In-class oral Q & A to see if you know your redox sh*t, and, that you understood this week’s %$# lab

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

Mg(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 (g) 2Al(s) + 3CuSO 4 (aq)  Al 2 (SO 4 ) 3 (aq) + 3 Cu(s) Which element oxidized ? Which element reduced ? Which element oxidized ? Which element reduced ? PRACTICE ASSIGNING OXIDATION #(cont.) Mg H Al Cu w/demo

What are the oxidation # for H, Mn and O in HMnO 4 A.H=+1, Mn=+3, O=-1 B.H=+1, Mn =+7, O=-2 C.H=0, Mn=8, O =-2 D.H=-1, Mn = 9, O=-2

What is oxidized and reduced in the reaction: PbO + CO  Pb+CO 2 A.O reduced, Pb oxidized B.C reduced, Pb oxidized C.Pb reduced, O oxidized D.Pb reduced, C oxidized

What is oxidized and reduced in the reaction: CH 4 +O 2  CO 2 +H 2 O A.C oxidized, O reduced B.H oxidized, C reduced C.C oxidized, H reduced D.O oxidized. C reduced

SPECTACULAR REDOX REACTION BEHAVIOR 2Al o (s) + Fe 2 O 3 (s)  2Fe 0 (liq)+Al 2 O 3 (s) 3)let’s see the reaction in the `flesh’ (why we don’t do this one in class…) Which element oxidized ? Which element reduced ? Al Fe 1)assign oxidation # 2) Who does what? 1) Thermite reaction

SPECTACULAR REDOX REACTION BEHAVIOR (continued) Example 2: Combustion CH 4 +2O 2  CO 2 +2H 2 O 1) Assign Oxidation # Which element oxidized ? Which element reduced ? 2) Who does what? C O BURN BABY, BURN

: 2Na + Cl 2  NaCl (table salt) SPECTACULAR REDOX REACTION BEHAVIOR (continued) Example 3: Combination redox 1) Assign Oxidation # Which element oxidized ? Which element reduced ? 2) Who does what? 3) Let’s see it

SPECTACULAR REDOX REACTION BEHAVIOR (continued) Example 4: Exchange (how chemists tear apart beer cans with their bare if wimpy hands) 2Al 0 + 3Cu 2+  2Al Cu o 1)Assign oxidation numbers Which element oxidized ? Which element reduced ? 2) Who does what? Al Cu 2+

C 12 H 22 O K Cl O 3  11H 2 O + 12CO 2 + 8KCl 5) EXAMPLE 5 Decomposition redox: aka The DEATH TO SKITTLES REACTION SPECTACULAR REDOX REACTION BEHAVIOR (continued) Ox Red And now, the dangerous, scary In-class demo…

One other unique and highly useful feature of redox reactions … The oxidation and reduction can be separated in space and you can still run the reaction as a `cell’ or ‘battery’

Example: Cu-Mg cell Cu 2+ + Mg o  Cu o +Mg 2+ The complete redox reaction Reduction half reaction: Cu 2+ +2e -  Cu o cathode Oxidation half reaction: Mg o  Mg 2+ +2e- Gains 2e - Loses 2e- anode Cu 2+ + Mg o  Cu o +Mg 2+

The experimental set-up of (Mg|Mg 2+ ||Cu 2+ |Cu) cell anode cathode LOAD Electron flow out of anode OxidationReduction Mg 0  Mg 2+ +2e - Cu 2+ +2e -  Cu o NaCl bridge Na +   Cl -

Cu +2 | Cu Mg|Mg 2+ The Potato clock relies on O 2 to cause Cu to oxidize to CuO which dissolves to form Cu +2 (aq). Any `juicy’ vegetable or fruit can serve as electrolyte source e - out e - in OXRED ~1.5 V

Ford Focus all electric car High surface area lithium ion batteries

Li x C 6  xLi + + 6C + xe- Cathode (right side=red) 0 0 Power cycle – what happens as you drive +1 Anode (left side =ox) Li o embedded in `intercalation’ compounds on both sides Li 1-x CoO 2 + xe - + xLi +  LiCoO 2 Key Chemistry trick: +1 LOAD