Chapter 15 Acids and Bases Part I Georgia Gwinnett College Chem 1212K Fall 2013 B Shepler Chapter 15 1 Acid and Base Definitions 1 Arrhenius Acids and Bases 1880 s Acid a substance that produces H ions in aqueous solution Example HCl Base a substance that produces OH ions in aqueous solution Example NaOH 2 Br nsted Lowry Acids and Bases 1923 Acids donate H Example HCl Bases accept H Example NH3 Amphoteric Can act as an acid or a base Example H2O Arrhenius 1903 Nobel Prize 2 Conjugate Acid Base Pairs The concept of conjugate acid base pairs is very important to the Bronsted Lowry theory These are pairs of species that differ only in the presence or absence of a proton H2S aq NH3 aq NH4 aq HS aq In an Acid Base reaction A base accepts a proton and becomes a conjugate acid An acid donates a proton and becomes a conjugate base 3 CH3CO2H H 2O H 3 O CH3CO2 4 Acid Equilibrium HA aq H2O l H3O aq A aq HA generic acid Competition between two bases H3O and HA If HA is a much stronger acid than H3O the equilibrium lies far to the right If H3O is a much stronger acid than HA the equilibrium lies far to the left Ka is Acid Dissociation constant 5 Acid Strength Acid Strength graphical representation of the behavior of acids of different strengths in aqueous solution A strong acid equilibrium lies far to the right HA H2O H3O A A weak acid equilibrium lies far to the left HA H2O H3O A A weak acid yields a relatively strong conjugate base 6 Strong Acids and Bases 7 Strong Acids HCl HBr HI HClO4 HClO3 H2SO4 HNO3 ThePeriodic Table of the Elements 8 Strong Bases LiOH NaOH KOH Ca OH 2 RbOH CsOH Sr OH 2 Ba OH 2 1 2 H He Hydrogen Helium 1 00794 4 003 3 4 5 6 7 8 9 10 Li Be B C N O F Ne Oxygen Fluorine Lithium Beryllium Boron Carbon Nitrogen 6 941 9 012182 10 811 12 0107 14 00674 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar Sodium Magnesium Aluminum Silicon Phosphorus Sulfur Chlorine Argon 22 989770 24 3050 26 981538 28 0855 30 973761 32 066 35 4527 39 948 19 25 26 27 28 29 30 Calcium Scandium Titanium Vanadium Chromium Manganese Mn Fe Co Cobalt Nickel Ni Cu Zn Zinc Gallium Germanium Arsenic Selenium Bromine Krypton 39 0983 40 078 44 955910 47 867 50 9415 51 9961 54 938049 55 845 58 933200 58 6934 63 546 65 39 69 723 72 61 74 92160 78 96 79 904 83 80 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Ca 21 Sc 22 Ti 23 V 24 Cr Iron Copper 31 Ga 32 Ge 33 As 34 Se 35 Neon 20 1797 Potassium K 20 15 9994 18 9984032 Br 36 Kr Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon 85 4678 87 62 88 90585 91 224 92 90638 95 94 98 101 07 102 90550 106 42 107 8682 112 411 114 818 118 710 121 760 127 60 126 90447 131 29 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Cesium Barium Lanthanum Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury Thallium Lead Bismuth Polonium Astatine Radon 132 90545 137 327 138 9055 178 49 180 9479 183 84 186 207 190 23 192 217 195 078 196 96655 200 59 204 3833 207 2 208 98038 209 210 222 87 88 89 104 105 106 107 108 109 110 111 112 113 114 269 272 277 Fr Ra Ac Rf Db Sg Bh Hs Mt Francium Radium Actinium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium 223 226 227 261 262 263 262 265 266 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium 140 116 140 90765 144 24 145 150 36 151 964 157 25 158 92534 162 50 164 93032 167 26 168 93421 173 04 174 967 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium 237 244 243 247 247 251 252 257 258 259 262 232 0381 231 03588 238 0289 1995 IUPAC masses and Approved Names from http www chem qmw ac uk iupac AtWt masses for 107 111 from C EN March 13 1995 p 35 112 from http www gsi de z112e html Chapter 15 7 Ka and Acid Strength HA H2O H3O A 8 Ion product constant Autoionization of water H2O l H2O l H3O aq OH aq Kw H3O OH Kw 1 0 x 10 14 at 25oC Kw is ion product constant 9 pH and the p function p function is just an algebraic function The p function is a useful means of expression the concentration of proton and hydroxide ion pH log H pOH log OH Since Ka and Kb values are so small the p function allows them to be expressed more neatly pKa log Ka pKb log Kb 10 pH Scale pH log10 H3O pH 7 basic solution H3O OH pH 7 neutral solution H3O OH pH 7 acidic solution H3O OH 11 pH and pOH H3O or OH can be calculated from the pH or the pOH Another useful relationship pH pOH 14 00 It comes from the equilibrium constant for the autoionization of water called the ion product constant for water Kw log K w H 3O OH 1 0 x10 14 14 00 pH pOH Lets make a list of all the useful equations 12 Example What are H3O OH and pOH in a solution with a pH of 4 77 Chapter 15 13 Calculate the pH of a Strong Acid Solution Strong acids COMPLETELY dissociate The dissociation goes to completion all reactants are converted to products The H3O is the same as the initial concentration of the acid What is the H OH pH and pOH of a 0 055 M solution of HCl Chapter 15 14 Calculate the pH of a Weak Acid Solution Weak acids do NOT dissociate completely At equilibrium we have significant amounts of reactant Undissociated Acid HA present in the solution Calculating the pH is just an ICE table problem Hypochlorous Acid HClO has a pKa of 7 54 What are the H3O pH ClO and HClO in 0 115 M HClO Chapter …
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