints are the limitations or challenges that restrict the design process.

• These often include the total cost of materials, time, and safety rules.

• Engineers must work within these limits to find a successful solution.

Multiple Choice

Which statement best defines criteria and constraints in the design process?

• Criteria are requirements for success, while constraints are limitations on the design.

• Criteria are limitations on the design, while constraints are requirements for success.

• Criteria describe the cost of materials, while constraints describe the necessary features.

• Criteria are optional suggestions, while constraints are the main goals of the project.

Multiple Choice

What is the relationship between criteria and constraints in an engineering project?

• To list the problems with a design after it has been built.

• To set the goals for the solution while also defining the project's limits.

• To focus only on how much the solution will cost and how long it will take.

• To provide a list of materials that cannot be used in a design.

Multiple Choice

Which of the following is an example of a design criterion?

• The hand warmer must cost less than $5

• The hand warmer must reach 100°F in under 1 minute

• The hand warmer must be red in color

• The hand warmer must be shaped like a square

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The Iterative Design Process

• First, identify and research the problem to understand its criteria and constraints.

• Brainstorm multiple ideas and create a design for the most promising solution.

• Build a model of your solution, called a prototype, and test its performance.

• Analyze test results and repeat the cycle to improve and optimize your design.

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Multiple Choice

What is the primary goal of the iterative design process?

• To improve a solution by repeating a cycle of building, testing, and analyzing.

• To create a final product on the very first attempt.

• To choose a problem that is easy to solve quickly.

• To build a prototype that never fails its tests.

Multiple Choice

What is the specific function of building a prototype in the design process?

• To create a testable model of the proposed solution.

• To identify the initial problem and its constraints.

• To brainstorm as many different problems as possible.

• To analyze the results from a previous design cycle.

Multiple Choice

A design team builds a prototype to solve a problem, but it fails during testing. What is the most logical next step for the team to take?

• Analyze the test results to understand the failure and then brainstorm new ideas.

• Build the exact same prototype again and hope it works the second time.

• Abandon the project and find a completely new problem to research.

• Immediately start building a model for a different, unrelated idea.

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Engineering Practices in Thermal Energy Design

• Engineers ask questions to understand the problem, requirements, and limitations, like designing a hand warmer or cold pack.

• They build small prototypes to test how well the device releases or absorbs thermal energy.

• Engineers plan tests to measure temperature changes and how fast energy is transferred.

• They analyze test results to see which design works best and meets criteria.

• Engineers share their findings and suggest improvements to make the device safer and more effective.

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Multiple Choice

Why do engineers ask questions before designing a hand warmer or cold pack?

• To unnecessarily make the project take longer

• To understand the problem, requirements, and limitations

• To avoid building a prototype

• To skip testing

Multiple Choice

What is the purpose of building a small prototype of a thermal energy device?

• To test how well it releases or absorbs thermal energy

• To create a final product immediately

• To only focus on its appearance

• To avoid measuring temperature changes

Multiple Choice

How do engineers use the results from testing thermal energy devices?

• To stop the design process

• To choose materials randomly

• To avoid sharing findings with the team

• To compare designs and improve the device

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Engineering Practices in Thermal Energy Design (Part 2)

• Engineers use math to analyze data from a thermal energy device, such as temperature changes and energy transfer.

• The core task is designing solutions that meet criteria (like target temperature and safety) within given constraints (like materials, cost, or time).

• They use evidence-based arguments to compare different designs and determine which works best.

• Engineers must clearly communicate findings and evaluate information from tests and research to improve the device.

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Multiple Choice

Why do engineers use math when testing a thermal energy device?

• To make the project take longer

• To analyze data like temperature changes and energy transfer

• To avoid building prototypes

• To decorate their reports

Multiple Choice

What is the main task of engineers when designing a thermal energy device?

• To create the most complex design possible

• To prove that their first idea is always the best

• To meet criteria like target temperature and safety within given constraints

• To make sure that all team members agree on one idea

Multiple Choice

An engineer has two different designs for a new thermal energy device. To choose the best one, what is the most critical step the engineer must take?

• Choose the design that uses the most complicated math equations

• Select the design that was suggested by the most experienced engineer

• Analyze data on how each design meets the project's criteria and constraints

• Build both designs and see which one the public likes more

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Common Misconceptions

Misconception	Correction
Things 'disappear' when they burn.	Atoms are rearranged into new products like gas and ash, not destroyed.
Chemical reactions only produce heat.	Some reactions release heat (exothermic), while others absorb it, feeling cold (endothermic).
Engineering is only about building things.	Engineering is a problem-solving process involving research, design, testing, and communication.

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Summary

• Chemical reactions can be exothermic (release energy) or endothermic (absorb energy).

• Combustion is a common exothermic reaction that requires oxygen.

• The Engineering Design Process is a cycle of testing and modifying to improve solutions.

• A successful solution meets all defined criteria and stays within its constraints.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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• 4