Chemical Reactions
Basic definition of a chemical reaction
A process in which substances interact, causing the formation of new substances with different properties.
How does heat energy transfer occur? What direction does it go.
Heat is transferred from warmer to cooler substances when molecules bump into each other.
What is an exothermic reaction?
A chemical reaction that releases heat, therefore feels warm.
Name a real-world application of a chemical reaction
Cooking, cleaning, manufacturing, etc.
What are the first steps in the engineering design process?
Identify the problem, research, brainstorm, and choose the best idea.
What is the role of products in a chemical reaction?
The substances that are formed/remain after a chemical reaction has occurred.
Describe how energy is transferred in a flameless heater. Specify which type of heat transfer occurrs.
Heat is generated by the chemical reaction, transferring energy to the food and container, through conduction
What is an endothermic reaction?
A chemical reaction that absorbs energy, therefore it feels cool.
How are flameless heaters used in emergency situations?
For heating food in areas without conventional cooking facilities.
What are criteria and constraints in a design?
Criteria are the desired elements of a design; constraints are the limitations.
What is the role of reactants in a chemical reaction?
Substances that undergo chemical change.
What type of heat transfer occurs in fluids (liquids and gasses)?
Convection
State an example of an exothermic reaction we have tested in class. Provide evidence supporting your claim.
Rootkiller and aluminum, elephants toothpaste, wool and air, etc.
Created heat, temperature increased.
Example of a chemical reaction in cooking
Baking, where heat causes chemical reactions in the dough.
Importance of prototypes in engineering
They allow for practical testing and iteration of the design.
How can we tell a chemical reaction has occurred?
Change in color, temperature, formation of a precipitate, or gas production
Radiation. The sun warming the sand, feeling heat from a campfire, etc
Provide an example of an endothermic reaction, state evidence that supports that it is endothermic.
baking soda and vinegar, ice pack, etc.
Feels cold causing a decrease in temperature.
How does the choice of materials used to create a product affect the product?
The choice of eco-friendly, recyclable, or durable materials can reduce environmental impact and improve user experience.
Materials that are hard to find make it more difficult to produce.
Materials that are more expensive cause the price of the product to increase.
How can testing and feedback improve a design?
Iterative testing leads to improvements based on real-world performance.
Explain how a flameless heater works based on chemical reactions
By a chemical reaction that produces heat when certain substances are mixed.
How does changing the amount of reactants affect energy transfer?
More reactants typically mean more energy is released or absorbed, affecting the temperature change.
What is the difference between an endothermic reaction and an exothermic reaction?
Endothermic reactions absorb heat, exothermic reactions release heat.
What were some common issues students had after the first test of our flameless heaters? How were these issues addressed in the redesign?
Most students found that their food got too hot. Many students lowered the amount of reactants and increased the amount of food.
Steps to optimize a product design
Revising designs based on testing, feedback, and reevaluation of criteria and constraints.