1. Examples of chemical % yield (continued) MW 32 44 44 18 Given excess 2.2 g Mol C 3 H 8 =2.2 =0.050 44 = 4 x 0.05 =0.2 mol 1 Product H 2 O moles theory 5O 2 + C 3 H 8  3CO 2 + 4H 2 O Bob reports making 4.0 g H 2 O from 2.2 g C 3 H 8. Is Bob an idiot or okay ? Bob Reports 4.0 g H 2 O Maximum g H 2 O=18 g/mol*0.2 mol=3.6 g  Bob’s an idiot

2. Moles level 1 Mol-mass-count Moles level 2 Body parts: mole ratios within a compound Balancing % composition/combustion Moles level 3 Reaction stoichiometry Limiting and %yields More practice with ?????

3. We is done with moles !!! Where we are on the mole road trip….

4. And now, after many weeks of &^%!! Moles …. for something completely different…. CLASSICAL REACTIONs

5. SLO #6 Students will be able to: write, balance, identify and predict common reaction classes (metatheses, acid- base, redox). Today’s Student Learning Objective (SLO): Translation: What happens when I add this to that ?

7. What to read… chapter 4 ( + a bit of Ch. 14) Metatheses 153-162 Acid-base 163-170; 653-656 Oxidation-reduction 171-177 CLASSICAL REACTIONs (continued)

8. Classical Reactions 1) Metathesis (double replacement) Pb(NO 3 ) 2 (aq) + 2KI(aq)  PbI 2 (s) + 2KNO 3 (aq) Complete Molecular reaction Pb 2+ + 2I -  PbI 2 (s) Net Ionic Reaction Pb 2+ +2NO 3 - +2K + +2I -  PbI 2 (s) + 2K + +2NO 3 - Complete Ionic Reaction METATHESIS REACTIONS THIS WEEK IN LAB

9. 1)Metathesis (double replacement) –continued General characteristics Ionic, aqueous salts are reactants Product formed from cation swap is a solid Low energy…no appreciable heat in/out Pb 2+ + 2I -  PbI 2 (s) Net ionic CLASSICAL REACTIONs overview (continued)

10. Let,’s practice a few on the board, kids !

11. 2) Acid-base HCl(aq) + NaOH(aq ) NaCl(aq) + HOH + heat acidbase saltwater Complete Molecular reaction H + + OH -  H 2 O Net ionic reaction ` neutralization H + + Cl - + Na + +OH -  Na + + Cl - +H 2 O Complete Ionic reaction CLASSICAL REACTIONs overview (continued)

12. Demo reaction: ID the acid, base and salt below H 2 SO 4 + 2NaOH  Na 2 SO 4 + 2H 2 O Acid Base Sulfuric acid (car battery acid) sodium hydroxide (essence of Lye) sodium sulfate (`Glauber’s Salt =laxative) salt 2H + + SO 4 2- +2Na + + 2OH -  2Na + + SO 4 2- +2H 2 O Complete ionic reaction? Net ionic reaction ? 2H + + 2OH -  2H 2 O Let’s run this one

13. General characteristics Reactants are specially defined `acid’ and `base’ ionic solutions Products are soluble salt and water Significant heat is generated Indicators signal endpts H + + OH -  H 2 O Net ionic reaction 2) Acid-base…- continued CLASSICAL REACTIONs overview (continued)

14. Acid-Base Theories (pp 163-170, 652-655) 0 ) Pre-science: acids and bases are eternal opposites ACID + BASE = `BALANCE’ Positive + negative = null Hot + cold = just right Taoist version CLASSICAL REACTIONs overview (continued)

15. Acid-Base Theories (pp 653-656) Modern Theory: Try #1 Svante Arrhenius: Father of the first modern acid/base theory Young Arrhenius (not considered promising) Old Arrhenius ( wins Nobel prize in 1903 for same acid base theory) Thesis on Acids & Bases derided by his research committee… Graduates with Ph.D ordinare (no distinction) see p. 144 CLASSICAL REACTIONs overview (continued)

16. A measure of this Ph.D `ordinaire’’s brilliance… In 1896 Arrhenius predicted green house gas (CO 2 ) from profligate burning of the the newly popular fuel source … petroleum oil… would cause (gasp !) measurable and catastrophic global warming… … starting in 1990-2000 AD …the entire scientific establishment (and Standard Oil) laughed at him (again) CLASSICAL REACTIONs OVERVIEW(continued)

17. FYI…. Until 2013 not a single current Republican member of the US Congress admitted that global warming is caused by burning of fossil fuels.

18. Oil burning starts here

19. 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)

20. HCl(aq) + NaOH(aq)  NaCl(aq) + H 2 O ACID + BASE = SALT + WATER Acid-Base reactions ala’ Arrhenius: A+B= neutral H 2 SO 4 + Mg(OH) 2  MgSO 4 (aq) + 2H 2 O General rule for Arrhenius acid-base CLASSICAL REACTIONs (continued)

21. 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)

22. 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)

23. 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)

24. Bronsted to the rescue… Young Bronsted…Swedis h 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 a few years after marriage and kids CLASSICAL REACTIONs (continued)

25. 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

26. 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

27. 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 -

28. 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

29. 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

30. 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

31. 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’

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

33. 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.

34. 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 -

35. 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.

36. 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

37. 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