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Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
Acids and Bases
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Acids and Bases

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  • Titration. (a) Before the titration begins, the liquid in the flask is colorless and clear. (b) At the endpoint a pole pink color persists in the flask. (d) After the endpoint, the color of the solution turns bright pink, indicating an excess of base.
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    1. Chapter 15Foundations of College Chemistry, 13eJohn Wiley & Sons, IncMorris Hein and Susan ArenaAcids, Bases, and SaltsLemons and limes areexamples of food whichcontains acidic solutions.
    2. 15.1 Acids and Bases15.2 Reactions of Acids15.3 Reactions of Bases15.4 Salts15.5 Electrolytes andNonelectrolytes15.6 Dissociation andIonization ofElectrolytes15.7 Strong and WeakElectrolytes15.8 Ionization of Water15.9 Introduction to pH15.10 Neutralization15.11 Writing Net IonicEquations15.12 Acid Rain15.13 Colloids15.14 Properties of Colloids15.15 Applications ofColloidal PropertiesChapter OutlineCopyright 2011 John Wiley & Sons, Inc15-2
    3. Arrhenius Acids• Metals to produce H2 gas• Bases to produce salt and water• Carbonates to produce carbon dioxideCopyright 2011 John Wiley & Sons, Inc15-3Definition: An acid solutioncontains an excess of H+ions.Properties1. Sour taste2. Turn blue litmus red3. The ability to react with
    4. Arrhenius BasesCopyright 2011 John Wiley & Sons, Inc15-4Definition: A base solutioncontains an excess of OH-ions.Properties1. Bitter or caustic taste2. Turn red litmus blue3. Slippery, soapy feeling4. Neutralize acids
    5. Your Turn!Which type of solution would have a sourtaste and turn blue litmus red?a. Acidb. Basec. SaltCopyright 2011 John Wiley & Sons, Inc15-5
    6. Brønsted-Lowry Acids andBases An acid is a proton (H+) donor. A base is a proton (H+) acceptor.Copyright 2011 John Wiley & Sons, Inc15-6HCl(g) + H2O(l)  H3O+(aq) + Cl-(aq)H O ••••••••H+ ••H Cl ••••••Cl •••••••• -+H O ••••••••HH+BaseAcidConjugate BaseConjugate Acidhydronium ion
    7. Brønsted-Lowry Acids andBases Ammonia is a weak base that forms theammonium ion and the hydroxide ion in water. Conjugate acid-base pairs: NH4+ – NH3 andH2O – OH-Copyright 2011 John Wiley & Sons, Inc15-7NH3(aq) + H2O(l)NH4+(aq)+ H+ - H+OH-(aq)+OH-(aq)NH4+(aq)→→
    8. Your Turn! What is the conjugate acid of hydrogenphosphate?a. H2PO4-b. H3PO4c. H3PO4+d. HPO42-Copyright 2011 John Wiley & Sons, Inc15-8
    9. Your Turn! Which are the two Bronsted-Lowry acids inthe following equation? H2S + H2O HS - + H3O+a. HS - and H2Ob. H2S and HS -c. H2S and H3O +d. H3O + and H2OCopyright 2011 John Wiley & Sons, Inc15-9→→
    10. Lewis Acid-Base Definition A base is an electron pair donor. An acid is an electron pair acceptor.Copyright 2011 John Wiley & Sons, Inc15-10
    11. Three Acid-Base Theories Use the theory that best explains thereaction under consideration:Copyright 2011 John Wiley & Sons, Inc15-11
    12. Reactions of Acids Acids react with metals that lie above H inthe activity series: acid + metal  salt + hydrogen 2HCl(aq) + Mg(s)  MgCl2(aq) + H2(g) Acids react with bases (neutralization) acid + base  salt + water 2HCl(aq) + Ca(OH)2(aq) CaCl2(aq) +2H2O (l) Copyright 2011 John Wiley & Sons, Inc15-12
    13. Reactions of Acids Acids react with metal oxides acid + base  salt + water 2HCl(aq) + Na2O(s)  2NaCl(aq) + H2O(l) Acids react with metal carbonate acid + base  salt + water + carbondioxide 2HCl(aq) + Na2CO3(aq) 2NaCl(aq) +H2O(l) + CO2(g) Copyright 2011 John Wiley & Sons, Inc15-13
    14. Reactions of Bases Bases can be amphoteric as base: Zn(OH)2(aq)+ 2HBr(aq)  ZnBr2(aq) + 2H2O(l) as acid: Zn(OH)2(aq)+ 2NaOH(aq)  Na2Zn(OH)4(aq) NaOH and KOH react with metals base + metal + water  salt + hydrogen 2NaOH(aq) + 2Al(s) + 6H2O(l)  2NaAl(OH)4(aq) + 3H2O(g)Copyright 2011 John Wiley & Sons, Inc15-14
    15. Your Turn!What gas is produced by the reaction ofsodium bicarbonate with acetic acid?a. Hydrogenb. Carbon dioxidec. Nitrogend. OxygenCopyright 2011 John Wiley & Sons, Inc15-15
    16. Salts Salts are the result of acid-baseneutralization reactions. HCl(aq)+ NaOH(aq) NaCl(aq)+H2O(l) Salts are ionic compoundscomposed of a cation (usually ametal or the ammonium ion) andan anion (not oxide or hydroxide). Salts are usually crystals with highmelting and boiling points.Copyright 2011 John Wiley & Sons, Inc15-16
    17. Your Turn! What salt forms from the reaction ofmagnesium hydroxide and sulfuric acid?a. MgSb. Mg2Sc. MgSO4d. Mg2SO4Copyright 2011 John Wiley & Sons, Inc15-17
    18. Your Turn! What salt forms from the reaction ofaluminum oxide and hydrobromic acid?a. AlBrb. AlBr3c. Al2Brd. Al2Br3Copyright 2011 John Wiley & Sons, Inc15-18
    19. Electrolytes andNonelectrolytes Electrolytes are compounds whose aqueoussolutions conduct electricity. Nonelectrolytes are substances whose aqueoussolutions are nonconductors.Copyright 2011 John Wiley & Sons, Inc15-19
    20. Electrolytes andNonelectrolytes It is the movement of ions thatconduct electricity in water . Acids, bases and salts areelectrolytes because theyproduce ions in water whenthey dissolve.Copyright 2011 John Wiley & Sons, Inc15-20
    21. Dissociation of Electrolytes Salts dissociate into cations and anionswhen they dissolve in water. NaCl(s)  Na+(aq) + Cl-(aq)Copyright 2011 John Wiley & Sons, Inc15-21
    22. Ionization of Electrolytes Ionization is the formation of ions; it is theresult of the chemical reaction with water. Acids ionize in water, producinghydronium ions and anions. HCl(g) + H2O(l)  H3O+(aq) + Cl-(aq) H3PO4(aq) + H2O(l) H3O+(aq) +H2PO4-(aq) Weak bases ionize in water, producinghydroxide ions and cations. NH3(aq) + H2O(l) OH-(aq) +NH4+(aq)Copyright 2011 John Wiley & Sons, Inc15-22→→→→
    23. Your Turn!Which will dissociate when placed inwater?a. CH3OHb. HClc. KBrd. HClO4Copyright 2011 John Wiley & Sons, Inc15-23
    24. Your Turn! A solution is tested with the conductivityapparatus and the light bulb did not light.Which of the following is not likely?a. The beaker contained only water.b. The beaker contained water andC6H12O6.c. The beaker contained water and CaCl2.d. All of the above are likely possibilities.Copyright 2011 John Wiley & Sons, Inc15-24
    25. Strong and WeakElectrolytes Strong electrolytes areessentially 100% ionized inwater (HCl). Weak electrolytes are muchless ionized (HC2H3O2).Copyright 2011 John Wiley & Sons, Inc15-25
    26. Strong and WeakElectrolytes Use double arrows to indicate weakionization. HC2H3O2(aq) + H2O(l) H3O+(aq) +C2H3O2-(aq) HF(aq) + H2O(l) H3O+(aq) + F-(aq)Copyright 2011 John Wiley & Sons, Inc15-26→→→→
    27. Salts Salts dissociate into at least 2 ions. A 1M solution of NaCl produces a 2Msolution of ions. NaCl(s)  Na+(aq) + Cl-(aq) 1 mole 1 mole + 1 mole A 1M solution of CaCl2 produces a 3Msolution of ions. CaCl2(s)  Ca2+(aq) + 2Cl-(aq) 1 mole 1 mole + 2 moleCopyright 2011 John Wiley & Sons, Inc15-27
    28. Your Turn!What is the concentration of chloride ion ina 2.0 M solution of calcium chloride?a. 1.0 Mb. 2.0 Mc. 3.0 Md. 4.0 MCopyright 2011 John Wiley & Sons, Inc15-28
    29. Colligative Properties ofElectrolyte Solutions Colligative properties depend on themoles of dissolved particles so you haveto take that into account when youcompute freezing point depressions andboiling point elevations. What is the boiling point elevation of a 1.5m aqueous solution of calcium chloride?(The boiling point elevation constant forwater is 0.512 °C/m.)Copyright 2011 John Wiley & Sons, Inc15-29b23 mol ions 0.512°CΔt = 1.5m× × = 2.3°C1 mol CaCl m
    30. Your Turn!What is the boiling point of a 2.0 m aqueoussolution of sodium chloride? (The boilingpoint elevation constant for water is 0.512°C/m.)a. 101.02 °Cb. 1.02 °Cc. 2.05 °Cd. 102.05 °CCopyright 2011 John Wiley & Sons, Inc15-30
    31. Ionization of WaterPure water auto-ionizesH2O(l) + H2O(l) H3O+(aq) + OH-(aq) Concentration H3O+ = Concentration OH-= 1 10-7 M [H3O+] [OH-] = 10-14 In acid solutions, [H3O+]>[OH-] In basic solution, [H3O+]<[OH-]Copyright 2011 John Wiley & Sons, Inc15-31→→
    32. Introduction to pH pH = -log[H+] In pure water, [H+] = 1 10-7 M so pH = -log(10-7) = 7Copyright 2011 John Wiley & Sons, Inc15-32high H+low OH-low H+high OH-
    33. pHCopyright 2011 John Wiley & Sons, Inc15-33
    34. Your Turn! How many times more acidic is a solutionwith a pH of 3 than a solution with a pH of5?a. 2b. 20c. 200d. 100Copyright 2011 John Wiley & Sons, Inc15-34
    35. Introduction to pH pH = -log[H+]Copyright 2011 John Wiley & Sons, Inc15-35
    36. Introduction to pH Calculate the pH of a 0.015M H+ solution. pH = - log (0.015) = 1.82 Note: The digits to the left of the decimalplace in the pH (the characteristic of thelog) reflect the power of ten in the [H+]. Inthis case, the 1. The characteristic is NOTone of the significant figures in the pH. The number of decimal places for themantissa of a log must equal the numberof significant figures in the originalnumber.Copyright 2011 John Wiley & Sons, Inc15-36
    37. Your Turn!What is the pH of a 0.020 M hydrochloricacid solution?a. 0.020b. -2.0c. 1.70d. 1.7e. -1.7Copyright 2011 John Wiley & Sons, Inc15-37
    38. Your Turn! What is the pH of a solution of sodiumhydroxide that has a hydronium ionconcentration of 2.5 10-11?a. 11b. 10.6c. -10.60d. 10.60Copyright 2011 John Wiley & Sons, Inc15-38
    39. Neutralization Neutralization: acid + base  salt + water HCl(aq) + NaOH(aq) H2O(l) + NaCl(aq) Total Ionic Equation: [H+(aq)+Cl-(aq) ]+[Na+(aq) +OH-(aq)] H2O(l) + Na+(aq)+Cl-(aq) Remove spectator ions (Na+ and Cl-) Net Ionic Equation: H+(aq) + OH-(aq)  H2O(l) The driving force for the reaction is the reactionbetween the hydronium ion and the hydroxide ion toform water.Copyright 2011 John Wiley & Sons, Inc15-39
    40. Titration A titration measures the volume of onereagent required to react with a measuredmass or volume of another reagent. A titration is used to determine the amountof acid or base present in a sample. An indicator is used to signal theendpoint, when stoichiometric amounts ofacid and base are present. A buret is used to deliver the titrant into anErlenmeyer flask.Copyright 2011 John Wiley & Sons, Inc15-40
    41.  An acid-base titration is a procedure fordetermining the concentration of an acid(or a base) in a solution by measuring thevolume of base (or acid) of a knownconcentration that completely reacts withit. The solution of accurately knownconcentration is called the standardsolution (titrant), it contains a definitenumber of gram-equivalents per liter.Standard solution is usually added from agraduated vessel called a burette.Copyright 2011 John Wiley & Sons, Inc15-41
    42.  The process of adding titrant until thereaction just complete is termed atitration and the substance to bedetermined is titrated (analyte) The point at which the reaction iscomplete is called the equivalence pointor the theoretical (or stoichiometric) endpoint. This point must be detectable by somechange unmistakable to the eye and thiscan be done by adding an auxiliaryreagent, known as an indicator whichCopyright 2011 John Wiley & Sons, Inc15-42
    43. In order to perform a titrationprocedure a reaction mustfulfill the following condition It must be simple reaction, which can beexpressed by a chemical reaction. Thesubstance to be determined should reactcompletely with the titrant instoichiometric or equivalent proportions. The reaction should be practicallyinstantaneous or proceed with very greatspeed. There must be a marked change in somephysical or chemical property (as colorchange) of the solution at theequivalence point.Copyright 2011 John Wiley & Sons, Inc15-43
    44. Cont An indicator should be available which,by a change in physical properties(Color), should sharply define the endpoint of the reaction. If no visible indicator is available for thedetection of the equivalence point, thelatter can often be determined by othermethod as potentiometer or conductmetric or spectrophotometer titration.Copyright 2011 John Wiley & Sons, Inc15-44
    45.  Titration can be used for many types ofreactions: Neutralization (reaction of acid with base.). Precipitation reaction. Oxidation – reduction reactions Complex formation reactions.Copyright 2011 John Wiley & Sons, Inc15-45
    46. The end point of the titration can be determined by graphic methods1. By using a titration curve – a plot of the pH versus added volume ofNaOH(aq). As in this figure.pHadded volume of NaOHapproximately here is the end pointThe end point of the titration is in the middle of the largest change of the pH.Copyright 2011 John Wiley & Sons, Inc15-46
    47. Titration Experiment http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/acid_base.htmlCopyright 2011 John Wiley & Sons, Inc15-47
    48. Titration If 22.59 mL of 0.1096 M HCl is used to titrate 25.00 mLof NaOH to a phenolphthalein endpoint, what is themolarity of the NaOH? HCl(aq) + NaOH(aq)H2O(l) + NaCl(aq)Copyright 2011 John Wiley & Sons, Inc15-48KnownsCalculateSolving for22.59 mL 0.01096M HCl25.00 mL NaOH base molarity0.1096 mol HCl22.59 mL ×1000 mL soln1 mol NaOH×1 mol HCl= 0.002476 mol NaOH0.002476 mol NaOH0.02500 L soln0.09903 M NaOH
    49. Titration What is the molarity of a sodium hydroxide solution if21.93 mL of NaOH is required to titrate 0.243 g oxalicacid, H2C2O4? H2C2O4(aq) + 2NaOH(aq)  Na2C2O4(aq) + 2H2O(l)Copyright 2011 John Wiley & Sons, Inc15-490.243 g2 2 41 mol H C O×90.04 g 2 2 42 mol NaOH×1 mol H C O0.005398 mol NaOH0.005398 mol NaOH0.02193 L soln= 0.246 M NaOHKnownsCalculateSolving for0.243 g H2C2O421.93 mL NaOH base molarity
    50. Your Turn! What is the concentration of a HNO3solution if 10.0 mL of the solution isneutralized by 3.6 mL of a 0.20M NaOHsolution?a. 0.072 Mb. 53.6 Mc. 0.56 Md. 5.6 MCopyright 2011 John Wiley & Sons, Inc15-50
    51. Writing Net Ionic Equations1. Strong electrolytes in solution are writtenin their ionic form. NaOH(aq) is writtenNa+(aq) +OH-(aq)2. Weak electrolytes and nonelectrolytesare written in their molecular form. H2O(l), HC2H3O2(aq)3. Solids and gases are written in theirmolecular form.4. The net ionic equation does not includespectator ions.5. Equations must be balanced, both inCopyright 2011 John Wiley & Sons, Inc15-51
    52. Net Ionic Equation Formula Equation BaCl2(aq) + Na2SO4(aq) BaSO4(s) + 2NaCl(aq) Total Ionic Equation (Ba2+(aq)+ 2Cl-(aq)) + (2Na+(aq)+ SO42-(aq) )  BaSO4(s) + 2Na+(aq)+2Cl-(aq) Net Ionic Equation Ba2+(aq)+ SO42-(aq)  BaSO4(s)Copyright 2011 John Wiley & Sons, Inc15-52
    53. Net Ionic Equation Formula Equation Na2CO3(aq) + 2HCl(aq)  2NaCl(aq) + CO2(g) + H2O(l) Total Ionic Equation (2Na+(aq)+ CO32-(aq)) + (2H+(aq)+2Cl-(aq) )  2Na+(aq)+2Cl-(aq) + CO2(g) +H2O(l) Net Ionic Equation CO32-(aq) + 2H+(aq)  CO2(g) + H2O(l)Copyright 2011 John Wiley & Sons, Inc15-53
    54. Your Turn! What is the net ionic equation whenhydrobromic acid reacts with potassiumhydroxide?a. H + + OH - HOHb. H + + Br- HBrc. K + + OH - KOHd. K + + H- KHCopyright 2011 John Wiley & Sons, Inc15-54
    55. Acid Rain Acid rain is defined as atmosphericprecipitation that is more acidic thanusual. The general process for the formation ofacid rain:1. emission of nitrogen and sulfur oxidesinto the air2. transportation of these oxidesthroughout the atmosphere3. chemical reactions between the oxidesand water, forming sulfuric acid andCopyright 2011 John Wiley & Sons, Inc15-55
    56. Colloids Solution – Clear homogeneous mixture Suspension – Cloudy heterogeneousmixture with solute particles that can beseparated by filtration Colloid – A mixture in which the dispersedparticles are larger than the solute ions ormolecules of a true solution and smallerthan the particles of a suspension. Colloids can’t be separated byfiltration, and often appear to be cloudy.Copyright 2011 John Wiley & Sons, Inc15-56
    57. ColloidsCopyright 2011 John Wiley & Sons, Inc15-57
    58. Properties of Colloids Brownian Motion – erratic motion ofcolloidal particles caused by thebombardment of solvent molecules. Tyndall Effect – scattering of light bycolloidal particles.Copyright 2011 John Wiley & Sons, Inc15-58
    59. Application of ColloidalProperties Activated charcoal has a very largesurface area. It can be used in gas masksto adsorb poisonous gases which stick tothe surface of the charcoal. Colloidal particles become chargedwhen they adsorb ions on their surface.The Cotrell process uses high voltagecharged plates to clean colloidal dustand smoke particles from air. Dialysis is the process by which dissolvedsolutes can be removed from colloidaldispersions through a semi permeableCopyright 2011 John Wiley & Sons, Inc15-59

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