Summary
In this lesson, students consider the concept of percent yield as a measure of the efficiency or effectiveness of a chemical reaction. It encourages students to think about how the theoretical yield (the amount of product calculated from stoichiometry) compares to the actual yield (the amount of product obtained in a laboratory experiment) and how percent yield is calculated using these values. Additionally, it prompts students to reflect on the factors that can affect the percent yield, such as side reactions, incomplete reactions, or loss of product during purification processes. It also encourages students to consider how stoichiometry can be applied to real-world scenarios, such as predicting product yields or determining the amount of reactant needed for a desired outcome. Students should also know how to use the gram-to-gram conversion. Consider teaching Balancing Act: Part 2 first.
Essential Question(s)
How can we determine the efficacy of a chemical reaction using percent yield?
Snapshot
Engage
Students will participate in a Silent Ball game to calculate the efficacy of their being able to pass the ball.
Explore
Students select an image to analyze real-world instances in which individuals make predictions, subsequently comparing these predictions to the actual outcomes.
Explain
Students view a video demonstrating the process of calculating percent yield.
Extend
Students complete a card sort by researching and discussing career opportunities available that apply stoichiometry.
Evaluate
Students will demonstrate their understanding of percent yield by completing an Exit Ticket.
Materials
Lesson Slides- Balancing Act Part 3: Stoichiometry_Percent Yield (attached)
One medium-size ball (ie. beachball)
Stoichiometry Percent Yield Notes (Student Copy) (attached; one per student)
Stoichiometry Percent Yield Notes (Teacher Copy)
Career Card Sort handout (attached; one per group)
Card Sort Solutions handout (attached; one per teacher)
Career Reflection handout (attached; cut in half; one half page per student)
Percent Yield Exit Ticket Handout (attached; one per student)
Engage
10 Minute(s)
Use the attached Lesson Slides to follow along with the lesson. Begin with slide 3. Briefly, read aloud the essential question: How can we determine the efficacy of a chemical reaction using percent yield? Then, move to slide 4 and share the objectives with your students to the extent you feel necessary.
Display slide 5 and introduce students to the game Silent Ball. Inform the students that they will pass a ball quietly around the room. Each student who drops the ball, makes a bad pass, or makes a sound is considered out and has to sit down. Let students know they cannot throw to the person next to them but must throw across the room. Before passing, ask students: If you were to pass the ball to each student in the class, theoretically how many times should the ball get to each person without someone having to sit out? (This number is based on how many students are in the class).
Each student has one chance to catch and throw the ball correctly. Remind students who remain in the game to continue standing after they catch and throw. Once all students have completed the round, ask them how many fair catches actually occurred. (This should be the number of students still standing.) Finally, ask students how they might go about calculating how efficient they were in playing Silent Ball? (Students should divide the actual/theoretical and then multiply by 100).
Explore
20 Minute(s)
Go to slide 6 and use the Pick a Pic instructional strategy to invite students to find an image depicting situations in which people may want to measure the efficiency of an event. Instruct students to add their pictures to Padlet and add a hashtag to the picture that describes what it is about (for example, "#BasketballFreethrows"). Provide students with a laptop or tablet to find their picture. Have students scan the QR code or navigate to the link you added to the slide to access the class’s Padlet. Give students 10 minutes to find and add their picture to the Padlet.
Next display slide 7 and ask students to review their classmates’ pictures. Instruct them to select a picture that hasn't been chosen by another student, add their name, and add at least two to three factors that could affect the outcome. For example: The experience of the basketball player, the height of the basketball goal, the number of free throw attempts.
Allow about 15 minutes for students to do so.
Explain
15 Minute(s)
Display slide 8 and pass out the Stoichiometry Percent Yield Notes (Student Copy) handout to each student. Review the vocabulary, percent yield set up, steps for solving percent yield problems with the students on slides 8-11.
Display slide 12 and inform the students they will be completing a problem on their Percent Yield Notes handout while watching the video. Show the Ketzbook’s Percent Yield Made Easy: Stoichiometry Tutorial Part 4 video and have the students work throughout the problem with the video. Ensure that the video is easily accessible and can be viewed without any issues. After watching the video, allocate time for reflection and discussion of misconceptions.
Ask students to think back to the Silent Ball activity and explain how the activity connects to what they just learned about percent yield. Have them identify the theoretical, actual, and percent yield in the scenario.
Extend
15 Minute(s)
The following activity can be used to add a career exploration element to this lesson. Prior to the activity, print the attached Career Card Sort handout so that there are enough for eight groups of students.
Display slide 13 and place students into groups of 3-5 people. Pass out the Career Card Sort handout to each group. Make sure each group has a tablet or laptop to use for research. Tell students the cards have information for five careers related to percent yield. Instruct students to cut out the cards and then sort them into the following categories.
Career Title
Education level required
Years of education needed
Salary range
Tell students that the QR codes or shortened links on each of the career title cards has the information they need to complete the card sort. As each group finishes sorting, use the attached Career Card Sort Solution to check student work. Below is how the card sort should appear after sorting the cards:
Next, pass out the attached Career Reflection handout to each student. Move to slide 14 and ask students to answer the questions on the Career Reflection handout. Students choose the career from the choices that interest them the most and what the day-to-day job description is. They then determine what post-secondary education options are available in their state to attend for that certification/degree (If one is not listed for their state, then the student can list for a neighboring/different state.)
Evaluate
10 Minute(s)
Go to slide 15 and have students complete an Exit Ticket. Give students the Percent Yield Exit Ticket handout, which asks them to solve for the percent yield of the following stoichiometry problem:
Suppose you're in a chemistry lab and you want to synthesize water (H2O) by reacting hydrogen gas (H2) with oxygen gas (O2) according to the following balanced chemical equation:
2H2(g) + O2(g) -> 2H2O(g)
You have 10.0 grams of hydrogen gas (H2) and 40.0 grams of oxygen gas (O2). After carrying out the reaction, you find that you obtain 16.0 grams of water (H2O). Calculate the percent yield of the reaction.
Resources
K20 Center. (2020). Bell ringers and exit tickets. Strategies. https://learn.k20center.ou.edu/strategy/125
K20 Center. (2020). Card sort. Strategies. https://learn.k20center.ou.edu/strategy/147
K20 Center. (2020). Padlet. Tech Tools. https://learn.k20center.ou.edu/tech-tool/1077
K20 Center. (2020). Pick a pic. Strategies. https://learn.k20center.ou.edu/strategy/91
Silent Ball. Playworks. (2019, September 4). https://www.playworks.org/game-library/silent-ball/
YouTube. (2017, March 29). Percent yield made easy: Stoichiometry tutorial part 4. YouTube. https://www.youtube.com/watch?v=_xeqkSQb0Pg