Acid Base Chemistry. Farmington Public Schools Grade Level: 10 Discipline:Chemistry

Transcription

1 Acid Base Chemistry Farmington Public Schools Grade Level: 10 Discipline:Chemistry Author(s) Gary Crisanti Heather Rauf DRAFT: 06/30/06 Farmington Public Schools

2 Table of Contents Unit Summary.3...page(s) Stage One: Standards Stage One identifies the desired results of the unit including the broad understandings, the unit outcome statement and essential questions that focus the unit, and the necessary knowledge and skills. The Understanding by Design Handbook, page(s) Stage Two: Assessment Package Stage Two determines the acceptable evidence that students have acquired the understandings, knowledge and skills identified in Stage One. 7 page(s) Stage Three: Curriculum and Instruction Stage Three helps teachers plan learning experiences and instruction that aligns with Stage One and enables students to be successful in Stage two. Planning and lesson options are given, however teachers are encouraged to customize this stage to their own students, maintaining alignment with Stages One and Two page(s) Appendices page(s) G. Crisanti Heather Rauf DRAFT: 08/03/06 Farmington Public Schools 2

3 Unit Summary This is a unit on Acid-Base Chemistry. It is designed to be a five-week unit used in grade 10, by level 2 chemistry students. It comes after units on Chemical Reactions and Equilibrium which contain knowledge and skills necessary to form an understanding of Acid-Base behavior (ie. reactions, theories of acids-bases, etc.). G. Crisanti Heather Rauf DRAFT: 08/03/06 Farmington Public Schools 3

4 Stage One: Standards Essential Understandings and Content Standards Science #1 Scientific inquiry is an ongoing process building knowledge about events and phenomena. The student will 1.25 frame, hypothesize, design, conduct, analyze, and communicate and defend the results of a controlled scientific experiment discusses the validity of experimental results. #3 The composition and structure of matter determine the properties of matter. The student will 3.14 predict the results of chemical processes based upon atomic theory analyze chemical reactions based upon the principle of conservation of mass and energy. #5 The ever-changing composition and structure of the Earth, its waters, and its atmosphere affect all life forms. The student will 5.21 evaluate how human activities have impacted the atmosphere, land and water. #9 Constancy, patterns, change and evolution permeate all systems. The student will 9.15 demonstrate a system in equilibrium 9.20 formulate predictions based upon identified patterns G. Crisanti Heather Rauf DRAFT: 08/03/06 Farmington Public Schools 4

5 Unit Outcome Statement As a result of this unit the students will know and understand how the theories of acids and bases explain and quantify the properties of these substances and how they affect our daily life. Students will understand uses and behaviors of acids and bases such as: Household uses Effect on infrastructure (Roads, Buildings, Monuments, etc.) Environmental impact Predict results of acid-base reactions and perform titrations Essential Questions What is an acid? What is a base? How do we know the difference? How is human activity affecting the balance of acids and bases in the environment? How do acids and bases influence peoples lives? Knowledge and Skills Knowledge Define the Arrhenius and the Bronsted-Lowry theories of acids and bases Know some of the chemical and physical properties of acids and bases Demonstrate knowledge of the equilibria constants K w,k a, and K b. Define and describe ph and poh Explain the process of titration Describe the products of neutralization reactions Define a buffers Identify acid precipitation and its cause Describe the relationship between acids, bases and biological systems Skills/Processes Classify acids and bases based on chemical structure. Discover if a substance contains an acid or a base depending upon its properties. Using the values of K a, and K b to make strength predictions. Write formulas for and name acids and bases. Investigate the acid-base nature of water, K w Determine acid-base conjugate pairs. Compare reactions of acids and bases to previous knowledge. G. Crisanti Heather Rauf DRAFT: 08/03/06 Farmington Public Schools 5

6 Calculate ph and poh and relate the two values Perform an acid-base titration Measure ph using various methods Thinking Skills Infer from/evaluate ideas-draw conclusions: Laboratory situations, Performance Assessment, and Acid Rain Study Identify appropriate evidence: Is their evidence of Acid Precipitation: Acid Rain Study Distinguish between cause and effect: What effect does acid rain have on the local infrastructure and environment Interdisciplinary Skills Language Arts Students will display appropriate use of Labs which are accurate, clear and scientifically valid. Mathematics Students will make use of Mathematical Skills to perform calculations. G. Crisanti Heather Rauf DRAFT: 08/03/06 Farmington Public Schools 6

7 Stage Two: Assessment Package Authentic Performance Task Goal: Determine if the effluent produced by a manufacturing facility will pass the EPA Guidelines for ph and to determine what is required to adjust the ph of the effluent. Role and Audience: Take on the role of a Chemist working for a manufacturing facility. As a chemist it will be the students job to determine if a sample of effluent from the facility meets the EPA Guidelines for ph. The chemists are also required to determine the concentration of acid in the effluent and decide the quantity of neutralizer necessary to bring the ph of a one-liter sample to the correct range. Standards and Criteria for success: Students will report their results to their supervisor in the form of a laboratory report. Students will: frame, hypothesize, design, conduct, analyze, and communicate and defend the results of a controlled scientific experiment; predict the results of chemical processes based upon atomic theory; analyze chemical reactions based upon the principle of conservation of mass and energy; interpret trends and evaluate patterns of change using tables, graphs, and equations; discuss the validity of experimental results; Represent, describe, and analyze mathematical relationships and patterns using simple equations and graphs. (1.25, 1.27, 3.14, 3.15, and 9.20) Tests, Quizzes, and Other Quick and Ongoing Checks for Understanding Practice questions and problems: To assess students knowledge and ability to represent, describe, and analyze mathematical relationships and patterns using simple equations; demonstrate a system in equilibrium; formulate predictions based upon identified patterns on a more topical basis (3.14, 3.15, 9.15, and 9.20) Unit Test: To assess students knowledge and ability to represent, describe, and analyze mathematical relationships and patterns using simple equations; demonstrate a system in equilibrium; formulate predictions based upon identified patterns (3.14, 3.15, 9.15, and 9.20) Quizzes: Same as Practice questions and problems.(3.14, 3.15, 9.15, and 9.20) Entrance/Exit Questions: Same as Practice questions and problems.(3.14, 3.15, 9.15, and 9.20) Student Self Assessments: Same as Practice questions and problems.(3.14, 3.15, 9.15, and 9.20) Projects, Reports, Etc. Observations of students as they work in Laboratory situations in order to assess laboratory skills and understanding of important related concepts. Lab design: frame, hypothesize, design, conduct, analyze, and communicate and defend the results of a controlled scientific experiment. (1.25 and 1.27) G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 7

8 CSDE Embedded Task; Strand III: Global Interdependence. Performance Task; Determine the effect of simulated acid rain upon various building materials. STS; Connecticut Brownfield Sites: Explore environmental issues that are close to home. Formulate a general procedure for exploring the effects of suspected contaminants on land that was once used for industrial, commercial or manufacturing purposes and surrounding property Acid Precipitation Study: To assess students recognition that science is a community activity in which results are shared and evaluated amongst peers and evaluate human activities on the environment (5.21) Formal lab reports: To determine if students are able to write an informative piece that is clear, accurate, draw valid conclusions, discuss the validity of results, and represents information from a variety of different sources. (1.25 and 1.27) G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 8

9 Stage Three: Learning Experiences and Instruction Learning Experiences and Instruction Guiding Questions Instructional Strategies Checking for Understanding Why do we study acids and bases(days 1) Are you familiar with the terms acid?; base? Have you ever used something that contained an acid or a base? Do acids and bases exist naturally in the environment or are they man made? Presentation of Essential Questions Class discussion of guiding questions. Determine what they already know and to establish the importance of acids and bases in their daily lives. Exit Question: Why do you think we should study acids and bases? Do human activities human affect the balance of acids and bases in the environment? Record the results of this discussion and place them some where in the room where they will remain visible for the entire unit. Be sure to lead them to the topic of Acid Precipitation. One class period. Properties of Acids and Bases (Days 2 3) What properties do you think acids and bases might have? What evidence do you have of these properties? Are some of these properties real or contrived? Laboratory Activity Properties of Acids and Bases. Take student results and draw conclusions about the properties of each. Have students relate the properties discussed in this lesson to there everyday experiences and possible effects on the environment and infrastructure. Results of student investigation Quiz Quiz on the properties of Acids and Bases. Affect of Acid Precipitation (Days 2) What are the implications of Student research project acid precipitation? Have students summarize their results and the results of each group. Summary of results G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 9

10 The Arrhenius Theory of acids and bases (Days 1) How do chemists define what an acid or a base is? Do all acids have something in common? Do all bases? Show ionization process and dissociation process of acids and bases. Have students examine the products of such reactions and search for a commonality amongst acids and bases. Exit Question: Write the equation showing the ionization and dissociation processes and have students identify the common links Worksheet on Arrhenius acids and bases Link the commonality of acids and the commonality of bases with their properties. Formula writing for acids and bases (Days 1) How do chemists and other Class discussion of formula scientist represent acids and writing bases using chemical symbols? Practice questions for formula writing Quiz on Formula Writing for Acids and Bases Calculating and measuring ph and poh (Days 3) Have you encountered the Class discussion of ph, poh. term ph before? Have you ever measured the ph of something in your home, community, or school? Before showing how to use the equation go over base 10 logarithms with the students. Calculating ph: Homework. Student activity results Quiz on calculating ph Have the students perform the If so what did you use to activity Acids and Bases, are measure ph? they important to me?. Acid Rain study(days 21) conducted over the length of the unit Results of study Does the Town of Farmington experience acid precipitation? Is there any evidence of the affect of acid precipitation in the Town of Farmington? Students perform Acid Rain study. Prompt: Answer the EQ: How is human activity affecting the balance of acids and bases in the environment? CSDE Embedded Task; Strand III: Global Interdependence (Days4) Performance Task; Determine Student reports the effect of simulated acid rain upon various building materials. STS; Connecticut Brownfield Sites: Explore environmental issues that are close to home. Formulate a general procedure for exploring the effects of suspected contaminants on land that was once used for industrial, commercial or manufacturing G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 10

11 purposes and surrounding property. Web sites listed in the Appendix. The Bronsted Lowry Theory of acids and bases (Days 1) The hydrogen ion has never Present the Bronsted-Lowry been found in a sample of theory of acids and bases on water. So how do we explain the board. Have students the properties of acids and practice identifying proton bases if this is true? donor and proton acceptor. Compare this theory with the Arrhenius theory. Introduce the idea of reversible reactions for acids or bases in solution Relative strength of acids and bases (Days 3) Why is it that acids of the same concentration can have different strengths? Why is it that bases of the same concentration can have different strengths? Is there a difference between strength and concentration? K a and K b (Days 1) How do reactions of acids and bases compare to those seen in previous units? Can we establish mathematical relationships similar to those established in the unit on equilibria? Laboratory activity on comparing ph of strong and weak acids and bases. Summarize results of activity then ask the guiding question. Revisit complete ionization and incomplete ionizations (reactions that go to completion vs. those in equilibrium) and there relationship to strength. Have students compare reactions. Present relative strengths of conjugate acidbase pairs. Class discussion of Ka and Kb. Spend time showing how to set up Ka and Kb expressions and how to calculate Ka and Kb. Establish the relationship between the value of Ka or Kb and strength. The Hydrolysis of water and ph (Days 1) What effect does adding an acid or a base have on pure water? Class discussion of water hydrolysis. Have students look at the stoichiometric relationship between the hydrogen ion and the hydroxide ion. Student practice questions Exit Questions: Have students write equations and identify conjugate acid-base Prompt: Answer the EQ: What is an acid? What is a base and how do the differ? Summary of results Homework on Ka and Kb Quiz Student practice problems Engage them into explaining how this relationship answers the question as to why water is neutral. Introduce the Kw constant and expression. G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 11

12 Discuss how adding an acid or base to pure water changes the hydrogen ion concentration and therefore changes the ph of the water. Acid-Base Reactions (Days 1) If not have you ever seen T.V. commercials for medicines for heartburn? What is the condition called heartburn? What is an antacid? What does the name imply? Acid-Base Titration (Days 3) How does a company that produces an antacid know how much you might need to take? Introduce neutralization reactions. This concept is initially introduced in the lesson on properties of acids and bases. Show how the reaction between a Bronsted-Lowry acids and bases and that the products are water and a salt. Titration. Go back and review acid-base neutralization reactions then introduce the idea of equivalence, and equivalence point. Introduce the use of an indicator to determine the equivalence point and end point of the indicator. Exit Questions: Write an equation showing the reaction between an acid and a base to form a salt and water. Have students identify the salt Have students practice solving titration problems. Student laboratory reports Student laboratory designs Student self assessment Buffers (Days 2) Have you ever heard of the term ph balanced? Is there any way of preventing negative affects of acids and bases? Have students perform the acid-base titration lab between a strong acid and a strong base and the titration between a weak acid and a strong base. Have students design a lab to measure the effectiveness of various antacids on simulated stomach acid using the technique of titration. Class discussion of buffers. Have students perform the laboratory activity on preparing a buffer and testing its use. Reporting of results from lab Essential Question (Days 1) Discuss the results of this activity in order to assess students understanding. G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 12

13 Prompt: Answer the EQ: How do acids and bases influence peoples lives? Formal Assessments (Days 4) Performance Assessment Unit Test G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 13

14 Appendices: All copies are in the Chemistry Units Binder in the Science Office. 1) Unit Test 2) Performance Assessment 3) Quizzes 4) Practice questions and problems 5) Laboratory Activities Complete set of Essential understandings for your discipline Any student work sheets List of resources including texts, videos, field trips, web sites, etc. Text: Chemistry; Addison Wesley; Prentice Hall Publishing Lab Manual: Chemistry; Addison - Wesley CD - rom: Chem ASAP!; Addison Wesley Resources: Farmington High School Library Web sites for CAPT STS G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 14

15 ACID - BASE PERFORMANCE ASSESMENT INTRODUCTION: Manufacturing facilities often are built on a large river or lake. One of the reasons for placing these facilities on a waterway was to have an easily accessible means of disposing of industrial waste. In the past the waste was just dumped into the water without being treated. The continued dumping of these wastes, which increased over time due to increases in manufacturing, began to take their toll on the environment. During the 1970 s legislators passed several laws regulating the waste that manufacturing facilities could dump into these waterways. The government agency responsible for making sure that companies obey the law is the Environmental Protection Agency or EPA. One thing that a company must be in compliance with is the ph level of the effluent (waste which is usually mostly water and that has unwanted industrial products dissolved in it) that is released into the waterway. Therefore the facility must have chemists that continuously monitor the ph of the effluent that is dumped into the waterway and make adjustments by adding the appropriate material that will either raise or lower the ph of the effluent so that the ph is within an appropriate range. TASK: It is your job to take on the roll of the chemist. You will be given a sample of simulated effluent from a manufacturing facility. The effluent contains hydrochloric acid. It will be your job to make the determination as whether the effluent will pass the EPA guidelines for ph. If it does not then you will have to make the decision as to what you would need to add to the effluent in order to adjust the ph. The substance we use to make the adjustment in ph is sodium carbonate (Na 2 CO 3 ). Then you will have to add the appropriate material in the correct amount and retest your sample to make sure that you have completed your task. EPA Guidelines Allowable ph range: 6.5 to 8.5 Material to be used to adjust the ph Sodium carbonate Na 2 CO 3 In order to solve this problem you will be allowed to use any equipment or materials that we used during the acid base unit. The reaction of hydrochloric acid with sodium carbonate is given below 2 HCl (aq) + Na 2 CO 3 (s) 2 NaCl (aq) + H 2 O (l) + CO 2 (g) Remember the numbers in front of the compounds (coefficients) represent the mole ratio of reactants and products. Your boss will need you to provide her with the following information The ph of the effluent. The concentration in moles/l or M of hydrochloric acid in the effluent. The amount of sodium carbonate you will need to add to your test sample in order to change its ph to the proper level. The ph of your sample after you have adjusted the ph. The amount of sodium carbonate required to adjust the ph to so it will meet the EPA guidelines. You must give the amount as the number of grams of sodium carbonate needed per liter of effluent G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 15

16 You may not do the sixth bullet by trial and error. This will earn you an automatic F! The following Grading Guidelines will be followed. A Your report is well organized, includes all appropriate data, and answers all of the above bullets correctly. B Your report is well organized, includes all appropriate data, and answers most of the bullets above correctly. C Your report is well organized, includes all appropriate data, and answers a few of the bullets above correctly D Your report is poorly organized, or does not include all appropriate data, and answers few of the bullets above correctly F Your report is poorly organized, does not include all appropriate data, and answers none of the bullets above correctly G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 16

17 TEST ON ACIDS AND BASES NAME: DATE: MULTIPLE CHOICE: Pick the one that best answers the question. 1. Acids taste a. Sweet b. Sour c. Bitter d. Salty 2. Bases react with a. acids b. metals c. nonmetals d. both a and b 3. Acids react with a. bases b. metals c. nonmetals d. both a and b 4. Bases taste a. Sweet b. Sour c. Bitter d. Salty 5. An acid is defined as a. A proton donor b. A proton c. A hydroxide ion d. A proton acceptor 6. A base is defined as a. a proton donor b. a proton c. a hydroxide ion d. a proton acceptor 7. Acids produce when dissolved in water a. Na+ ions b. OH- ions c. H+ ions d. Cl- ions 8. Bases produce when dissolved in water a. Na+ ions b. OH- ions c. H+ ions d. Cl- ions G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 17

18 9. A solution with a ph of 7 is.. a. Neutral b. Acidic c. Basic d. Salty 10. A solution with a ph of 11 is a. Neutral b. Acidic c. Basic d. Salty 11. The salt produced from a strong acid and a weak base is a. Acidic b. Basic c. Neutral d. Sweet tasting 12. The salt produced from a strong base and a weak acid is a. acidic b. basic c. neutral d. sweet tasting 13. If I add an acid to water the concentration of OH- a. Increases b. decreases c. stays the same d. water does not contain OH- 14. If I add a base to water the concentration of OH- a. Increases b. Decreases c. Stays the same d. Water does not contain OH- 15. An acid base indicator is a dye that a. is always the same color b. is colorless c. is the same color in both acids and bases d. is one color in an acid and a different color in a base 16. Two opposing events happening at the same time and the same rate is called. a. Activation energy b. Activated complex c. Enthalpy d. Equilibrium 17. The Keq expression for the following reaction is HF (aq) + H 2 O (l) H 3 O + (aq) + F - (aq) a. [H 3 O + ] [F - ] / [HF] b. [HF] / [H 3 O + ] [F - ] c. [H 3 O + ] [F - ] / [HF] [H 2 O] G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 18

19 Problems refer to The following reaction is in equilibrium: 2 H 2 + O 2 2 H 2 O 18.. What happens if I add H 2? a. shift to the left b. shift to the right c. nothing d. the rate of both reactions increases 19. If I remove O 2 from the reaction above what happens? a. shift to the left b. shift to the right c. nothing d. the rate of both reactions increases 20. If the forward reaction is exothermic heating the reaction will cause it a. shift to the left b. shift to the right c. nothing d. the rate of both reactions increases 21. If a solution has a ph of 13 it is a. acidic and weak b. basic and strong c. basic and weak d. acidic and strong 22. For pure water the following is true. a. the H+ conc. = OH- conc. b. the H+ conc.> OH- conc. c. the H+ conc.< OH- conc. d. the OH- conc. is zero 23. In the reaction HCl + H 2 O H 3 O + + Cl - the water is acting as a(n) a. base b. salt c. acid base indicator d. acid 24. What is the equivalence point in an acid - base titration? a. the H+ conc. = OH- conc. b. the H+ conc.> OH- conc. c. the H+ conc.< OH- conc. d. the OH- conc. is zero 25. What is the ph of the solution that is produced after the titration of a strong acid and a strong base is? a. 7 b. 6 c. 9 d. 4 G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 19

20 FREE RESPONSE 1. For each of the following write the products formed when you dissolve the substance in water. Acid: HCl + H 2 O Base: F 1- + H 2 O Acid: HClO 4 + H 2 O Base: Br 1- + H 2 O 2. Complete the following chart. Show the work below H+ conc. OH- conc. ph Acidic or basic 5.7 x 10-5 M x 10-3 M x M 1 x 10-4 M G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 20

21 3. Label the acid, base, conjugate acid, and conjugate base. HF + H 2 O F - + H 3 O + 4. What is meant when we say that a solution is neutral? G. Crisanti Heather Rauf DRAFT: 6/30/06 Farmington Public Schools 21