Connected Chemistry Curriculum: Equilibrium

TimeThe CCC Equilibrium unit can be broken into the following lessons:

Phase 1 (42 minutes): Physical and chemical changes with demos, explaining concepts of equilibrium, predicting the submicroscopic view of molecules in equilibrium. CCC student manual pages 1-8.Phase 2 (42 minutes): Discussion of student answers from the previous day, Keq explanation, Simulations of four reactions. CCC student manual pages 9-15.Phase 3 (42 minutes): Completion of student responses and simulations. CCC manual pages 16-18.Phase 4 (42 minutes): Final teacher led discussion of results. Practice worksheet of Keq calculations.Extension Activity (42 minutes): Students investigate everyday example of dynamic equilibrium. CCC manual page 23. Lab experiments and activities would extend the unit further.

LevelHigh School level Chemistry (regular and honors)

PurposeThe purpose of this lesson is to introduce students to the concept of chemical equilibrium. Students will use the University of Illinois at Chicago Connected Chemistry Curriculum, CCC, to understand the chemical representations and chemical symbols of reversible reactions. The CCC Equilibrium unit will be used to model the behavior of molecules in a reversible and irreversible reaction. In addition, students will be able to distinguish reversible and irreversible reactions based on observations of plots of concentration versus time. They will also know that equilibrium position, Keq, of a reversible reaction is defined as the ratio of concentrations of products to reactants.

OverviewThe teacher will begin the unit by reviewing physical and chemical changes. Students will need this background information to understand reversible reactions. The teacher will provide guidance on the predictions of identifying reversible reactions and the meaning of Keq. Students will work with four different simulations. Lastly, the teacher will lead a discussion of the results of identifying irreversible and reversible reactions. If time permits students will research and present a dynamic equilibrium topic (rechargeable batteries, cellular diffusion, role of potassium in body, or pH buffers in the blood).

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Student OutcomesLearner Objectives

I can describe the quantitative relationship between the concentrations of the reactants and products in a system that exists in a state of equilibrium.

I can define Keq and write expressions for Keq for both homogeneous and heterogeneous reactions.

I can relate the magnitude if Keq to relative amounts of product and reactant. I can predict the direction of a reaction, using the reaction quotient, Q, and the

equilibrium constant, Keq. o Q<K the reaction moves to produce more product o Q=K dynamic equilibrium o Q>K the reaction moves to produce more reactant

I can calculate the equilibrium constant when given the equilibrium concentration. I can calculate equilibrium concentrations using the value of the equilibrium

constant, Keq.

Next Generation Science Standards PS1.B Chemical Reactions

Computational Thinking (CT) STEM taxonomy chart:1e. Analyzing Data. See appendix C1f Visualizing Data: See appendix D3a Using Computational Modeling to Understand a Concept: See Appendix E3c Assessing Computational Models: See Appendix F

Teaching Notes

Phase 1 (42 minutes): 1. Activity 1 (CCC manual page 4-5) Teacher will ask students to identify the

differences between physical and chemical changes. Use demonstrations to assess student understanding. Demos could include burning paper, boiling water, combusting vapors, etc.

2. Students should read page 4-5 from the CCC Equilibrium manual and highlight bold face vocabulary words. For the first time students will be introduced to reversible reactions and the meaning of dynamic equilibrium. You may ask students to create a chart comparing irreversible and reversible reactions. Discuss the differences between irreversible and reversible reactions with the class. There are various demonstrations you could use to enhance student understanding of irreversible. Examples of demonstrations include color changing toys or clothing items, N2O4 to NO2 tubes, two-faced thionin demo, cobalt chloride pink to blue, etc.

3. Activity 2 (CCC manual page 6-8). Ask students to make predictions of how submicroscopic molecules will react during a reversible reaction. Students should complete the CCC manual before returning to class the next day.

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Phase 2 (42 minutes):1. Ask students to share answers in class from pages 6-8. Check for understanding of a reversible reaction. If you have a document camera you may wish to present a student’s drawing of their prediction. The teacher will then explain the mathematical calculations of Keq. Page 9 in the CCC manual will provide additional references. If time permits the teacher should ask students to identify the reversible and irreversible reactions found online. The teacher will demonstrate how to open the CCC Equilibrium Simulation 1 program. Go to the website www.connchem.org and download the simulation file.

“Java Program File The Connected Chemistry Curriculum Simulation (ConnectedChemistry.jar) version 1.7.2 (15 December 2012) You only need to download this program to your computer once. It is not necessary to download the program each time you would like to use it.”

2. Once you have downloaded the program open the Equilibrium program by clicking on the “Choose Simulation” link found on the upper left corner. Scroll to Unit 7 Equilibrium Sim 1. Complete the first reaction as a class. The instructions can be found on page 11 of the CCC student manual. Model the way you would like students to complete the remaining three reactions. Allow time for students to complete and draw their observations. Be careful of the time, some students may want to spend too much time perfecting their drawings.

Phase 3 (42 minutes): Students may need the full period to complete the reactions and finish the questions that follow on pages 16-18. If time is short you can skip the questions and move into a class discussion about the results of the simulation. This would also be a good time to use the simulations to verify the Keq values with each reaction.

Phase 4 (42 minutes): Final teacher led discussion of results (if students answers questions in manual). Practice worksheet of Keq calculations.

Pre-class PreparationTeacher should decide on which physical and chemical change demonstrations to use. Labs accompanying this unit will vary. Examples of labs are listed in the “Additional Information” section.

Materials and ToolsCCC student manual pages 1-23 are online at www.connchem.org. This unit is: Unit 7: Equilibrium.

Students will need Java installed on the computers they will be using in order to run the simulations and have access to Molecular workbench. Students will be able to save and print reports.

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AssessmentFormative and Summative assessments can be used to measure student understanding. It is suggested teachers account for completion of student manuals by using stamps or a checklist. Students will write predictions and draw submicroscopic molecules. The accuracy and artistic expression should not be assessed since it is their interpretation of what they observe. Checking for student understanding of learning objectives could be assessed with quizzes and a summative exam.

Additional Information1. Extension Activity (42 minutes): CCC manual page 23. Students investigate everyday example of dynamic equilibrium. Students will spend one period researching the topic and gathering information about how equilibrium applies to the topic. Students would work in groups of four.

2. Online demonstrations of equilibriumThe Chromate – Dichromate Equilibriumhttp://www.digipac.ca/chemical/equilibrium/dichromate/dichromate.htm

3. Lab experiments and activities would extend the unit further. See following attachments for instructions.a. Transfer Tube Activityb. Chemical Equilibrium Finding a Constant Kcc. Chemical Equilibrium and Application of LeChatelier’s Principle

4. Worksheet Examplesa. Intro. to Equilibrium ChemQuest 45 (www.ChemistryInquiry.com)b. Equilibrium and LeChatelier’s Principle (http://www.pogil.org)

AcknowledgementsThese materials are taken from the University of Illinois at Chicago Connected Chemistry Curriculum (CCC), http://www.connchem.org/.

Handouts are at www.connchem.org. The assessment is on the following page.

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