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Learning Interchange
Units of Practice

Lesson #6: Limiting Reactants and Percent Yield

Lesson Details


Subject: Science
Learning Level: High School
Author(s): Geri Anderson-Saxton, Melissa Chardeen
Submitted by:

Abstract

This lesson will introduce students to the concept of limiting and excess reactants (too little of one reactant; too much of another). Additionally the students will be introduced to % yield: the concept that the actual amount of product made may be different from the theoretical calculations. These are covered in class and then the students use this knowledge to modify their recipes and "mass produce" their product.

Lesson fundamental understandings:
Essential Questions:

1. Do I have any "leftovers" in my chemical process? If so, what is left? Can I rework my "recipe" to avoid these leftovers?
2. What is the % yield for my "recipe"? How do I have to adjust my recipe to make enough product?

Standards

National Standards

Scientists conduct investigations for a wide variety of reasons. For example, they may wish to discover new aspects of the natural world, explain recently observed phenomena, or test the conclusions of prior investigations or the predictions of current theories. * Mathematics is essential in scientific inquiry. Mathematical tools and models guide and improve the posing of questions, gathering data, constructing explanations and communicating results. * Scientific explanations must adhere to criteria such as: a proposed explanation must be logically consistent; it must abide by the rules of evidence; it must be open to questions and possible modification; and it must be based on historical and current scientific knowledge.

State Standards

Nevada: 20.12.4 Compare groups of data, taking into account both percentages and actual numbers 22.12.1 Analyze experimental procedures and suggest appropriate revisions for improvement 23.12.2 Use algebraic equations when appropriate 23.12.5 Trace the source of differences between an estimate and the calculated answer that exceeds agreed-upon standards for precision 24.12.5 Write procedures for investigation of delegated or original scientific problems


Lesson

Prerequisite Skills

Content Area Skills: 1. naming compounds and writing formulas 2. writing and balancing equations 3. determining molar mass of compounds 4. converting grams to moles and moles to grams Laboratory Skills: 1. massing chemicals with proper significant figures 2. using measuring tools 3. use of bunsen burner (some projects) 4. use of thermometers (some projects) 5. familiarity with basic safety rules and procedures

Teacher Information/Situations/Setting/Time

Class Activity and Guided/Independent Practice: 45 min
Application Lab: 45 min
Task #5 (Analysis & Mass Production of Product): 2- 45 min sessions
Materials (Application Lab): Mixture of baking soda/salt; hot plates or bunsen burners, scales, crucible, crucible tongs, aprons, goggles
Materials (Project): As written by students
Resources: The Case of the Adulterated Baking Soda (CRYSTAL Lab); Burrito worksheet (attached)
Pre-lesson preparation: 20 minutes to set up lab; make baking soda/salt mixture; Have students set up own lab for production of materials

Assessment

Guided/Independent Practice - student corrected
Independent Practice - Homework
Application Lab
Quiz
Task #5 Worksheet (attached)

Student Activity/Tasks

Warm-up: How many Burritos Will We Make?
Guided/Independent Practice in class
Independent Practice as Homework
Application Lab
Quiz
Task #5 Lab Time (Mass Production of Product)

Enrichment/Alternate Activity:

Students may need additional practice problems or labs Students may need additional time to mass produce their product

Cross-Curricular:

Math - ratios and dimensional analysis

Technology Requirements/Tools/Materials

Overhead projector may be used for guided and independent practice

Acknowledgements:

Exploration lab came from: CRISTAL Program, Iowa Chemistry Task Force, University of Northern Iowa, Price Laboratory School, Dr. Jody Stone, Project Director


Additional Resources

Main URL:

Related Lessons


Related Resources

Burrito Worksheet
Chemicals - R - Us Step 5 Worksheet Mass Production



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