Acid-Base Pairs H2O + NH3  OH- + NH4+ acid base base acid H2O/OH- are an acid-base pair hydroxide ion is the conjugate base of water NH4+/NH3 are an acid-base pair ammonium ion is the conjugate acid of ammonia

HClO 4 + H2O  H3O+ + ClO4- acid: HClO4 conjugate base: ClO4- HClO4/ClO4- are an acid-base pair base: H2O conjugate acid: H3O+ H3O+/H2O are an acid-base pair _________________________________________________________ H2O + H2O  H3O+ + OH- acid: H2O conjugate base: OH- H2O/OH- are an acid-base pair

conjugate acid-base pairs acid: HCl conjugate base of HCl: Cl- acid: H2SO4 conjugate base of H2SO4: HSO4- acid: NH3 conjugate base of NH3: NH2- ____________________________________________________________________________________ base: NH3 conjugate acid of NH3: NH4+ base SO42- conjugate acid of SO42-: HSO4-

The stronger the acid, the weaker is it’s conjugate base The weaker the acid, the stronger is it’s conjugate base The stronger the base, the weaker is it’s conjugate acid The weaker the base, the stronger is it’s conjugate acid Strong acid HI > HBr > HCl >> HF Weak acid Strong Base F- >> Cl- > Br - > I- Weak Base Acid strength depends on bond strength & stability of the resulting anion: HF  H+ + F - Table 10-2

Ternary Acids Ternary Acid - An acid that contains hydrogen, oxygen and a non-metal most ternary acids are hydroxyl compounds of nonmetals (oxoacids): HNO3 can also be written as HONO2 H2SO4 can also be written as (OH)2SO2 .. .. O || N .. .. O O H .. .. .. hydroxyl groups hydroxyl group

Acid Strength of Ternary Acids HNO3  H+ + NO3- Why does nitric acid lose a proton instead of a hydroxide ion? The E.N. = 0.5 (N & O) and 1.4 (O & H) Why is HNO3 a strong acid and HNO2 (HONO) a weak acid? look at the ox. # Nitric Acid N +5 ox. state Nitrous Acid N +3 ox. state .. .. O || N 3.0 3.0 .. N 3.5 3.5 .. 2.1 .. 2.1 .. O O H .. .. .. O O .. .. .. H hydroxyl group hydroxyl group

Acid Stregth of HClOx series x= 1, 2, 3 or 4 hypochlorous, chlorous, chloric and perchloric acid HClO HClO2 HClO3 HClO4 +1 +3 +5 +7 HClO4 >> HClO3 > HClO2 > HClO What does this tell us about their conjugate bases? ClO4- << ClO3- < ClO2- < ClO -

Make a hypothesis on the acid strength of HBrO3 compared to HIO3 Br and I are in the same oxidation state (+5) The ternary acid with the most electronegative non-metal will be the most acidic HBrO3 > HIO3

Acidic Salts & Basic Salts Normal Salt - A salt that doesn’t have ionizable hydrogens or hydroxyl groups. Acidic Salt - A salt that has ionizable hydrogens but, doesn’t necesarily produce acidic solutions. H2CO3 + NaOH  NaHCO3 + H2O H2CO3 + OH-  HCO3- + H2O Polyprotic Acid rxn w/ < stoich. amount of SB gives an acidic salt

Fe(OH)2(s) + HCl  Fe(OH)Cl(s) + H2O Basic Salt - A salt that has basic hydroxyl groups but doesn’t necesarily create basic solutions. Fe(OH)2(s) + HCl  Fe(OH)Cl(s) + H2O Fe(OH)2(s) + H+ + Cl-  Fe(OH)Cl(s) + H2O polyhydroxy base rxn w/ < stoich. amount of SA gives a basic salt

Preparation of Acids Binary Acids - hydrogen halides nonvolatile + salt of  salt of + volatile acid volatile acid nonvolatile acid acid H2SO4 + NaF(s)  NaHSO4 + HF(g) H3PO4 + NaBr(s)  NaH2PO4 + HBr(g) Ternary Acids nonmetal oxide + water  ternary acid N2O5(s) + H2O  2HNO3 Binary & Ternary Acids PX3 + 3H2O  H3PO3 + 3HX PX5 + 4H2O  H3PO4 + 5HX