# UTPA STEM/CBI Courses/Limiting Reagent: Theoretical Yield

Course Title: Chemistry
Lecture Topic: Limiting Reagent: Theoretical Yield
Instructor: John Villarreal
Institution:

## Backwards Design

Course Objectives
* Primary Objectives- By the next class period students will be able to:
** Use mole/mass conversion methods and the Periodic Table to calculate the theoretical yield of reaction products.
** Determine the limiting reactant or limiting reagent for a chemical reaction in which amounts of two or more reactants are provided.
** Use a balanced chemical reaction to work stoichiometry problems.
* Sub Objectives- The objectives will require that students be able to:
** Balance chemical reactions or check that reactions are balanced
** Use a Periodic Table to calculate atomic weights of elements and/or molar masses of compounds
** Know how to make unit conversions using dimensional analysis, a step-by-step approach, or a proportion method to do mole/mass conversions
** Use the coefficients of a balanced chemical reaction to do stoichiometry calculations
** Use a scientific calculator to perform the mathematical calculations
* Difficulties- Students may have difficulty:
** In balancing a chemical reaction or checking the reaction coefficients provided to ensure a balanced reaction
** Performing the required mole/mass conversions to determine the number of moles of reactants available from the respective masses
** Determining the limiting reagent or limiting reactant for the reaction being considered
** Using the moles of limiting reagent or limiting reactant to determine the theoretical yield of the product of interest
* Real-World Contexts- There are many ways that students can use this material in the real-world, such as:
** Making a cake out of the various materials and expanding the idea to make multiple cakes
** Determining the number of cars that can be made with specific numbers of car bodies, car engines, and wheels provided
Model of Knowledge
* Concept Map
** Determine whether the reaction provided is balanced or needs to be balanced with proper coefficients
** Determine the number of moles of each reactant for which masses of the reactants are provided
** Determine the mole to coefficient ratio for each reactant for which masses of the reactants are provided
** For the reactant with the smallest mole to coefficient ratio, use the number of moles of the reactant and the coefficients of the balanced reaction to determine the number of moles of the product of interest that can be formed
** Use the molar mass of the product of interest to determine the mass of the product that can form, theoretically
* Content Priorities
** Enduring Understanding
*** Understanding chemical stoichiometry
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** Important to Do and Know
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** Worth Being Familiar with
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Assessment of Learning
* Formative Assessment
** In Class (groups)
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** Homework (individual)
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* Summative Assessment
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## Legacy Cycle

OBJECTIVE
By the next class period, students will be able to:
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The objectives will require that students be able to:
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THE CHALLENGE
A car factory assembles cars from supplies of car bodies, car engines, and car wheels that come in crates furnished by a supplier. Car bodies come in crates that weigh 200,000 kg. Car engines come in crates that weigh 90,000 kg. Crates of wheels weigh 24,000 kg. From this information determine the number of cars (theoretical yield of cars) that can be assembled from one crate of each of these parts.
GENERATE IDEAS
What other information would have to be known to determine the number of cars that could be assembled? What is the mass of a car body? What is the mass of a car engine? What is the mass of a car wheel? What is the "recipe" for the assembly of a car?
MULTIPLE PERSPECTIVES Textbook: Chemistry by Julia Burdge, Chapter 1, Dimensional Analysis and Chapter 3 Stoichiometry; Ratios of Combination Class notes on Dimensional Analysis and on Chemical Stoichiometry
RESEARCH & REVISE
* In-class lectures on unit conversions using dimensional analysis
* Balancing chemical reactions using appropriate coefficients
* Use of a scientific calculator to perform chain calculations or individual calculations
TEST YOUR METTLE
* How many car bodies are available from the information provided?
* How many car engines are available from the information provided?
* How many car wheels are available from the information provided?
* Which part, the bodies, the engines or the wheels will run out first; which will be the limiting part or reactant?
* How many cars can be assembled from the parts available?
* From this practical concept, determine the theoretical yield of ammonia, NH$_3$, in kg that can be made from 50 kg of hydrogen gas, H$_2$, and 800 kg of nitrogen gas, N$_2$, using the reaction, N$_2$ + 3 H$_2$ → 2 NH$_3$.
GO PUBLIC
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## Pre-Lesson Quiz

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## Test Your Mettle Quiz

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