Transition Metals and Redox Reactions: Exam 3 Review and Lecture Announcements

Chem. 1B 11/22 Lecture

Announcements I Lab No Lab this Wednesday (or Thursday) Exam 3 Next Week on Thursday On electrochemistry and Chapter 24 Help Session Tues. afternoon (joint with PALs?? I can do 4:00 to 5:00)

Announcements II Mastering Ch. 24 assignment due 11/26 Today s Lecture Transition Elements (Ch. 24) Properties of Coordination Complexes light absorption and magnetic properties - Completing Exam 3 Material + Some Practice Problems Organic Chemistry (Ch. 20)

Chapter 24 Transition Metals Questions cont. from last time 4. Ti3+ is purple while Ti4+is uncolored. Explain. 5. For which of the following metals in octahedral complexes does the ligand NOT play a role in the number of unpaired electrons? a) Mn2+ b) Fe3+ c) Co2+ 6. [Fe(en)3]3+undergoes a ligand replacement reaction and forms [FeX6]3-. The new complex absorbs at shorter wavelengths. What do we know about the strength of X as a ligand? d) Ni2+

Exam 3 Review Equations I will give: Grxn= Grxn + RTlnQ (more Thermo) G = -nFE and E = E cell- (0.0592/n)logQ Equations you should know: q = It (constant I); q = nF Ecell = Ered - Eox E (= ) = hc/

Exam 3 Review Chapter 18 Redox Reactions Be able to determine oxidation states Determine which element is being reduced and which is being oxidized Know all steps in reaction balancing and be able to apply (see example questions) Know three ways in which redox reactions can occur (beakers, voltaic cells, electrolytic cells)

Exam 3 Review Chapter 18 Voltaic Cells Know components of voltaic cell (anode, cathode, cell bridge, rest of circuit) Know charge of and reaction type at each electrode Know flow (direction) of electrons and ions Know purpose of voltaic cell Know cell notation

Exam 3 Review Chapter 18 Standard Electrode (Reduction) Potentials Know basis (how it could be measured) Know standard conditions Be able to use table to: Determine E cell(from combining two standard electrodes) + reaction direction Know what makes a good reducing/oxidizing agent What metals can be oxidized in acid

Exam 3 Review Chapter 18 Relating Thermodynamics to Cell Potential Be able to convert between G , K, and E Know standard conditions Use of the Nernst Equation: For calculation of Ecell(non-standard conditions) For determination of concentration For determination of E cell(from Emeasuredand Q)

Exam 3 Review Chapter 18 Batteries (Application of Voltaic Cells) Be able to relate charge or lifetime to moles of reactants (q = nF) Know requirements for rechargeable batteries Know fuel cell basics Electrolysis Know main differences with voltaic cells Be able to predict reduction/oxidation reactions

Exam 3 Review Chapter 18 Corrosion Understand tendency of metals to oxidize Understand requirement of sacraficial metals

Exam 3 Review Chapter 24 Transition Metal Names Know names of row 4 elements + d8 to d10 (row 5 and 6) Transition Metal Properties Know electron configurations of transition metals plus ions (including rule exceptions in first row) Know size (mostly decreases across row) and oxidation state trends

Exam 3 Review Chapter 24 Coordination Complexes Know requirement for ligands Know types of ligands (mono-, bi-, polydentate) Know major geometries (linear, square planar, tetrahedral, octahedral) plus associated ligand numbers and structures Know how to relate name to formulas (we are not worrying about bis-, linkage ligands in names, and a table of latin roots will be provided)

Exam 3 Review Chapter 24 Coordination Complexes - Isomers Know what structural isomers are Know requirement for linkage isomers Be able to tell if cis- trans- or fac- mer- isomers exist Know what optical isomers are Be able to predict the correct number of isomers

Exam 3 Review Chapter 24 Bonding Theory Know where metal ligand bonds come from Know which d orbitals overlap more with ligand bonds in octahedral complexes and which overlap less Know how overlap leads to a split in the d orbital energies Know difference between low spin and high spin filling of d orbitals

Exam 3 Review Chapter 24 Bonding Theory cont. Know how ligand (e.g. strong vs. weak) affects filling and of coordination complexes Know how metal charge affects of coordination complexes Be able to predict the d orbital electron configuration of coordination complexes (if known whether ligand is strong or weak) Know what causes coordination complexes to absorb light in visible, plus be able to calculate from or visa versa

Exam 3 Review Chapter 24 Bonding Theory cont. Be able to determine number of unpaired electrons and how that affects magnetic properties of complexes Understand why differences in energy levels occur for other geometries (tetrahedral, square planar)

Exam 3 Review Questions I Reaction Ag+(aq) + e- Cu2+(aq) + 2e- 2H+(aq) + 2e- Ni2+(aq) + 2e- Cd2+(aq) + 2e- Fe2+(aq) + 2e- E (V) +0.80 +0.34 0.00 -0.23 -0.40 -0.45 Ag(s) Cu(s) H2(g) Ni(s) Cd(s) Fe(s) 1. Which of the metals (in oxidation state of zero) in the list above are oxidized by H+? a) Ni and Cd b) Ni only c) Cd only e) Ni, Cd, and Fe d) Cu and Ag 2. In the following cell, the measured voltage is 0.99 V. Determine x (the concentration of AgNO3(aq) in half of the cell. cell: Ni(s)|NiCl2(aq, 1.0 M)||AgNO3(aq, x M)|Ag(s) a) 0.21 M b) 0.045 M c) 0.459 M d) 2.2 M e) 4.8 M

Exam 3 Review Questions II Reaction Ag+(aq) + e- Cu2+(aq) + 2e- 2H+(aq) + 2e- Ni2+(aq) + 2e- Fe2+(aq) + 2e- E (V) +0.80 +0.34 0.00 -0.23 -0.45 Ag(s) Cu(s) H2(g) Ni(s) Fe(s) 3. Which of the following reactants can oxidize copper metal (Cu(s)) under standard conditions? a) Ag+(aq) b) H+(aq) c) Ni2+(aq) d) Fe2+(aq) e) any of these 4. A voltaic cell is made under standard conditions by Fe(s) and FeCl2(aq) in one half cell and AgNO3(aq) and Ag(s) in another half cell. The voltage from the silver (+) to the iron electrode (-) will be: a) -0.10 V b) +0.10 V c) +0.35 V d) +1.25 V e) +2.05 V

Exam 3 Review Questions III 5. The following reaction is an UNBALANCED reaction showing reactants and products of a redox reaction: HClO(aq) + Cr(s) Cl2(g) + Cr3+(aq) When balanced (can assume acidic conditions), the coefficients in front of HClO and Cr (with no fractional coefficients anywhere in the equation) are: a) 1 and 1 b) 2 and 1 c) 3 and 1 d) 3 and 2 e) 6 and 2, respectively. 6. In coordination complexes, electrons in bonds between ligands and metals almost always come from: a) metal s shells b) metal d shells c) ligand lone pair electrons d) ligand inner shell electrons e) ligand sigma bonds

Exam 3 Review Questions IV 7. Given the complex [Co(NO2)6]4-, give a) oxidation state on Co b) # d shell electrons, c) # unpaired electrons if you know NO2-is a strong ligand 8. Can the above compound form any isomers?

Chapter 20 Organic Chemistry Introduction Organic Chemistry is a major area of study (we offer 7 organic chemistry classes at the undergraduate level) In ~1 week, we only have time to introduce basic principles of organic chemistry

Chapter 20 Organic Chemistry Overview Nature of Carbon Carbon Bonds Hydrocarbons (structure, naming and isomers) Reactions Aromatic Hydrocarbons Functional Groups

Chapter 20 Organic Chemistry Nature of Carbon Carbon Bonds Carbon is one of the few elements that form fairly stable bonds with itself Most alkanes (hydrocarbons with only single bonds), while combustible in air (more stable as CO2+ H2O), have negative Gf Carbon likes to form 4 bonds ([He]2s22p2, but mostly forms sp to sp3hybrid bonds)

Chapter 20 Organic Chemistry Nature of Carbon Carbon Bonds Simplest hydrocarbon is CH4, methane, in which sp3hybridization occurs (tetrahedral geometry) As carbon carbon bonds are common, in alkanes, they also occur with sp3 hybridization (tetrahedral for each C atom)