1. Let’s do some acid (and bases), kids !

2. 1)Arrhenius Model HF HCl HBr HNO 3 HClO 4 H 2 SO 4 H 2 CO 3 H 3 PO 4 BASE NaOH KOH NH 4 OH Ca(OH) 2 Mg(OH) 2 Al(OH) 3 Fe(OH) 3 ACID =H + donor =OH - donor CLASSICAL REACTIONs overview(continued)

3. ACID + BASE = SALT + WATER General Arrhenius acid-base reaction: CLASSICAL REACTIONs (continued)

4. The `Inconvenient Truth’ about the Arrhenius model: basic salts EXAMPLE: Na 2 CO 3 (sodium carbonate ) No H + or OH - ….=> salt only CLASSICAL REACTIONs OVERVIEW continued)

5. The `Inconvenient Truth’ about the Arrhenius model: basic salts (continued) Turns pink in presence of phenolphthalein gas-forming reaction with HCl, pink disappears experimental results of adding to water: EXAMPLE: Na 2 CO 3 (sodium carbonate) => A base !!!!????? Where’s OH ??? CLASSICAL REACTIONs OVERVIEW(continued)

6. The `Inconvenient Truth’ about the Arrhenius model: basic salts (continued) Other examples of `basic’ salts Na 3 PO 4 K 2 SiO 3 NaC 2 H 3 O 2 Basic salts cannot be rationalized using Arrhenius’ acid/base model CLASSICAL REACTIONs OVERVIEW (continued)

7. Bronsted to the rescue… Young Bronsted… Swedish chemist circa 1910… Young James Dean…American actor circa 1955 …(“Rebel Without a Cause,”“East of Eden”, “Giant” ) Winner of the Bronsted look alike contest…. Bronsted after marriage and kids CLASSICAL REACTIONs (continued)

8. Bronsted Model of Acids/Bases 3 new concepts (see pp 452-453 & 623-6) Acid= HF, HCl, HBr HNO 3 HClO 4 H 2 SO 4 H 2 CO 3 H 3 PO 4 No real change from Arrhenius proton donor (=H + ) CLASSICAL REACTIONs OVERVIEW(continued) ARRHENIUS ACIDS = BRONSTED ACIDS New Concept # 1: Follow the protons

9. BASE= OH - CO 3 -2,PO 4 -3, C 2 H 3 O 2 -,SiO 3 -2 … proton acceptor CLASSICAL REACTIONs OVERVIEW(continued) BRONSTED’S MODEL OF ACIDS/BASES: New Concept #1: following the protons (cont.) The set of Bronsted bases includes Arrhenius bases + …. … nearly any negative ion (=anion) that even weakly attracts protons Examples of Bronsted Bases

10. How the proton acceptor creates the basic salt effect : CO 3 2- + H-OH.. Bronsted Base is basic in water because it splits water to make OH - ! Hydrolysis reaction CLASSICAL REACTIONs OVERVIEW(continued) BRONSTED’S MODEL OF ACIDS/BASES: New Concept #2 Hydrolysis…Bronsted bases `split’ water !!! EXAMPLE  HCO 3 - + OH -

11. Conjugate idea is like going drag… Men=acid Women=base BASE ACID CONJUGATE ACID CONJUGATE BASE Identify `acids’ and bases BRONSTED’S MODEL OF ACIDS/BASES: New Concept #3a: conjugate acid/base pairs

12. CO 3 2- + H-OH Acid  conjugate base Base  conjugate acid Base Acid Conjugate acid Conjugate base CLASSICAL REACTIONs OVERVIEW(continued) BRONSTED’S MODEL OF ACIDS/BASES: New Concept #3a: conjugate acid/base pairs  HCO 3 - + OH - Identify `acid’ and base Identify conjugate acid and base

13. PO 4 3- + HCO 3 -  HPO 4 2- + CO 3 2- Acid  conjugate base Base  conjugate acid acid base conjugate base conjugate acid new concept #3a: Conjugates (continued) When acid and base reacts…. EXAMPLE: IDENTIFY ACID, BASE AND THEIR CONJUGATE BASE AND ACID ABOVE

14. ACID + BASE  CONJUGATE BASE + CONJUGATE ACID Bronsted Model Contrast to Arrhenius Model ACID + BASE  SALT + WATER CLASSICAL REACTIONs OVERVIEW(continued) BRONSTED’S MODEL OF ACIDS/BASES: New Concept #3b:  spontaneous acid + base reactions produce weaker acids + bases Both products `neutral’

15. ARRHENIUS ACID-BASE THEORIES SUMMARIZED BRONSTED ACID =H + DONOR PROTON DONOR BASE=OH - DONORPROTON DONOR ACID + BASE  SALT + WATER CONJUGATE ACID + CONJUGATE BASE

16. In-Class Practice Iding Pieces of Bronsted Acid- Base reactions Let’s do acid !

17. What observation required Bronsted to create a new Acid/Base Theory different than Arrhenius’s model ? A.Many salts formed conjugate acids. B.Spontaneous acid+base reactions only occurred if weaker acids and bases formed. C.H 2 O spontaneously decomposed to OH- and H+ in presence of various salts. D.Many salts without OH - somehow created OH - in water.

18. Which part of the Bronsted salt K 3 PO 4 is the proton acceptor ? A.K + B.O 2- C.P 3- D.PO 4 3- E.K 3 PO 4 F.OH -

19. What new concept of Bronsted’s most directly explains why many salts are bases? A.The anionic part of salts can hydrolyze water. B.Spontaneous acid/base reactions lead to weaker conjugate acids/bases. C.Bronsted bases are proton acceptors. D.Bronsted acids are proton donors.

20. In-class reaction Jeopardy Low heat, precipitates, cation swap metathesis WHAT IS… Na 2 CO 3 for example A Bronsted base What’s my reaction type: HCl + KOH  KCl + H 2 O Acid/base neutralization (Arrhenius) Pick the Arrhenius acids H 2 O HNO 3 NaHCO 3 HBr NaCl HNO 3 HBr

21. In-class reaction Jeopardy WHAT IS… What’s my reaction type: K 3 PO 4 + H 2 O  HK 2 PO 4 + KOH Acid/base hydrolysis (Bronsted) Write my products ? AgNO 3 (aq) + NaCl(aq)  ? AgCl(s) + NaNO 3 (aq) Pick the Bronsted base(s) NaOH HBr NaHCO 3 K 3 PO 4 NaOH NaHCO 3 K 3 PO 4 Pick the Arrhenius bases NaOH

22. OXIDATION-REDUCTION (REDOX) REACTIONS see pages text 458-466 REDOX REACTIONS ALL INVOLVE CHANGES IN ELECTRON OWNERSHIP EXAMPLE #1 : (w/demo) Mg o + 2H +  Mg 2+ + H 2 0+2 +10 Mg loses 2 e - Each H+ gains 1 e- Losing is oxidation Gaining is reduction

23. Leo-Ger Lose electrons = oxidation Gain electrons =reduction Oxidation-Reduction: Remembering which is which…..

24. Oil-Rig Oxidation is losing Reduction is gaining Oxidation-Reduction: Remembering which is which…..

25. Qualitative Features of REDOX Reactions Often involves gross changes in state (solid  gas or solution) Extreme changes in energy (fire, light, explosions) prime engine of living metabolisms (if you breathe, you redox…)

26. How to know if a reaction is a `redox’ reaction: assign OXIDATION NUMBERS RULES: (SEE PAGE 171 TABLE 4.2) 1) PURE UNCHARGED ELEMENTS HAVE 0 OXIDATION # H 2 O 2 N 2 Fe Cu Au 0 0 0 0 0 0 To emphasize, metals often written M o Example: Fe  Fe o

27. How to know if a reaction is a `redox’ reaction: assign OXIDATION NUMBERS RULES: (SEE PAGE 171 TABLE 4.2) 2) OXIDATION # OF A CHARGED ATOM IS THE CHARGE ITSELF F - Co 3+ H + S 2- +3+1-2

28. How to know if a reaction is a `redox’ reaction: assign OXIDATION NUMBERS RULES: (SEE PAGE 171 TABLE 4.2) 3) F (AND USUALLY THE OTHER HALOGENS) ARE -1 in binary and larger compounds NaFHClNCl 3 SiOF 2 -1 -1 -1 * -1 * * Each atom of Cl or F is -1

29. How to know if a reaction is a `redox’ reaction: assign OXIDATION NUMBERS RULES: (SEE PAGE 171 TABLE 4.2) 4) O IS -2 EXCEPT IN PEROXIDES (X-OO-Y) WHERE IT IS -1 H 2 ONaOHK 2 CrO 4 NaMnO 4 -2-2 -2* -2* * Each atom of O in compound is -2 HOOH =H 2 O 2 -1 -1 PEROXIDE STRUCTURE

30. How to know if a reaction is a `redox’ reaction: assign OXIDATION NUMBERS RULES: (SEE PAGE 171 TABLE 4.2) 5)H IS +1 FOR COVALENT COMPOUNDS (AND MOST IONIC ONES TOO) HClNH 3 H 2 O CH 4 +1 +1* +1* +1* *Each H in the compound is +1

31. PRACTICE ASSIGNING OXIDATION # N2N2 O2O2 H2OH2O Fe 2 O 3 H 2 SO 4 N=0 O=0 H=+1 O= -2 Fe=+3O= -2 H= +1 O= -2 S=+6 Provide oxidation # for all elements below