Princ of Chemistry II
Princ of Chemistry II CHEM 1212K
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This 43 page Class Notes was uploaded by Jeff Gleichner on Tuesday October 27, 2015. The Class Notes belongs to CHEM 1212K at University of West Georgia taught by David Boatright in Fall. Since its upload, it has received 9 views. For similar materials see /class/230254/chem-1212k-university-of-west-georgia in Chemistry at University of West Georgia.
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Date Created: 10/27/15
Chapter 14 Aqueous Equilibria Acids and Bases AcidBase Concepts The BronstedLowry Theory Arrhenius Acid A substance that dissociates in water to produce hydrogen ions H1 HAaq H1aq A139aq Arrhenius Base A substance that dissociates in water to produce hydroxide ions 0H1 MOHaq M1aq OH139aq Copyright Milli earson Prentice Ha i lino Chapter 142 AcidBase Concepts The BronstedLowry Theory BronstedLowry Acid A substance that can transfer hydrogen ions H In other words a proton donor BronstedLowry Base A substance that can accept hydrogen ions H In other words a proton acceptor HA B BH A H donor H acceptor H donor H acceptor Acid Base Acid Base Conjugate acid base pairs Copyright 2010 Pearson Prentice Hall Inc Conjugate AcidBase Pairs Chemical species whose formulas differ only by one hydrogen ion H Chapter 143 AcidBase Concepts The BronstedLowry Theory AcidDissociation Equilibrium R w p n o I g v w H H l l H A H Qz 1 H l3 A H HAaq H200 H3Oaq Aaq Acid Base Acid Base Copyright 2010 Pearson Prentice Hall Inc Conjugate acid base pairs AcidBase Concepts The BranstedLowry Theory BaseDissociation Equilibrium I K 1 1 A39x Va V Ks R X V H H H H 1lii O H 0 H H IlI H H H NH3aq H200 V OH aq NH 1151 Base Acid Base Acid Conjugate acid base pairs Copyright 2010 Pearson Prentice Hall Inc Chapter 145 Which of the following pairs of species are conjugate pairs A H3PO4 and P043 B NH4 and NH239 C CH and H20 D HCI and H30 Acid Strength and Base Strength HAaq H200 x H301aq A139aq Acid Base Acid Base With equal concentrations of reactants and products what will be the direction of reaction Stronger acid Stronger base Weaker acid Weaker base Eopwgrrigi nt 5 MIKE Pearson Prentice Haii Linc Chapter 14j 7 Acid Strength and Base Strength Weak Acid An acid that is only partially dissociated in water and is thus a weak electrolyte Concentration before Equilibrium concentrations dissociation after dissociation HA H3O A The extent of Strong acid 400 dissociation is d nearly 100 for lssocmhon a strong acid HA HA HA Weak acid Pal hair The extent of HSO A dissociation is i considerably less than 100 for a weak acidv dissociation HA O dissociation Copyright 2010 Pearson Prentice Hall Inc Very weak acid The extent of 317 dissociation is 39139 39l39quotquot39 nearly 0 fora very weak acidi E Chapter 148 TABLE 141 Relative Strengths of Conjugate Acid Base Pairs Acid HA Base A Stronger HClO4 Strong acids ClOf Very weak bases Weaker acid HCl 100 dissociated Cl Negligible tendency base H2804 in aqueous H504 to be protonated in HNOs solution NO3 aqueous solution H30 H20 HSO4 8042 H3PO4 1121304 HNOZ NOZ HF Weak acids F Weak bases CH3COZH Exist in solution CH3C02 Moderate tendency HZCO3 as a mixture of HCO3 to be protonated in HZS HA A and H3O HS aqueous solution NHL NH3 HCN CN HCO339 C032 HZO OH NH3 Very weak acids NHZ Strong bases Weaker OH Negligible tendency 02 100 protonated in stronger acid Hz to dissociate H aqueous solution base Copyright 2010 Pearson Prentice Hall Inc Chapter 149 Dissociation of Water Autoionization of water water is amphoteric can act as an acid or base O H O H H O H O H l quot H H H Acid Base Acid Base Conjugate acid base pairs Copyright 2010 Pearson Prentice Hall Inc Dissociation of Water 2H20I H301aq OH139aq IonProduct Constant for Water KW H301OH139 at 25 C H3011 OH139 10 x10397 M Kw 10 X 103971O X1O39710 x1044 Dissociation of Water KW H3O1OH139 10 x 1014 KW 10 x103914 1 H30 ow1 ow1 OW KW 10 x103914 H3011 39 H3011 Cmmrrigi ni t Z Paargm Pwem ica Haii Emu Chapter 1411 Concentration Dissociation of Water gt 10 x 10 7 M H304 OH H30 0H 10 X 10 7 M OH I I H30 lt 10 X 10 7 M I I Acidic Neutral Basic solution solution solution Copyright 2010 Pearson Prentice Hall Inc Chapter 1412 The pH Scale 3130 p3 1014 147610 M NaOH 1013 13 l 39 10 12 12 7 4 Household 1 1 pH 1011 Hi ammonia 10 lt Milk of 10 10 10 magnesia 109 9 39 108 8f Bakmg soda Human blood gt 10 7 7T Pure water lt Milk Basic Neutral Basic solution pH gt 7 Blackcoffee Neutral solution pH 7 Acidic Acidic solution pH lt 7 Wine quot Vinegar colas Lemon juice Stomach acid 10 M HCl Copyright 2010 Pearson Prentice Hall Inc Chapter 1413 The pH Scale The hydronium ion concentration for lemon juice is approximately 00025 What is the pH when H3011 00025 M 2 significant figures then 2 decimal places Copyright 2010 i eareon Hematite Hail Eric Chapter 1414 The pH Scale Calculate the pH of an aqueous ammonia solution that has an OH139 concentration of 00019 M Copyr g tt 2010 Pearson Wenttce Haw inc Chapter 1415 The pH Scale Acid rain is a matter of serious concern because most species of fish die in waters having a pH lower than 45 50 Calculate H301 in a lake that has a pH of45 lemrr g nt Z Pearsmm PLWEWHEE Hall Emu Chapter 1416 Measuring pH AcidBase Indicator A substance that changes color in a specific pH range Indicators exhibit pHdependent color changes because they are weak acids and have different colors in their acid HIn and conjugate base In139 forms HInaq H20I H3O1aq In139aq ColorA Color B Copyright Zt i Pearson Prentice Haii ENC Chapter 14117 Indicator Methyl violet Thyme blue Melhyl orange Bromcresol green Methyl red Chlorphenol red Bromthymol blue Phenol red Phenolphthalein Thymolphthalein Allzarin yellow Measuring pH PEI I I I I I I I I I I I I I U 1 2 3 4 5 6 7 8 9 10 11 12 Yellow Violet Red Yellow acid range Yellow i Blue base range Red Yelloworange Yellow 3 Blue Red Yellow Yellow Red Yellow Blue Yellow Red Colorless 3 Red Colorless Blue Yellow 1 Violet Copyright 2010 Pearson Prentice Hall Inc Chapter 1418 The pH in Solutions of Strong Acids and Strong Bases What is the pH of a 0025 M solution of HNOg 0 1 o HNOsaQ H200 39 H301aQ N03139aQ Since HNO3 is a strong acid H3O1 HNO3 Comrrigm Zt l i aarsom Pi e i Haii lino Chaptm 14419 The pH in Solutions of Strong Acids and Strong Bases What is the pH of a 0025 M solution of NaOH NaOHaq Na1aq OH139aq Since NaOH is a strong base OH139 NaOH Comrrigm Zt l i aarsom Pi e i Haii lino Chaptm 1420 Equilibria in Solutions of Weak Acids HAaq H200 H301aq A139aq H301A139 AcidDissociation Constant Ka HA Comrr g tt Zt l Paargon Menace HEW inc Chaptm 1421 TABLE 142 Acid Dissociation Constants at 25 C Molecular Acid ormula Structural Formula Ka pKaf Stronger Hydrochluric HCI Hi 2 X 10 763 acid Nitrous HNO2 HONO 45 x 104 335 Hydro uon39c HF Hv F 35 X 10quot 346 Acetylsalicylic Csto4 0 CH3 30 x 104 352 aspirin I C H C O C C OH H kc I H O 0 Formic HCOgl l H C 0 7 H 18 x 104 374 0 HO c C scnrbic CEHSOi H O 80 x 10 410 vitamin c C C HO H IH CHZOH OH H H C C Benzoic CEHSCOZH H C C C 65 x 10 419 C 0i i H H 0 Acetic CIlgCOZII CH3 7 C 70 18 X 10 5 474 Hypucl omus HOCl H O Cl 35 X 10quot 746 weaker Hydmcyanic HCN H C EN 49 x 10 I 931 acid Methanol CIIJOlI CH3OH 29 x 10 quot 1554 The pmtuii that is transferred to water when the acid dissuciales is sl iuwn in red era lug K8 Copyright 2010 Pearson Prentice Hall Inc Equilibria in Solutions of Weak Acids The pH of 0250 M HF is 2036 What are the values of Ka and pKa for hydrofluoric acid HFaq H200 H301aq F139aq Cmmrrigi nit Z i aarsmm Pragmatics Haii TERM Chapter 1423 Calculating Equilibrium Concentrations for Weak Acids Calculate the pH of a 010 M HCN solution At 25 C Ka 14 x109 HCNaq H200 H301aq CN139aq Cmmrrigm Zt l i aargmn Pl eli39i ill Hail line Chaptm 1424 Percent Dissociation in Solutions of Weak Acids HA dissociated Percent dissociation x 100 HA initial Use numbers from previous problems Polyprotic Acids H2003aQ H200 H301aQ HCOs139aQ H301 H003139 a1 X 107 H2003 HCO3139aq H20I H301aq 003239aq H301 003239 82 56 X 103911 H003139 Cmmrr g ni t Z Paargm a Manama Han Emu Chapter 1426 Polyprotic Acids TABLE 143 Stepwise Dissociation Constants for Polyprotic Acids at 25 C Name Formula K31 K32 Ka3 Carbonic acid HZCO3 43 X 10 7 56 X 10 11 Hydrogen sulfide HZS 10 X 10 7 10 19 Oxalic acid H2C204 59 x 10 2 64 x 10 5 Phosphoric acid H3PO4 75 x 103 62 x 10 8 48 x 10 13 Sulfuric acid H2804 Very large 12 x 10 2 Sulfurous acid H2503 15 X 10 2 63 X 10 8 Because of its very small size Kaz for H28 is difficult to measure and its value is uncertain Copyright 2010 Pearson Prentice Hall Inc Chapter 1427 Equilibria in Solutions of Weak Bases Baq H200 BH1aq OH139aq Base Acid Acid Base BH1OH139 BaseDissociation Constant Kb T NH3aq H200 NH41aq OH139aq NH4110H11 Kb NH31 Eo zvvgrr g nt 9 mm Paargon Menace Hana Emu Chapter 14428 Equilibria in Solutions of Weak Bases TABLE 144 Kb Values for Some Weak Bases and Ka Values for Their Conjugate Acids at 25 C Base Formula B K Conjugate Acid BH Ka Ammonia NH3 18 x 10 5 NH4 56 x 10 10 Aniline C6H5NH2 43 x 1010 C6H5NH3 23 x 1015 Dimethylamjne CH32NH 54 x 104 CH32NH2 19 x 1011 Hydrazine N2H4 89 x 10 7 N2H5 11 x 108 Hydroxylamjne NHZOH 91 x 109 NH3OH 11 x 106 Methylamine CH3NH2 37 x 101 1 CH3NH3 27 x 10 11 Copyright 2010 Pearson Prentice Hall Inc Chapter 1429 Equilibria in Solutions of Weak Bases Calculate the pH of a 040 M NH3 solution At 25 C Kb 18 x1O5 NH3aq H200 NH41aq OH139aq Cmmrr gm Zt l Paargmm Pmm ca HEW Emu Chaptm 1430 Relation Between Ka and Kb gxmm W J conjugate acidbase pair Kw Kw amp Kb Ka pKa pr pKW 1400 lemrr g ni t Z Pearem a Meantime Han Emu Chapter 1431 AcidBase Properties of Salts Salts That Yield Neutral Solutions The following ions do not react appreciably with water to produce either H301 or CH ions Cations from strong bases Alkali metal cations ofgroup 1a Li1 Na K Alkaline earth metal cations of group 2a Mg2 Ca2 Sr2 Ba2 except for Be2 Anions from strong monoprotic acids Cl Br 1139 N031 and CIO4139 Coimrr gi nt Milli earson Prentice Hall lino Chapter 1432 AcidBase Properties of Salts Salts That Yield Acidic Solutions Salts such as NH4C that are derived from a weak base NH3 and a strong acid HCI yield acidic solutions NH41aQ H200 H301ltaqgt NHsltaqgt Ammonium ion NH41 is the conjugate acid of the weak base ammonia NH3 while chloride ion Cli39 is neither acidic nor basic Copyright Milli earsm l Prentice Hall lino Chapter 1433 AcidBase Properties of Salts Salts That Yield Acidic Solutions Hydrated cations of small highly charged metal ions such as Al3 Electrons are attracted toward AI Q 8 thus weakening the 0H bonds 2 39V L This OH bond breaks and 1 god H is transferred to H20 l w x l quot b y 1 t ll W A1H20e3 q H200 A11L1205OH2 0117 Copyright 2010 Pearson Prentice Hall Inc Chapter 1434 AcidBase Properties of Salts Salts That Yield Basic Solutions Salts such as NaCN that are derived from a strong base NaOH and a weak acid HCN yield basic solutions CN139aq H200 HCNaq OH139aq Cyanide ion CN139 is the conjugate base of the weak acid hydrocyanic acid HCN while sodium ion Na1 is neither acidic nor basic Copyright Milli earson Prentice Hall lino Chapter 1435 AcidBase Properties of Salts Salts That Contain Acidic Cations and Basic Anions The pH of an ammonium carbonate solution NH4ZCO3 depends on the relative acid strength of the cation and the relative base strength of the anion Is it acidic or basic Cmpyright 20m Pearsbn Pren tce Haii Linc Chapter 1436 AcidBase Properties of Salts Salts That Contain Acidic Cations and Basic Anions NH42COg NH41aq H200 H301aq NH3aq Ka 003239aq H200 HCOsl39aq OH139aq Kb Three possibilities Ka gt Kb The solution will contain an excess of H3O1 ions pH lt 7 Ka lt Kb The solution will contain an excess of OH ions pH gt 7 Ka z Kb The solution will contain approximately equal concentrations of H301 and OH ions pH 7 Coimrr gi nt 2am earson Pi39en tice Halli lino Chapter 1437 AcidBase Properties of Salts Salts That Contain Acidic Cations and Basic Anions NH42003 NH41aq H200 H301aq NH3aq Ka 003239aq H20I HCO3139aq OH139aq Kb K 10X103914 Ka for NH41 W 56 X 1010 Kb for NH3 18x 10395 2 KW 10x 1014 4 KforCO 39 18x1039 b 3 Ka for HCO3139 56 x 1011 Basic Ka lt Kb Empwr gm 9 mm Paargmn Menace Hana Eng Chapter 14438 AcidBase Properties of Salts TABLE 145 Acid Base Properties of Salts Ions That pH of Type of Salt Examples React with Water Solution Cation from strong base NaCl KNO3 None 7 anion from strong acid Balz Cation from weak base NH4C1 NH4NO3 Cation lt7 anion from strong acid CH33NHC1 Small highly Charged cation AlCl3 CrNO33 Hydrated lt7 anion from strong acid FeClO43 cation Cation from strong base NaCN KF Anion gt7 anion from weak acid NazCO3 Cation from weak base NH4CN NH4F Cation and lt7 if Ka gt Kb anion from weak acid NH42C03 anion gt7 if Ka lt Kb 7 if Ka Kb Copyright 2010 Pearson Prentice Hall Inc Predict whether 010 M solutions of the following are acidic basic or nearly neutral a C5H5CNHCI b KF Copyright MCGrawllill 2009 40 Factors That Affect Acid Strength Bond Strength HI HCl HBr Copyright 2010 Pearson Prentice Hall Inc HF ltlt HCl lt HBr lt H1 570 431 366 298 Factors That Affect Acid Strength Bond Polarity CH4 lt NH3 ltlt H20 lt HP 25 30 35 40 Copyright 2010 Pearson Prentice Hall Inc Factors That Affect Acid Strength Oxoacids H O I lt H O Br lt H O Cl Dissociation constant Ka 23 X 10 11 20 X 10 9 35 x 10 8 Electronegativity 25 28 30 El e e fo Copyright 2010 Pearson Prentice Hall Inc Chapter 1443
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