Acids And Bases Unit - Weebly
Acids and Bases UnitJames Jin Park
James Jin ParkCHEM495Acids and Bases Unit PlanTopics/Units students will have covered: Chemical reactions Balancing chemical equations Solutions BondingFundamental Ideas: Acids and Bases have different characteristics and properties There are different models of acids and bases (primarily use the Bronsted‐Lowry Model) Strong acids and bases dissociate fully, whereas weak acids and bases do not Neutralization reactions: acids and bases react to for a salt and water Water is an amphoteric substance that can act as an acid or a base, or a neutral solution(pure) The pH scale is a convenient tool to represent a solution’s acidity/basicityOver‐riding Questions: What is an acid? What is a base? What are conjugate acid‐base pairs? How do strong acids and bases differ from weak acids and bases? What is the pH scale and how does that work in conjunction with indicators? How do we calculate the acidity/basicity of a solutionStudent Conceptions: Acids are the bubbly, green steaming solutions as depicted in pop culture Acids are harmful and poisonous for humans Acid and Base strength (strong/weak) and concentration means the same thing.
Color Key for Unit Instruction:‐Assessments‐Computer Activities‐Classroom Activities‐Laboratory ActivitiesStarting the Unit: Playing with pH paper: Bring household liquids and have the students test pH using pHpaper strips; possibility of using other indicators?o Students record the pH levels, observations, and physical properties andcharacteristics of the acids/bases (important later)o Exposure to real‐life uses of acids and baseso http://www.orientaldetox.com/ph‐of‐foods.htmlo e.htmo http://www.angelfire.com/az/sthurston/acid alkaline foods list.htmlUnit Instruction/Teaching Notes:1. What is an Acid? What is a Base?a. Physical/Chemical Propertiesi. Taste and feelii. Reacting with Indicators1. Don’t go into specifics of pH yetiii. Real‐life examples1. Incorporate discussion with Playing with pH paperlab activityb. The definition of acids and basesi. Arrhenius definition: depend on which ions were produced1. Limitation due to only allowing OH‐ ions for baseii. Bronsted‐Lowry definition: proton donor/acceptor (use this one)1. Conjugate acid‐base pairsiii. Di/Triprotic Acids2. Strong and Acids and Basesa. Strong acids completely ionize/dissociateb. Weak acids do not dissociate fullyc. Conductivity test with Strong and Weak Acids and Basesi. http://www.ehow.com/how 4493757 do‐water‐conductivity‐experiments.htmlii. olutionConductivity.htmd. Strong and weak bases dissociate similarly to strong and weak acids
i. PHET Acid‐Base Solutions cid‐base‐solutions1. 02. 63.4.5.6.7.8.e. Examples of strong and weak acids and basesQuiz over properties of acids and bases (matching), Bronsted‐Lowry definition withconjugate acid‐base pairs, strong/weak acids and basesNeutralization Reactionsa. Definition: acid and base mix to produce salt and waterb. Double replacement reactionsc. Molecular equations and neutralization problemsd. Titrationsi. Indicator necessaryii. Titration calculations to determine concentrations and volumese. CHEM101 UIUC Find Molar Mass labWatera. Amphoteric substance: behave as acid or baseb. Ion‐product constant: Kw 1.0E‐14 [H ][OH‐]c. Comparing the concentrations of hydrogen and hydroxide ions in a solutionpH scalea. place real‐life examples on pH scaleb. pH ‐log[H ], power‐of‐ten‐changec. pOH scale and pH ‐log[OH‐]i. Find pH and pOH using only strong acids and basesii. calculations of pH and pOH and using the ion‐product constantd. Water, Wine, Milk, Beer(Apple Juice) Demoi. wwmbdemo.htmii. b‐nope/Real Life Connections: Antacid LabFinal Assessment :a. Summative Assessmenti. Acid/Base properties, conjugate acid‐base pairsii. pH/pOH calculations, titrations and neutralization reactions
Classroom Demonstrations:Conductivity test with Strong and Weak AcidsMaterials: battery light bulb with metal tabs coming out from the bottom) three wires with alligator clips at each end. 3 beakers Distilled/deionized water A strong and weak acidSetting Up the Conductivity Tester:Clip on alligator clip to the negative battery end, leaving the other end of the wirehanging loose. Clip a second alligator clip to the positive end, then clip the opposite side of thatwire to the one tab on the light bulb. Clip the final alligator clip on the last remaining wire tothe other tab on the light bulb, leaving the opposite end of the wire hanging free.Purpose: To discern the different strengths of electrolytes by doing a conductivity test in water.This demonstration shows that distilled water is not a very good conductor, but whenelectrolytes dissociate in water, the solution can conduct electricity. The strength of an acid canbe shown through the brightness of the light bulb.The Demonstration: Set up the conductivity tester. Fill one beaker with deionized(DI) water and place the two end of the circuit intoopposite ends of the beakers to show that DI water is a poor conductor Grab another beaker and fill it up half way with DI water and place some strong acid inthe beaker. Make sure the strong acid dissolves, and then run the conductivity test Grab another beaker and fill it up half way with DI water and place some weak acid inthe beaker. Make sure the weak acid dissolves, and then run the conductivity testExplanation of the Demonstration:Pure water doesn’t have many ions, so the number of charged particles in pure water isvery low. Strong acids dissociate fully, so adding a strong acid solution to DI water will create asolution with more ions than it had before. The same thing happens for weak acids, but sinceweak acids do not dissociate fully, there will be less ions in the solution if both solutions startedwith the same number of moles of the acid. Make sure to test both the strong acid and weakacid and the amount of acid used, because the results could change depending on the amountof water used for the demonstration.
Discussion Questions: Before starting any of the conductivity tests:o What is electricity?o I have set up a conductivity tester. What do you think will happen to the lightbulb when I try to test of the conductivity of this distilled water? After testing the conductivity of the water and before testing the strong acid in solution:o Did anything happen to the light bulb?o What do we know about strong acids when they are placed in water?o If I were to put a strong acid into this distilled water, what will happen to thelightbulb? After testing the conductivity of the strong acid and before testing the weak acid insolution:o Did anything happen to the light bulb? Is that what we expected?o What do we know about weak acids when they are placed in water?o What do you think happen when we do the same test with a weak acid? After testing the conductivity of the weak acid:o What happened to the light bulb? Does is look different than when we used thestrong acid?o What could we use this conductivity test for?Discussion Questions (Key): Before starting any of the conductivity tests:o What is electricity? Electricity: flow of moving electrons; simply the movement of electronso I have set up a conductivity tester. What do you think will happen to the lightbulb when I try to test of the conductivity of this distilled water? Explain that distilled water is essentially pure water if the students don’tknow. This is aguessing question so be prepared for different responses After testing the conductivity of the water and before testing the strong acid in solution:o Did anything happen to the light bulb? The light bulb should not light upo What do we know about strong acids when they are placed in water? The strong acid will dissociate fully; all of the strong acid will break upinto its individual ionso If I were to put a strong acid into this distilled water, what do you think willhappen to the light bulb?
This is a guessing question so be prepared for different responses. Mostlikely, that the light bulb will light upAfter testing the conductivity of the strong acid and before testing the weak acid insolution:o Did anything happen to the light bulb? Is that what we expected? If done correctly, the light bulb should light up brightly. Expectations willbe dependent on the students’ responses to that prior questiono What do we know about weak acids when they are placed in water? They dissociate, but not to the degree of strong acids. Not all of thehydrogen cations will be released into the solutiono What do you think happen when we do the same test with a weak acid? This is a guessing question so be prepared for different responses. Mostlikely that the light bulb will light up but not as brightly as it did with thestrong acidAfter testing the conductivity of the weak acid:o What happened to the light bulb? Does is look different than when we used thestrong acid? If done correctly, the light bulb will light up, but not as bright as before.o What could we use this conductivity test for? Various possible responses: testing the strength of an unknown acid orbase, seeing how many ions are in a solution (for example a pond)
Water, Wine, Milk, Beer(Apple Juice) DemonstrationMaterials: distilled water 4 glass cups for the different solutions Saturated sodium bicarbonate with 20% sodium carbonate solution with pH 9 phenolphthalein indicator Barium chloride solution (1.0 M) Either bromothymol blue or crystals of sodium dichromate Hydrochloric Acid (12 M)Purpose: To utilize multiple chemical reactions to create different solutions the resemble water,wine, milk, and beer. This demonstration can be done step‐by‐step to have so that students canwalk through the chemical reactions and discuss what is causing the different changes to occurfrom glass to glass.How to prepare the different glasses: GLASS#1: Create a sodium bicarbonate with sodium carbonate solution that has a pH of9. Do this by taking a 250 mL beaker, filling it to about 2/3 full, and then adding 20‐25mL of the sodium bicarbonate with 20% sodium carbonate solution. Test pH with pHstrips. This will be the water cup. GLASS#2: Place a few drops of phenolphthalein indicator at the bottom of the glass. Thiswill be the wine cup. GLASS#3: Pour about 5 mL of the BaCl solution into the bottom of the glass. This will bethe milk solution GLASS#4: This will be the beer/apple juice cupo If using the BROMOTHYMOL BLUE: Pour about 10 mL of the 12 M HCl into thefourth glass with a few drops of bromothymol blue indicator.o If using the crystals of SODIUM DICHRMOMATE: Place a few crystals at thebottom of the fourth glass. Add about 5 mL of the 12 M HCl into the glass priorto starting the demonstration.The Demonstration Start by showing the first glass which is the water glass. Pour the resulting solution from the water glass into the second glass to create the winesolution
Pour the resulting solution from the wine glass into the third glass to create the milksolutionPour the resulting solution from the milk glass into the fourth glass to create thebeer/apple juice solutionExplanation of the Demonstration:The starting solution should be a basic solution with a pH of 9. Adding phenolphthaleinto the solution will turn it purple because it is a basic solution. When the solution is then addedto the barium chloride, Barium hydroxide will precipitate out, causing the solution to look likeopaque white liquid. Since some of the hydroxide ions are precipitated out of the solution, theconcentration of hydroxide ions will decrease and the solution will be less basic; this causes thepink color to disappear. When adding the milk solution to the glass with the bromothymol blueindicator and the hydrochloric acid, the solution will become more basic and the indicator willcause the solution to become a brown color. When adding the mild solution to the glass withthe sodium dichromate crystals and the hydrochloric acid, the resulting reaction will give offCO2 and the reaction will turn a brown color.Discussion Questions: Before starting the demonstrationo What can you say about this solution?o What do you think will happen when I pour this solution into Glass#2? After pouring the starting solution in glass#1 into glass#2:o What happened to the solution?o Why did starting solution change color?o Because of the resulting solution, what do we know about the initial solution?o What do you think will happen when I pour this solution into Glass#3? After pouring the wine solution into glass#3:o What happened to the solution?o Since the solution isn’t a transparent purple anymore, what do you think is insidethe new solution?o Why is the new solution white and not purple anymore?o What do you think will happen when I pour this solution into Glass#4? After pouring the milk solution into glass#4:o What happened to the solution?o Why is the solution brown and not white like it was before?
Discussion Questions (Key): Before starting the demonstrationo What can you say about this solution? Various responses: it’s clear, it’s a little cloudy, it’s colorless andtransparento What do you think will happen when I pour this solution into Glass#2? Various responses. This is a guessing question so be prepare for differentresponses After pouring the starting solution in glass#1 into glass#2:o What happened to the solution? If done correctly, the solution should still be transparent, but purpleo Why did starting solution change color? Phenolphthalein indicator at the bottom of glass#2 caused the solution toturn purpleo Because of the resulting solution, what do we know about the initial solution? The initial solution was basic (solution has a pH of 9)o What do you think will happen when I pour this solution into Glass#3? Various responses. This is a guessing question so be prepare for differentresponses After pouring the wine solution into glass#3:o What happened to the solution? If done correctly, the solution should be a milky white color. The pinkshould be mostly gone, and the solution should no longer be transparento Since the solution isn’t a transparent anymore, what do you think is inside thenew solution? A precipitate was formed. The BaCl reacted with the starting solution toyield Ba(OH)2 which is insoluble and it will become the precipitate.o Why is the new solution white and not purple anymore? Less concentration of OH‐ ions will make the solution more acidic than itwas before, so the pH will decrease and the purple will disappearo What do you think will happen when I pour this solution into Glass#4? Various responses. This is a guessing question so be prepare for differentresponses After pouring the milk solution into glass#4:o What happened to the solution? The resulting solution turned brown; bubbles will also form if the sodiumdichromate crystals are used.o Why is the solution brown and not white like it was before?
If bromothymol blue is used: bromothymol blue turns brown in an acidicsolution, and the large amount of concentrated HCl made the resultingsolution acidicIf using sodium dichromate crystals, a chemical reaction will occur andcarbon dioxide will form. The reaction will cause the solution to turn intoa brown color.
Laboratory Experiments:NAMEPlaying with pH PaperIntroduction:In our everyday lives, we come into contact with many different acidic and basic products. Inorder to test how acidic or basic something is, scientists like to use the pH scale. If a substancehas a pH less than 7, then it is considered acidic. If a substance has a pH greater than 7, then isit considered basic (also known as alkaline). If a substance has a pH of 7 means that thesubstance is neutral. Many products that we use daily for personal hygiene, home and autocare, or eating and drinking are suitable for pH testing. For this activity, we will be using stripsof pH paper to test the pH levels of some of these products.Materials: Strips if pH paper with pH scale Different products to test pH Glass rodsProcedure:Prior to testing the pH levels of the different products, predict what the pH levels will befor each product. In order to test the pH levels of the different products, take a clean glass rodand dip it into the substance. After dipping the glass rod, remove the glass rod and touch a stripof pH paper with it. Record the real pH of the product.Data:SubstancePredicted pHActual pH
Lab Questions:1. State which, if any, pH values surprised you. Why were you surprised?2. What do you notice about the pH levels of cleaning supplies?3. Do the foods we eat and drink have a small range of pH levels or large range of pH levels?Considering that the pH level of blood is about 7.34‐7.45, did you expect this?4. Acids are often thought to be corrosive. Explain why the pH level of our stomach acid isabout 1.
NAMEPlaying with pH Paper (KEY)Introduction:In our everyday lives, we come into contact with many different acidic and basic products. Inorder to test how acidic or basic something is, scientists like to use the pH scale. If a substancehas a pH less than 7, then it is considered acidic. If a substance has a pH greater than 7, then isit considered basic (also known as alkaline). If a substance has a pH of 7 means that thesubstance is neutral. Many products that we use daily for personal hygiene, home and autocare, or eating and drinking are suitable for pH testing. For this activity, we will be using stripsof pH paper to test the pH levels of some of these products.Materials: Strips if pH paper with pH scale Different products to test pH Glass rodsProcedure:Prior to testing the pH levels of the different products, predict what the pH levels will befor each product. In order to test the pH levels of the different products, take a clean glass rodand dip it into the substance. After dipping the glass rod, remove the glass rod and touch a stripof pH paper with it. Record the real pH of the product.Data:A few examples of different substance and their pH levels. This chart depends on whichproducts were used for this laboratory activitySubstanceCoca‐ColaBlack CoffeeLemon JuiceMilkAmmoniaLiquid PeptoBismolToothpasteLaundry detergentSoapPredicted pHActual pH252.36.811.63‐48‐108‐108‐10
Lab Questions:5. State which, if any, pH values surprised you. Why were you surprised?These are based upon the predictions of the students6. What do you notice about the pH levels of cleaning supplies?Cleaning supplies tend to be alkaline in nature7. Do the foods we eat and drink have a small range of pH levels or large range of pH levels?Considering that the pH level of blood is about 7.34‐7.45, did you expect this?We eat and drink different foods of a relatively wide range of pH levels.Expectations are based on the opinions of the students.8. Acids are often thought to be corrosive. Explain why the pH level of our stomach acid isabout 1.We start the chemical digestion of food in our stomach. Stomach acid needs to be concentratedand corrosive to help break down the proteins that enter our stomach.
NAMEUnknown Weak Acid LabIntroduction:A simple definition of an acid is a species that dissociates in water to release hydrogen ions (H ).An acid such as this will react with a metal hydroxide (such as sodium hydroxide, which is a base)to form a salt and water. The general reaction can be symbolized as:HA (aq) NaOH (aq) NaA (aq) H2OThis is why acid‐base reactions are often called neutralization reactions. Chemical indicators areoften used to determine when a reaction has gone to completion.In this lab, you will be given approximately 0.1 M NaOH and a
e. Examples of strong and weak acids and bases 3. Quiz over properties of acids and bases (matching), Bronsted‐Lowry definition with conjugate acid‐base pairs, strong/weak acids and bases 4. Neutralization Reactions a. Definition: acid and base mix to produce salt and water b. Double replacement reactions
2. Describe the common properties of acids and bases 3. Identify acids and bases using indicators, pH papers 4. Name some common lab acids and bases, acids at and bases at home 5. Describe reactions of acids with metals, bases and carbonates 6. Describe the application of acids, bases and p
_7. Which statement describes an alternate theory of acids and bases? (1) Acids and bases are both H acceptors. (2) Acids and bases are both H donors. (3) Acids are H acceptors, and bases are H donors. (4) Acids are H donors, and bases are H acceptors. _8. Which substance is the
Properties of Acids and Bases Return to the Table of contents Slide 5 / 208 What is an Acid? Acids release hydrogen ions into solutions Acids neutralize bases in a neutralization reaction. Acids corrode active metals. Acids turn blue litmus to red. Acids taste sour. Properties of Acids Slide 6 / 208 Properties
Unit 12 Acids and Bases- Funsheets Part A: Name and write the formula for the following acids and bases. 1) Carbonic acid _ . Part E: Using your knowledge of acids and bases, answer the following questions. 1) Fill in the following Venn diagram about properties of acids and bases. You must fill in at least 4 facts in each.
Unit 11 Objectives: Acids & Bases Acid-Base Nomenclature Content Objectives: I can name ionic compounds containing acids, and bases, using (IUPAC) nomenclature rules. I can write the chemical formulas of acids and bases. Criteria for Success: I can identify an acid as a binary acid or an oxyacid. I can name common binary acids, oxyacids, and bases given their chemical formula.
Unit 14 – Acids & Bases 1 Worksheets - Honors BRONSTED - LOWRY ACIDS & BASES WORKSHEET According to Bronsted-Lowry theory, an acid is a proton (H 1) donor, and a base is a proton acceptor. Label the Bronsted-Lowry acids (A), bases (B), conjugate acids (CA), and conjugate bases (CB) in the
properties of acids and bases. 5. Describe the colors that form in acidic and basic solutions with litmus paper and phenolphthalein. 6. Explain the difference between strong acids or bases and weak acids or bases. 7. Memorize the strong acids and bases. 8. Define the terms polyprotic and amphiprotic. 9. Perform calculations using the following .
Acids, Bases, and pH The hydrohalic acids (HX (aq)), where X represents a halogen) include HF, HCl, HBr, and HI. Only HF is a weak acid. The rest are strong acids. What factors account for this difference? 8.1 Explaining the Properties of Acids and Bases 8.2 The Equilibrium of Weak Acids and Bases 8.3
