ACID BASE TEST (2 nd half of class) Acid-base titration lab 2 nd half. Chapter 18 Acids and Bases Campbell Chemistry Name

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1 Date In Class 3/31 Thurs. Equilibrium Test Homework (to be done that night, or before coming to the next class) Watch Acid Base Video 1. What are Acids and Bases? 4/1 Fri Video 1 discussion: Identifying acids and bases and Conjugate acids and bases Over Weekend: Watch video 2. Acid and Base Strength 4/4 Mon. Calculating ph 4/5 Tues Weak Acids and Bases and Calculating Ka Watch Video 3. Titrations and Neutralization Calculations Complete Acid Base Titration Prelab 4/6 Wed Vinegar Titration Lab 4/7 Thurs Work on Acid Base Calculations 4/8 Fri EOC Schedule: 1 st 8: th 10:06 12:20 7 th 12:26-2:10 6 th 2:16-3:05 4/11 Mon LSM 3 rd 9:46-11:30 4 th 11:36-12:55 2 nd 1:01-1:36 5 th 1:42-2:17 7 th 2:23-3:05 4/12 Tue 1 st 8:16-9:05 2 nd 9:11-10:55 4 th 11:01-1:15 6 th 1:21-3:05 4/13 Wed. 2 nd 8:16-9:05 3 rd 9:11-10:55 5 th 11:01-1:15 7 th 1:21-3:25 4/14 Thurs 3 rd 8:16-9:05 1 st 9:11-10:55 4 th 11:01-1:15 6 th 1:21-3:05 4/15 Fri 1 st 8:16-8:53 2 nd 8:59-10:43 3 rd 10:49 11:26 5 th 11:32-12:51 4 th 12:57-1:33 6 th 1:39 2:15 7 th 2:21-3:05 Watch Video 4 Salt Hydrolysis Bring Headphones!!! Salt hydrolysis Activity Work on Packet (5 th -35 min. and 7 th 49 min) Work on Packet (1 st half) Review for test (2 nd half) (6 th min) 5 th and 7 th hours (104 min each) Review (1 st half of class) and ACID BASE TEST (2 nd half of class) 6 th hour (104 min) ACID BASE TEST (1 st half of class) Acid-base titration lab 2 nd half 5 th & 7 th Acid-base titration lab 6 th test corrections etc. Study for Chapter 18 Test 1

2 Video 1. Acid Base Introduction and Definitions Textbook: Chapter 18: pages Guided Notes for Video on Acid Base Introduction and Definitions Questions: What are the properties of acids and bases: Property Acid Base Taste: Feel: Litmus Paper Color: What is Arrhenius Definition of: an Acid: a Base: What is wrong with Arrhenius definition? What is the Bronsted-Lowry Definition of: An Acid: A Base: How do you tell which reactant is the acid? And which is the base? HCl (g) + H 2O (l) Cl - (aq) + H 3O + (aq) What is a hydronium ion? Identify the acid and base in this reaction: NH 3(g) + H 2O (l) NH 4 + (aq) + OH - (aq) What is an amphoteric substance? What are two examples of amphoteric substances? What is a Conjugate Acid? (turn page) 2

3 What is a Conjugate Base? What side of a reaction do the conjugate acid and base pairs occur on? Label the acid, base and conjugate acid and base in the following reactions: HCl + H 2O H 3O + + Cl - NH 3 (g) + H 2O (l) NH 4 + (aq) + OH - (aq) HCN (aq) + SO 4 2- (aq) «HSO 4 - (aq) + CN - (aq) CH 3COO - (aq) + H 2S (aq) «CH 3COOH (aq) + HS - (aq) 3

4 Video 2. Acid and Base Strength Textbook: Chapter 18: page , Guided Notes for Video on Acid Base Strength Acid Naming Review: When do you use hydro when naming acids? Give an example using HCl and HClO 3 Questions: What is a strong Acid or Base? How is a weak acid or base different from a strong one? List the 7 strong acids List the 7 strong bases: What is a ph scale? Solutions with a ph of less than 7 are: Equal to 7 are: Greater than 7 are: In a neutral solution how does the hydrogen ion concentration compare to the hydroxide ion concentration? What is the hydrogen ion or hydroxide ion concentration equal to in strong acids and bases? What is the mathematical equation for calculation ph? 4

5 In Class Notes for Calculating ph 1. What is a log? 2. What are the steps for calculating ph? Use the [H + ] = 6.8x10-3 M as your example: 3. Write the equation and calculate the ph of each of the following: a. If [H + ] = 1.0 x 10-5 M b. If [H + ] = 5.20 x M c. If the HCl concentration is 0.05 M what is the ph? 4. What are the steps for calculating the[h + ] from ph? 5. Calculate the following: a. What is the [H + ] if the ph is 4? b. What is the [H + ] if the ph is 2.3? c. What is the [H + ] if the ph is 14.5? 6. How do you calculate the ph if you are given an OH- concentration? 7. Calculate the following: a. What is ph of a 0.006M solution of NaOH? b. What is the ph of a 1.5x10-4 M solution of KOH? In Class notes on Ka Calculations (textbook chapter 18 pages ) 1. Write the disassociation equation for the make believe acid HA 2. Using the equation above write the Keq (called Ka for acids) for this reaction. 3. How can you tell from a Ka value how strong an acid is? 5

6 4. Which acid is the strongest? Which is the weakest? Acid Name Ka 5. What are the steps for calculating Ka? 6. Show steps and calculate the following: a. A solution of HA has an equilibrium concentration of 1M. At equilibrium the H + and A- concentration is 0.2 M. What is the Ka? b. Determine the concentration of [H+] and the ph in a bottle which contains M HC2H3O2 The Ka is 1.74 x c. A hydroflouric acid solution, HF (aq), has a Ka of 1.3 x What is the ph if the equilibrium concentration of the hydrofluoric acid solution is M? 6

7 Video 3. Titrations and Neutralization Calculations Textbook: Chapter 18: pages Guided Notes for Video on Titrations Questions: What is a titration? What is a standard solution? What does neutralization mean? What is an equivalence point? What is an indicator? When using a buret in lab to titrate, what decimal place should you record to? What happened to the ph of the NaOH solution as I added HCl to it? What is the equation for calculating neutralization problems? What do each variable represent? Show your work for each of the following: What is the molarity of 10.0 ml of sodium hydroxide base, if it is neutralized by 13.0 ml of M HCl? If mls of M solution of NaOH is required to neutralize mls of an H 2SO 4 solution, what is the molarity of the sulfuric acid solution? 7

8 Video 4. Salt Hydrolysis Textbook: Chapter 18: page 665 Guided Notes for Video on Salt Hydrolysis What is a salt? Questions: How do you know if a salt is: Neutral: Acidic: Basic: Don t forget your list of strong acids and bases, its on page 4 What are the steps to determining if a salt with be acidic, basic, or neutral? Show steps and determine if acidic, basic, or neutral for the following salts: 1. NaCl 2. Mg(NO 3) 2 3. Ba(C 2H 3O 2) 2 4. NaBr 5. CuClO 3 8

9 In Class Work for Video 1: 1. For each description below, write acid if it tells about a property of an acid or base if it tells about a property of a base. a. Turns litmus paper blue d. Feels rough b. Feels slippery c. Turns litmus paper red e. Tastes bitter f. Tastes sour 2. What is the difference between the Arrhenius definition and Bronsted-Lowry definition of acids and bases? 3. In each of the following equations, identify the acid, base, and conjugate acid and base. a. HSO H 2O SO H 3O + b. CH 3NH 2 + HCl CH 3NH Cl - c. CH 3COO - + H 2O CH 3COOH + OH - 4. Complete the following, Name each as: acid, base, conjugate acid, or conjugate base. Also identify any amphoteric substances in the table. The first is finished for you. a. HF + H 2O F - + H 3O + Acid base conjugate base conjugate acid b. OCl -1 + H 2O + C HNO 2 + ClO d. CO HF + e. CN -1 + HBr + f. PO HCl + g. PO HNO 3 + h. H 2PO OH

10 In class work for video 2 and in class work on ph Calculations: 5. Explain the difference between a strong acid and a weak acid. 6. What is true of the OH - and H + concentrations in pure water? 7. Explain why equilibrium arrows (double sided arrows) are used in the ionization equations for some acids. 8. Solution A has a ph of 2.0. Solution B has a ph of 5.0. Which solution is more acidic? Based on the H + ion concentration in the two solutions, how many times more acidic? 9. Using the table below, answer the following questions. a. Which substance is most basic? b. Which substance is closest to neutral? c. Which substance has a poh of 11.0? Substance ph Household ammonia 11.3 Lemon Juice 2.3 Antacid 9.4 Blood 7.4 Soft drinks 3.0 d. How many times more acidic is blood than antacid? 10. What is the ph of a solution in which [H + ] = 4.5 x 10-4 M? 11. What is the ph of a M H 2SO 4 solution? 12. What is [H + ] in a solution having a: a. ph of 2.9? b. ph of 5.2? c. ph of 1.3? 13. Calculate the ph of a solution with: a. [H + ] = 3.6 x 10-9 M b. [H + ] = 2.5 x 10-2 M c. [H + ] = 6.5 x 10-4 M d. [H + ] = 1.0 x 10-6 M e. [H + ] = 3.3 x 10-5 M 14. What is [H + ] in a solution having a: a. ph of 3.9? b. ph of 5.6? c. ph of 2.3? d. ph of 4.1? 10

11 15. What is the ph of a solution with an [OH-] concentration of: a. 5.8 x 10-4 M b M c x 10-8 M d x 10-3 M e M In Class Practice Weak Acid and Base 16. If the acid ionization constant is very small, what would be the relative concentration of H + ions? Would this be a strong or weak acid? 17. Why we must use K a when calculating the ph of a weak acid, but we do not use K a when calculating the ph of a strong acid. 18. Rank the following acids from strongest to weakest based on their K a value. Citric acid (K a = 3.2x10-7 ) Formic acid (K a = (1.8x10-4 ) Benzoic acid ( K a = 6.4 x10-5 ) Boric acid ( K a = 5.4x10-10 ) 19. For each of the following, write a dissociation (chemical) equation. a. The dissociation of solid magnesium hydroxide in water. b. The ionization of propanoic acid (HC 3H 5O) in water. 20. A hydrofluoric acid solution has an equilibrium concentration of M. What is the K a of the solution if the equilibrium concentrations of [H + ] and the [F - ] both equal 6.57 x 10-3 M? 21. Determine the experimental equilibrium constant, K a, of an acetic acid solution if the equilibrium concentration is M acetic acid and the hydronium ion concentration is moles/liter. 22. A M solution of a weak acid (HA) has a hydronium ion concentration is 7.24 x10-4 moles/liter. What is the Ka of the acid? 11

12 23. The K a for HCN = 6.31 x Calculate the equilibrium concentrations of the hydronium ion and cyanide ion from a M solution of the acid. 24. Hydrocyanic acid, HCN, is a weak acid with a K a = 4.9 x What is the ph of HCN if it s concentration at equilibrium is M? milliliters of a solution contains 15.5 grams of acetic acid. Its ionization constant, K a = 1.8 x Calculate the [H + ] and the ph of the solution. (Assume the acetic acid is at equilibrium.) In Class work on Titration and Neutralization 26. When an acid reacts with a base, what products are formed? 27. In a laboratory experiment, ml of an aqueous ammonium hydroxide solution is titrated to neutralization using ml of a M HCl solution. What is the concentration of the aqueous ammonium hydroxide solution? 28. What is the concentration of a NaOH solution if ml is required to completely neutralize ml of a 1.50 M solution of HNO 3? 29. How many mls of M H 2SO 4 are required to neutralize 75 ml of M Al(OH) 3? 30. What is the molarity of H 2CO 3 if ml of M KOH solution is needed to neutralize ml of the acid solution? 31. What is the concentration of Fe(OH) 3 if ml of M H 2SO 4 is required to neutralize ml of the solution? 32. What volume of.250 M H 3PO 4 is needed to neutralize 43.5 ml of.685 M Cu(OH) 2? 12

13 33. What is the molarity of 1.25 L of NaOH if it takes.650 L of 1.45 M H 2SO 4 to completely neutralize it? In Class Work on Salt Hydrolysis 34. Write the terms, acidic, basic, or neutral in the blanks below. Acidic, Basic, and Neutral Salts: Examples Salt Parent Acid Parent Base ph of the salt solution KC 2H 3O 2 HC 2H 3O 2 (weak) KOH (strong) ph >7 (basic) NaCl HCl (strong) NaOH (strong) ph = 7 (neutral) NH 4Cl HCl (strong) NH 4OH (weak) ph <7 (acidic) 35. Give the parent acid, parent base, and ph range of the salt solution for each of the following: Salt Parent Acid Parent Base ph of the salt solution (acidic, basic, or neutral) a. Na 3PO 4 b. MgCl 2 c. FeCl 2 d. KNO 3 e. Ba(ClO 3) 2 f. NaNO 2 g. NaC 2H 3O 2 h. CuI 2 i. Li 2SO 4 j. AlCl 3 13

14 Additional Acid Base problems 36. What is the ph if you dissolve 25.5 grams of hydrochloric acid in 1250 ml of total solution? 37. What volume of a.648 M solution of HClO 3 would be needed to neutralize 34.7 ml of a.27 M solution of Ba(OH) 2? 38. What is the ph if the molarity of HF at equilibrium is.35 M? The K a of HF = 6.3 x What is the molarity of a solution of LiOH if ml are neutralized by ml of.372 M HNO 3? 40. Nomenclature: Provide the name or formula for the following compounds: Li 2S HC 2H 3O 2 Hydrosulfuric acid Copper (II) sulfite Ca(NO 2) 2 H 2Se Sulfurous acid Potassium acetate Sn(OH) 4 H 2CO 3 Chloric acid Barium chlorite PbS C 2S 4 Trinitrogen pentasulfide Iron (III) nitrate Cu 3PO 4 IBr 6 Sulfur heptachloride Mercury (II) nitride 14

15 Selected answers 1 a. base b. base, c. acid, d. acid, e. base, f. acid 3 a) A + B = CB + CA b) B + A = CA + CB c) B + A = CA + CB 6) Equal 7) weak acids and bases are reversible reactions 8) H A= 0.01, H B = , 1000x 9a. ammonia 9b. blood 9c. soft drinks 9d. 100x a b x c a b c d e a b x c d x a b c d e ) formic > benzoic > citric > boric 19) a) Mg(OH) 2 Mg OH - b) HC 3H 5O H + + C 3H 5O x x x x 10-6 M [H + ] =.00378, ph= salt and water M M ml M M ml M 34a. neutral b. acid c. base 35a. basic 35b. acidic 35c. acidic 35d. neutral 35e. basic 35f. basic 35g. basic 35h. acidic 35i. neutral 35j. acidic 36. ph = ml 38. ph = M Li 2S: Lithium Sulfide Ca(NO 2) 2 Calcium nitrite Sn(OH) 4 Tin (IV) hydroxide PbS Lead (II) Sulfide Cu 3PO 4 Copper (I) phosphate HC 2H 3O 2 Acetic Acid H 2Se Hydroselenic Acid H 2CO 3 Carbonic Acid C 2S 4 Dicarbon tetrasulfide IBr 6 Iodine hexabromide Hydrosulfuric acid H 2S Sulfurous acid H 2SO 3 Chloric acid HClO 3 Trinitrogen pentasulfide N 3S 5 Sulfur heptachloride SCl 7 Copper (II) sulfite CuSO 3 Potassium acetate KC 2H 3O 2 Barium chlorite Ba(ClO 3) 2 Iron (III) nitrate Fe(NO 3) 3 Mercury (II) nitride Hg 3N 2 15