Lesson Plan Format - California State University, Northridge
(A) Major Concepts
• General properties of acids and bases
• Acids are proton donors
• Bases are proton acceptors
• Strength of acids and bases
• Salt formation
• Indicators and pH scale
• What is acid rain?
(B) Performance Objective / Content Standards
When the lesson is complete, students will be able to…..
• Classify acids and bases according to their properties. => knowledge, comprehension, analysis, evaluation, inductive reasoning => 5e. Students know how to determine whether a solution is acidic, basic, or neutral.
• Recognize acids as proton donors and bases as proton acceptors. => knowledge, comprehension, analysis, deductive reasoning => 5e. Students know how to determine whether a solution is acidic, basic, or neutral.
• Interpret warning and safety labels on products containing acids and bases. => knowledge, comprehension, application, evaluation, critical thinking
• Compare and contrast the strength of an acid or base with its concentration. => knowledge, comprehension, application, analysis, evaluation, inductive reasoning.
• Describe the process of neutralization. => knowledge, comprehension, synthesis, deductive reasoning => 5a. Students know reactant atoms and molecules interact to form products with different chemical properties. 5c. Students know chemical reactions usually liberate heat or absorb heat. 5e. Students know how to determine whether a solution is acidic, basic, or neutral.
• Explain how antacids work to reduce acidity. => knowledge, comprehension, application, synthesis, evaluation, deductive reasoning => 9a. Plan and conduct a scientific investigation to test a hypothesis.
• Describe how indicators can be used to classify solutions as acidic or basic. => knowledge, comprehension, application, synthesis, evaluation, creative thinking
• Compare and contrast normal rain and acid rain. => knowledge, comprehension, application, analysis, inductive reasoning
• Compare the natural and industrial sources of acid rain. => knowledge, comprehension, application, analysis, synthesis, evaluation, inductive reasoning
• List the effects of acid rain. => knowledge, application, evaluation
(C) Materials and Equipment
• Activity 22.1 Properties of acids and bases in aqueous solution:
7 small test tubes, 2 corks to fit the test tubes, red and blue litmus paper, baking soda, magnesium turnings, vinegar, lemon juice, carbonated water, washing soda, soap solution, unknown solution (diluted ammonia water), 10mL graduated cylinder, safety goggles, lab apron
• Demonstration 1: Disappearing ink available in many toyshops.
• Demonstration 2: raw eggs of the same size, acetic acid solution, hydrochloric acid solution. Timer.
• Demonstration 3: a head of red cabbage, heating mantle, vinegar, baking soda, ammonia water, 0.1 M HCl solution
• Activity 22.2 Neutralization and pH change
1.0 M HCl, NaOH solutions, BTB solution, 5 Styrofoam containers, pH paper, 20mL graduated cylinder, thermometer, 2 250mL beakers
(D) Outline of Lesson (provide a general time frame)
|Period |Activity |Content |Time (min.) |
|1 |Warm-up |Vocabulary |5 |
| |Introduction |Introduction of the chapter 22 |5 |
| |Lab Experiment |Common properties of acids & bases |30 |
| |Discussion |Discussion of the results from the lab. |17 |
|2 |Warm-up |Tastes of Foods |5 |
| |Demonstration |Disappearing ink |10 |
| |Lecture |Definitions of acids and bases |30 |
| |Group work |The strength of acids and bases |10 |
| |Summary |Assigning homework 1 |2 |
|3 |Discussion |The strength of acids and bases Safety and reading labels |30 |
| |Demonstration |Removing the shell from a raw egg without breaking the egg. |5 |
| |Introduction |Section 22.2 Neutralization and pH |5 |
| |Lecture |Neutralization Reaction Salt formation, Antacid |15 |
| |Summary |Finding the Result of demonstration Assigning homework 2 |2 |
|4 |Warm-up |Vocabulary |5 |
| |Demonstration |Cabbage juice indicator |10 |
| |Discussion |Indicators and pH scale |30 |
| |Lecture |Acid rain |10 |
| |Summary |Assigning homework 3 |2 |
|5 |Lab experiment |Activity 22.2 Neutralization reaction |30 |
| |Discussion |Neutralization and pH change |17 |
| |Summary |Chapter review |10 |
(E) Lesson activity
1) Warm-up/Dispatch Activity
1. Section 22.1: Vocabulary – find the meaning of the vocabulary listed in the board with your textbook glossary. (5 min.)
|Acid |
|Acid anhydride |
|Base |
|Basic anhydride |
|Electrolyte |
|Organic acid |
2. Taste of Foods: write down the names of foods you ate this morning and their tastes.
3. Section 22.2: Vocabulary – find the meaning of the vocabulary listed in the board with your textbook glossary. (5 min.)
|Alkalosis |
|Indicators |
|Neutralization reaction |
|Neutral solution |
|PH scale |
|Salts |
|Antacid |
2) Introduction. How does today's lesson relate to past lessons?
1. Introduction of Chapter 22. and Section 22.1.1 (10 min.)
➢ Read and answer the question: Why do some hydrangeas have pink flowers, while others have blue flowers? (Text book pp.540~541)
➢ This chapter is a part of Unit 7 ‘chemical system’ which consists of chapter 21. Chemical reactions, chapter 22. Acids, bases and salts, and chapter 23. The environmental and chemical technology. In this unit, students learn about what happens and how it affects our life when chemical reactions take place. Especially, Chapter 22. Acids, Bases and Salts is introduced as a representative chemical reaction which is closely related to our life. From this chapter, students will learn how to classify substances based on their properties and what indicates a chemical reaction (neutralization) occurring. These are review of former Unit. 5 Matter and former Chapter. 21.
➢ Look at the concept map of the chapter.
➢ Introducing Learning objectives
2. Section 22.1.2: Demonstration –Disappearing ink
➢ Disappearing ink contains the indicator thymolphthalein. When squirted onto a cloth, the blue color is visible. This will dissipate as the CO2 gas from the atmosphere dissolves into the solution and neutralize the slightly basic solution. I will challenge students to explain this phenomenon. This demonstration shows that CO2 gas is an acid anhydride of carbonic acid.
3. Section 22.2: Neutralization and pH
➢ Acids and bases are substances. And substances undergo chemical reactions. When an acid reacts with a base, both of them lose their properties and become new substances. How do we know a chemical reaction take place, especially neutralization reaction?
➢ Watch a demonstration with red cabbage juice and answer the question: What causes the color change of red cabbage juice?
4. Section 22.3: Acid Rain
➢ The concept of acid rain is related to the concept of pH and acid anhydride. Most pollutants of acid rain are nonmetallic oxides, which are acid anhydride.
3) Lecture/discussion (Lecture notes)
Section 22.1 Recognizing Acids and Bases
1. Common properties of acids and bases dissolved in water (Textbook p.542~544)
◆ Classify acids and bases according to their properties.
1. Emphasize that as elements are grouped in the periodic table in terms of their atomic structures and properties, chemical compounds can be grouped according to their properties.
2. During the lab activity, students will fill out handout 1.
3. After lab activity 22.1(it takes 30 min.), discuss the general properties of acids and bases as an activity of drawing conclusions.
4. During the activity, the hydrogen gas will be identified by combustion as a teacher demonstration. This confirms that every acid has hydrogen atom in its molecule. I will use this fact when the definition of acids is taught.
5. During this activity, students will develop inductive reasoning skills finding common properties of acids and bases.
6. The properties will be summarized a table as a graphic organizer with two columns (diagram 1) to make it easy to compare and contrast the properties of acids and bases.
7. I will challenge students to compare the results of their knowns and the unknown I provide. I use diluted ammonia solution as an unknown solution. This fact will be used when I teach the definition of bases.
8. I give them a chemical equation that explains the reaction of acids with carbonates and metals.
Reactions of acids with
Metals: Zn + 2HCl → ZnCl2 + H2
Carbonates: 2HCl + CaCO3 → CaCl2 + H2O + CO2
9. Remind the reactivity of metals from chapter 21 to explain the reactivity of acids with active metals.
22.1.2 Acids are Proton Donors (Textbook p.545~546)
◆ Recognize acids as proton donors and bases as proton acceptors.
1. All acids produce hydrogen gas when they react with active metals such as Mg and Zn. This means acids has hydrogen atom in their molecules.
2. All acids are electrolytes that generate hydrogen ions.
3. Arrhenius’ definition is first introduces with diagram 2 and later Bronsted-Lowry definition is taught.
Arrhenius’ definition of acids: Acids in water produce hydrogen ions (H+). HA → H+ + A-
Bronsted-Lowry definition of acids: Acids are proton donors. HA + H2O → H3O+ + A-
[pic]
4. As demonstrated in the introduction activity, acid anhydrides are introduced as acidic substances. This will be connected to the pollutants of the acid rain.
Acid anhydrides: nonmetal acids readily form acids upon the addition of water.
SO3 + H2O → H2SO4, CO2 + H2O → H2CO3
5. To help students understand the definition of acids, I will have them practice the ionization process of acids with a handout 2.
6. When an acid is added to water, it reacts, which is a chemical change called ionization. Acids are compounds that are capable of donating a proton (hydrogen ion) to a water molecule to form a hydronium ion (H3O+).
7. Organic acids have at least a group of COOH instead of H. Many foods which taste sour includes organic acids. For example, vinegar has acetic acid, CH3COOH, yogurt has lactic acid, C2H5OCOOH.
3. Bases are Proton Acceptors (Textbook p.546~547)
◆ Recognize acids as proton donors and bases as proton acceptors.
1. All bases are electrolytes that generate hydroxide ions.
2. Arrhenius’ definition is first introduces and later Bronsted-Lowry definition is taught.
Arrhenius’ definition of bases: Bases in water produce hydroxide ions (OH-). BOH → B+ + OH-
Bronsted-Lowry definition of bases: Bases are proton acceptors. B + H2O → BH+ + OH-
[pic]
3. Ammonia gas doesn’t have hydroxide ion in its molecule, but when it dissolved into water, it accepts a proton from water molecule and becomes basic.
4. Basic anhydrides are metal oxides which readily form bases upon the addition of water.
MgO + H2O → Mg(OH)2, CaO + H2O → Ca(OH)2
5. To help students understand the definition of bases, I will have them practice the ionization process of bases with a handout 2.
22.1.4 Strength of Acids and bases (Textbook p.548~549)
◆ Compare and contrast the strength of an acid or base with its concentration.
◆ Interpret warning and safety labels on products containing acids and bases.
1. This section will begin with group work with handout 3. In this activity, students will think about what is acidity and what acidity depend on.
Acidity: Degree of being acidic. It depends on the concentration of hydrogen ions in a solution.
2. I will emphasize the difference between strong acid and more acidic. Strong acids are acids (bases) that have a higher degree of ionization. Thus, even small amount of molecules can produce large number of hydrogen ions (hydroxide ions) resulting in strong acidity (basicity). Even weak acid can produce large number of hydrogen ions when a large amount of molecules are dissolved into water leading to be more acidic.
Strength of an acid: indication of the extent that the acid molecules break apart to release hydrogen ions. (=Degree of ionization)
Strong acids: almost all the molecules break apart to release hydrogen ions. Ex) HCl, H2SO4, HNO3…
Weak acid: Only part of the molecules break apart to produce fewer hydrogen ions than a strong acid of the same concentration. Ex) CH3COOH, H2CO3, H3PO4….
Strength of a base: indication of the extent that the base molecules break apart to release hydroxide ions. (=Degree of ionization)
Strong bases: almost all the molecules break apart to release hydroxide ions. Ex) NaOH, KOH, Ca(OH)2…
Weak acid: Only part of the molecules break apart to produce fewer hydroxide ions than a strong base of the same concentration. Ex) Mg(OH)2, NH3, Al(OH)3…..
3. Students often equate acids with corrosion, but most of foods we eat are acidic. While some acids are corrosive – i.e., battery acid (sulfuric acid) and muriatic acid (hydrochloric acid) – others are weak acids and a regular part of our diet, including vinegar (which is about 5% acetic acid), orange juice (citric acid), and vitamin C (ascorbic acid).
4. Many cleaning agents used, including ammonia (an aqueous solution of ammonia gas) and lye (sodium hydroxide), are bases. These can be dangerous because sodium hydroxide can cause serious chemical burns.
5. Strong acids and most concentrated weak acids are dangerous, causing severe burns for even minor contact. Generally, acid burns are treated by rinsing the affected area abundantly with running water (15 minutes) and followed up with immediate medical attention. In the case of highly concentrated acids, the acid should first be wiped off as much as possible, otherwise the reaction of the acid dissolving in the water could cause severe thermal burns. In addition to dangers from the acidity, even dilute solutions of weak acids may also be dangerous, due to toxic or other effects of the ions involved.
NFPA Code for NaOH: H 3; F 0; R 1
F0- not combustible. Contact with moisture or water may generate sufficient heat to ignite combustible substances.
H3 - highly dangerous to health
R1 - reactive
MSDS:
[pic]
NFPA Code for HCl: H 3; F 0; R 2
F0- not combustible. Contact with moisture or water may generate sufficient heat to ignite combustible substances.
H3 - highly dangerous to health
R1- very reactive
MSDS :
[pic]
6. Demonstration that shows the difference between strong acid and weak acid will be held. Acetic acid and hydrochloric acid of the same concentration are used to remove the shell of raw eggs. Compare the time that takes to remove the shell of raw egg.
Section 22.2 Neutralization and pH
22.2.1. Salt formation and antacid (Textbook p.550~552)
1. An acid reacts with a base to form water and a salt. This is a special type of double replacement reaction called neutralization reaction. Water is not an acid or base. It is neutral. When an acid and a base form water, they lose their acidic and basic properties.
Neutralization Reaction: double replacement reaction
HA + BOH → H2O + BA
Acid base water salt
2. Salts are ionic compounds that can be produced by the neutralization reaction of an acid by a base. A large number of salt exist, but each contains a positive ion (other than H+) and a negative ion (other than OH-).
3. to understand of the process of neutralization, students will practice with handout 4.
4. Antacids consist of weak bases, such as carbonates, bicarbonates, or hydroxides. People have haertburn when their stomach make too much hydrochloric aicd. To reduce the acidity of stomach juice, antacids are used to cause neutralization of HCl. Like all drugs, antacids also have some sideeffect. If antacids are abused, alkalosis results from higher than normal amounts of base in the blood.
22.2.2. pH scale and indicators (Textbook p.552~556)
1. This section will begin with a demonstration. In a demonstration, red cabbage juice will be introduced as an indicator. Students will be challenge to explain what causes colors to change. Also, I will use two kinds of acids of the same concentration and ask students how we can determine the acidity of each solution.
2. With diagram 3, I explain the concept of indicator.
Indicators are organic compounds whose color is dependent on the H+ concentration of a solution. They change color as a result of gaining or losing H+ ions.
3. If we compare the acidity of two solutions from the demonstration, we need to know how much the concentration of hydrogen ions in each solution. The pH scale provides information about the concentration of H+ in a solution. The pH scale was designed for use with dilute solutions. It is a range of numbers from 0~14. (Diagram 4)
pH < 7: acidic pH = 7: neutral pH > 7: basic
The less a pH of a solution, the more acidic it is. Each step in the pH scale corresponds to a tenfold change in concentration of the H+ ion.
Section 22.3 Acid Rain
22.3.1. Acid rain (Textbook p.557~559)
1. The pH of normal rain or snow is about 5.6. This slight acidity of normal rain is a result of dissolved carbon dioxide which produces a dilute solution of carbonic acid. I will have students recall the concept of acid anhydride learned in section 22.1.
CO2 + H2O → H2CO3 → H+ + HCO3-
2. Acid rain is defined as rainfall that is more acidic than pH 5.6.
3. Acid rain is caused by sulfur oxides and nitrogen oxides. Primarily SO2, SO3, NO and NO2. They are released by natural and man-made sources.
SO2 + H2O → H2SO3 SO3 + H2O → H2SO4
4. Major sources of sulfur and nitrogen oxides are power generation plants, petroleum refineries, industrial furnaces and automobiles. Coal with high sulfur content is a serious pollutant.
5. Acid rain damages a ecosystem and stone buildings. A relationship between high acidity in lakes and reduced fish populations has been established. Acid rain has also been linked to decreased soil fertility and reduced crop and forest yields.
6. Acid rain also causes the decomposition of stone buildings and statues. As learned, acid can react with carbonates to produce CO2 gas. H2SO4 + CaCO3 → CaSO4 + H2O + CO2
22.3.2. Neutralization reaction and pH change
1. In activity 22.2 with handout 5, students will learn a characteristic of chemical reaction. Neutralization reaction is exothermic, which means this reaction produce heat.
2. The pH change will be monitored using pH paper and an indicator.
3. After the activity, discussion will take place about the neutralization and pH change.
Number of H+ > Number of OH- : acidic , pH 7
Number of H+ = Number of OH- : neutral , pH =7
4. With handout 6, student will understand the process of neutralization reaction.
• Diagrams 1
|22.1.1 Common properties of acids and bases dissolved in water |
|Acids |Bases |
|Taste (sour) (when diluted enough to be safely tasted) |Taste (bitter) (when dilute enough to be safely tasted) |
|Conduct electricity => (electrolytes) |Conduct (electricity) => (electrolytes) |
|Turn blue litmus red |Turn red litmus blue |
|React with active metals to produce (hydrogen gas) |Do not react with most metals to produce hydrogen gas |
|React with carbonates to produce (carbon dioxide gas) |(exceptions are Al, Zn, and Cr) |
|React with bases to form salts |Feel (slippery) |
| |React with acids to form salts |
• Diagram 2 : Arrhenius’ definition of acids and bases
[pic]
• Diagram 3: Colors of indicators in various solutions.
[pic]
• Diagram 4: the pH scale
[pic]
Handout 1 (Textbook p.544)
Activity 22.1 Properties of acids and bases in aqueous solution (30min.)
Purpose: To observe and describe the properties of some common acids and bases and to use these observations to classify an unknown solution.
Procedure
1. Put on your safety goggles and lab apron.
2. With a grease pencil, number seven test tubes from 1 to 7.
3. Place a pea size amount of washing soda into test tube number 4. Similarly, place a pea size amount of baking soda in test tube number 5. Add water so the test tubes are about half full. Cork the test tubes and shake to dissolve the solids.
4. Half fill the remaining test tubes with solutions, as listed in the data table.
5. Using a new piece of red litmus for each solution, dip it into the solution and record the color that you observe.
6. Repeat step 5 with blue litmus paper. Dispose of all litmus paper in the trash.
7. Drop a pea-size amount of baking soda into each of the solutions. Record your observations.
8. Clean and rinse the test tubes. Repeat steps 3 and 4. Drop a small piece of magnesium into each test tube and record your results.
9. Before leaving the laboratory, clean up all materials and wash your hands thoroughly.
Collecting and Analyzing the Data
|Solution |Observations |
| |Litmus |Soda |Mg |
|Vinegar | | | |
|Lemon juice | | | |
|Carbonated water | | | |
|Washing soda | | | |
|Baking soda | | | |
|Soap | | | |
|Unknown | | | |
1. What pattern do you notice for the solutions in the first three test tubes?
2. What patterns do you notice for the solutions in the other three test tubes?
Drawing Conclusions
3. Solutions in the first three test tubes are acids. Solutions in the last three test tubes are bases. How is each group similar?
4. Use your data to classify the unknown as an acid or a base. State evidence for your answer.
Handout 2: Fill out the Ionization Process (I made it)
Ionization of common acids
|Acid |Ionization Process |
|HCl |HCl → H+ + Cl- |
|H2SO4 |H2SO4 → 2H+ + SO42- |
|HNO3 |HNO3 → H+ + NO3- |
|H2CO3 |H2CO3 → H+ + HCO3- → 2H+ + CO32- |
|CH3COOH |CH3COOH → H+ + CH3COO- |
Ionization of common bases
|Base |Ionization Process |
|NaOH |NaOH → Na+ + OH- |
|KOH |KOH → K+ + OH- |
|Ca(OH)2 |Ca(OH)2 → Ca2+ + 2OH- |
|Ba(OH)2 |Ba(OH)2 → Ba2+ + 2OH- |
|Mg(OH)2 |Mg(OH)2 → Mg2+ + 2OH- |
|NH3 |NH3 + H2O → NH4+ + OH- |
Handout 3 (I made it)
Activity 22.2 Strength of acids and bases in aqueous solution (20min.)
Purpose: To describe the concentration and acidity of acids and to classify weak and strong acids.
Procedure
[pic]
A B
1. See the diagrams that have molecular and ionic models in a container.
2. Count the total number of acid molecules that were added to water in each container.
3. Count the total number of hydrogen ions that are in water of each container.
4. Calculate the degree of ionization with the following equation.
Degree of ionization = (the total number of hydrogen ions in water)/(the total number of acid molecules added to water)
Collecting and Analyzing the Data
| |A |B |
|The total number of acid molecules added to | | |
|water | | |
|The total number of hydrogen ions in water | | |
|Degree of ionization | | |
|Acidity | | |
Drawing conclusions
1. What causes an acid to be acidic?
2. What does the acidity of a solution depend?
3. Which one is a strong acid? Why?
Handout 4 (I made it)
Neutralization of acids and bases: Fill out the vacancy with appropriate numbers and chemical formulas.
① HNO3 + (KOH) → KNO3 + H2O
② 2HCl + Mg(OH)2 → MgCl2 + (2H2O)
③ (H2SO4) + 2NaOH → Na2SO4 + 2H2O
④ 2HClO4 + (Ca(OH)2) → Ca(ClO4)2 + 2H2O
Handout 5 ( I made it.)
Activity 22.2 Neutralization reaction and pH change. (30min.)
Purpose: Describe the changes in a neutralization reaction in terms of temperature, pH and color of an indicator.
Procedure
1. Prepare HCl and NaOH solutions of the same concentration with large beakers from the teacher’ table. Then measure the temperatures of the solutions.
2. With a graduated 20mL cylinder, measure the volume of each solution and pour it to the Styrofoam container as listed in the data table.
3. Mix well two solutions and measure the temperature of the mixed solution. Record the temperature in the data table.
4. Then dip small strip of pH paper into the mixed solution. Compare the changed color to the color reference chart on the side of the container. Record the pH in the data table.
5. Drop BTB solution into the mixed solution and observe the color. Record the color in the data table.
6. Repeat the whole step with different volume of each solution as listed in the data table.
Collecting and Analyzing the Data
|Solution No. |Volume of HCl (mL)|Volume of NaOH (mL) |Temperature ((C) |pH |Color of BTB |
|1 |40 |0 | | | |
|2 |30 |10 | | | |
|3 |20 |20 | | | |
|4 |10 |30 | | | |
|5 |0 |40 | | | |
1. Which solution shows the highest temperature?
2. Which solution is acidic?
3. Which solution is neutral?
4. Which solution is basic?
5. What color is for BTB in acidic solutions?
6. What color is for BTB in basic solutions?
7. What color is for BTB in neutral solutions?
Drawing conclusions
8. Why some solution is still acidic or basic?
9. What causes the temperature to rise?
10. Which solution is neutralized perfectly?
11. How do we know which solution is neutralized perfectly?
Handout 6
Ionic model of neutralization reaction
Purpose: Explain the change in a neutralization reaction with ionic models.
Procedure: Examine the diagrams and answer the questions.
Step 1.
[pic]
1. What is in the beaker?
2. Is the solution in the beaker acidic or basic? Why?
3. What is in the spoid?
Step 2.
[pic]
4. Is the solution in the beaker acidic or basic? Why?
5. What happened during the step 1?
Step 3
[pic]
6. Is the solution in the beaker acidic or basic? Why?
7. What kind of salt is in the beaker?
Step 4
[pic]
8. Is the solution in the beaker acidic or basic? Why?
(4) Activities
• Group work: Strength of acids and bases
• Laboratory experiments
1. Activity 22.1 Properties of acids and bases in aqueous solution (Textbook p. 544) See handout 1
2. Activity 22.2 Neutralization reaction. See handout 5
• Demonstrations
1. Disappearing ink
2. Removing the shell from a raw egg without breaking the egg.
3. Cabbage juice indicator.
(F) Homework
• Homework 1:research about the uses of common acids and bases in our life.
• Homework 2: solve the problems of lesson review 22.1 (Textbook p.549)
• Homework 3: solve the problems of lesson review 22.2(Textbook p.556) and chapter review (Textbook p. 562~563)
• Readings: Physical Science, the Challenge of Discovery, Heath. Chapter 22. p. 540~563)
(G) References
• Textbook: Carle, Sarquis, Nolan, 1991, Physical Science, The Challenge of Discovery, D.C. Heath and Company, Lexington, Massachusetts.
•
•
•
•
-----------------------
Miha Lee
Lesson Plan
Chapter 22. Acids, Bases and Salts
Subject: 8th grade Physical Science
18th Week (5 periods)
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Miha Lee’s Chemistry Lesson Plan
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