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Kinetics and Equilibrium

Kinetics and Equilibrium. Kinetics. The study of the mechanisms of a reaction and the rates of reaction. Factors that effect Rate of Reaction (R of R). Collision Theory Anything that will increase the number of and frequency of the collisions

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Kinetics and Equilibrium

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  1. Kinetics and Equilibrium

  2. Kinetics • The study of the mechanisms of a reaction and the rates of reaction.

  3. Factors that effect Rate of Reaction (R of R) • Collision Theory • Anything that will increase the number of and frequency of the collisions • More effective collisions

  4. Factors that Effect Rates of Reactions (T,A,P,S,N,C) • Temperature -(Average Kinetic Energy=motion) • Inc. Temperature = Increase R of R • Amount • Increase Amount (concentration) = Increase R of R • Pressure (g only) - Inc Pressure = increase R of R • Surface Area – Inc. S.A. = Inc. R of R • Nature of Reactants (Ionics > Covalents) • Due to their reactivity and the number of bonds needed to break

  5. Catalyst – anything that is added that will increase the R of R • If present will increase the R of R How? • By providing an alternative pathway for the Reaction by effecting 3 things • Ea of the Forward catalyzed Reaction • Ea of the Reverse Catlayzed Reaction • PE of the Activated complex

  6. Two Kinds of Reactions Endothermic • Absorb Energy • Heat + AB  A +B • Heat is a reactant • Break Bonds • + H Exothermic • Release Energy • A + B  AB + Heat • Heat is a product = Stability • Bond formation • - H

  7. (Most Effective Collisions)

  8. Entropy S Entropy is defined as the degree of randomness, disorder, chaos (s) – (l) – (aq) – (g)

  9. Gibbs Free energy G • A reaction will always proceed spontaneously if the sign for Gibbs free energy is (-) - G • The two conditions that favor a - G are : low energy - H Exothermic high entropy + S

  10. LeChatelier’s principle • States that when a system that is at equilibrium is placed under a stress, the systems equilibrium will shift in order to relieve the stress • Inc. (T) : will always favor endothermic reactions • Inc (P) : will always favor the side of less mole formation

  11. A + B C + D Equilibrium

  12. Acids and Bases

  13. Bases Acids & Bases Acids Sour Taste Reacts with certain metals on table J to yield H2(g) Great Electrolytes (Why?) Excellent Conductors of Electricity (Why?) Cause Acid/Base Indicators to change colors • Bitter • Slimy • Great Electrolytes (Why?) • Excellent conductors of Electricity (Why?) • Cause Acid/Base Indicators to change colors Acid reacts with Base to yield Salt and Water Called the “Neutralization Reaction”

  14. The Neutralization Reaction Acid + Base -------------> Salt + Water HCl + NaOH --------> NaCl + H2O What kind of Reaction do you See? Double Replacement

  15. Water + Salt --------> Acid + Base The Hydrolysis of a SaltThe Reverse Reaction Adding water to a salt! H2O + NaCl -------------> HCl + NaOH Called “The Parent Acid and Base”

  16. Base Definitions of Acid and Base Arrhenius Acid Any substance that yields (H+) as the only positive ion in solution HCl ------------> H+ + Cl- HBr ------------> H+ + Br- H3O+ ----------> H+ + HOH H3PO4 ---------> H+ + H2PO4- H2PO4 - -------> H+ + HPO4-2 HPO4-2 --------> H+ + PO4-3 Any Substance that yields (OH-) ion as the only (-) ion in solution (Recall: Goup I,II Metal with OH and NH4OH) NaOH --------> Na+ + OH- Ca(OH)2 -----> Ca+2 + 2OH- NH4OH ----> NH4+ + OH- Reminder: Do not confuse Base with Alcohols! (Hydrocarbon-OH) CH3OH CH3CH2OH

  17. AmphoterismAny Substance That can act as either acid or base H3O+ ----------> H+ + HOH HOH ------------> H+ + OH- H3PO4 ---------> H+ + H2PO4- H2PO4 - -------> H+ + HPO4-2 HPO4-2 --------> H+ + PO4-3

  18. Base Definitions of Acid and BaseBronsted - Lowery Acid Proton (H+) Donor Proton (H+) Acceptor H+ H+ H2O + H2O -------------> OH- + H3O+ Strong Acid (SA) ----------> H+ + Weak Base (WB) Weak Acid (WA) ------------> H+ + Strong Base (SB)

  19. Strong Acids and Strong Bases • Strong Acids • HCl • HBr • HI • H2SO4 • HNO3 • StrongBases • Group I M • Ca, Sr, Ba with OH

  20. pH Scale • pH Scale • Is a scale that is used to measure if a substance is an acid or base • Measures the Percent [H+] (The power of Hydrogen!)

  21. pH Scale • ****_____ • For every decrease in pH value, this represents a 10x Increase in [H+] • 5 <---------- 6 <------------ 7 <----------- 8 • 10 x 10 x 10 x <------------------------------------------------------------- 1000 x

  22. pH Calculations Ksp (The ionization of H2O) H2O <-----------> H+aq + OH-aq Keq = [H+] [OH-] Fact KH2O = 1 x 10 -14 1 x 10-14 = [H+] [OH-] [H+] = 1 x 10-7 [OH-] = 1x 10-7 Calculate pH pH = -log[H+] pOH = -log[OH-] pH = 7 pOH = 7 pH + pOH = 14

  23. pH calculations What are the pH values of the following? .1 M HCl .01 M HCl .001M HCl

  24. The Hydrolysis of a Salt! • Remember (it is the reverse reaction of a __________________ reaction) KCl + HOH -----> KOH + HCl How can we determine the pH of the resulting solution? Neutralization

  25. Titration • Def. A technique that is used to determine the strength of an unknown (acid or base) compared with a known (acid or base). • (coef A) MAVA = MBVB (coef B) We need an acid base indicator: Phenolphthalein Acid Base clear Pink

  26. Titration Technique • Steps. Slowly add base to flask (watch for a color change to pale pink) ***Do not go past the end point! (coef A) MAVA = MBVB (coef B)

  27. Titration

  28. Titration • (coef A) MAVA = MBVB (coef B)

  29. Titration and Calculations • (coef A) MAVA = MBVB (coef B) End Point

  30. Naming Acids This is Review! Binary (2 elements) Tiernary (3 elements) Always starts with “Hydro” Name the Non-Metal (Chlorine) Drop the ending, add ic acid M(PI) M(PI) ate – icite - ous H2SO4 Sulfuric Acid HNO3 Nitric Acid HNO2 Sulfurous Acid H2SO3 Nitrous Acid HCl Hydrochloric Acid HBrHydrobromic Acid HI Hydroiodic Acid

  31. Redox and electrochemistry

  32. Assigning oxidation numbers • Metals in group 1 have (+1) ox #, group 2 metals (+2) • Any single “Pure” element = 0 • Hydrogen is always (+1) except in metal hydride (-1) LiH 4. Oxygen is always (-2) exceptions: With flourine (flouide) +2 OF2 In Peroxides (-1) H2O2 • The sum of all oxidation #’s must = 0 • The sum of all Polyatomic ions must equal the charge of that ion

  33. Assigning oxidation numbers • Binary Compounds _____ 1. Start with the Non Metal 2. Finish with the Metal HCl 3. Sum up must = 0 _______ MgCl

  34. Assigning oxidation numbers • Ternary Compounds _____ 1. Start with the Non Metal (Oxygen) H2SO4 2. Go to the Metal (H) 3. finish up in the middle 4. Sum up must = 0 __________ Mg(NO3)2

  35. Redox Reactions(reactions where both Oxidation and Reduction take place) 1. Oxidation Reduction The gain of Electrons Half Reaction 2e- + Mg+2 Mg0 (reactant) Loss of Electrons Half Reactions Mg0 Mg+2 + 2e- (product) Leo says ger Oil rig Causes the Reduction of the other elements Acts as a REDUCING AGENT (R.A.) Causes the other species to be Oxidized. Acts as the Oxidation Agent (O.A.)

  36. Writing half reactionsdetermine the Ox / redra / oa All Redox Reactions must demonstrate conservation of both Mass and Charge Steps (Now this is Doc’s Method! …..Capisco?) 1. Assign the Ox #’s 2. Record the changes 3. Record e- loss / e- gain 4. Determine the species that is oxidized (RA) and reduced (OA) 5. Balance if unequal Ca + Cl2 CaCl2 ***HHH___

  37. Electrochemical cellSpontaneous cell (battery)Voltaic cell, galvanic cell Al Cu (****Chemical energy  electrical ****) Remember: A RED CAT IS AN OX TABLE J and…….A RED CAT GETS FAT!!!!!!

  38. Electrochemical cellSpontaneous cell (battery)Voltaic cell, galvanic cell

  39. Electrochemical cellSpontaneous cell (battery)Voltaic cellgalvanic cell

  40. Electrochemical cellSpontaneous cell (battery)Voltaic cellgalvanic cell

  41. Electrochemical cellSpontaneous cell (battery)Voltaic cell, galvanic cell

  42. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis(****electrical  chemical energy****)

  43. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis (****electrical  chemical energy****)

  44. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis of water!!!

  45. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis of water!!!

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