Oxidation Rules
Neutral Compound = 0 (NO -) |
Ion= ion charge (w/ -) |
+1 w/ non-metals (Hydrogen) |
Oxygen usually -2, -1 in peroxide (H2O2) |
-1 w/ metals (H) |
Group 1A: always +1 |
Halogens: usually -1, positive w/ oxygen |
Group 2A: always +2 |
F always -1 |
Monatomic Ions: made with one atom, same as their charges |
EXAMPLE: |
|
|
Redox Equations
Reduction: gain of electrons |
Oxidation: loss of electrons |
e-: electron |
OIL: oxidation is loss (of electrons) |
RIG: reduction is gain (of electrons) |
OIL as half reaction: Na > Na(+) + e- |
RIG as half reaction: Cl + e- > Cl- |
for oxidation: e- on right |
for reduction: e- is on left |
If OX # ^ it is OIL |
EXAMPLE: |
If OX # goes down it is RIG |
Batteries
Definition: a series of voltaic cells that produces a voltage that is the sum of the voltages of the individual cells |
Types |
Dry Cell Battery: Typical AA, AAA, C, & D |
Lead Storage: 12 V (6 cells that each provide 2V) |
Anode: Zinc, Cathode: graphite, all immersed in KOH |
Anode: Lead, Cathode: PbO2, all immersed in sulfiric acid |
Advantage: cheap and small |
must be recycled! |
Disadvantage: not recharagable |
to keep electrodes from touching, wood or glass fiber spacers are used |
Recharagable Batteris: includes lithium ion, nickel-cadmium, and nickel metal hydride batteries |
Voltage may vary as the H2SO4 is used, even after recharging |
Built in or separate charger |
Advantage: large voltage, can be recharged |
Advantage: rechargable |
Disadvantage: heavy, expensive, takes up a lot of space |
Disadvantage: cost |
Fuel Cells: 2H2(g) + O2 (g) > 2H2O(I) |
| |
Hydrogen is oxidized, electrons used to create electricity |
| |
Used in spacecraft, too $$ for general use |
| |
Adv: no recharge, only emission is water |
| |
Dis: cost |
|
|
Calcuating Cell Potential
Find correct half reactions on green sheet |
Down reduction potential, oxidation more likely (more positive voltage) |
Write down half reactions on paper along with voltage |
higher voltage is e red, flip other half reaction to make oxidation and change sign given on green sheet (write it backwards) |
Add the half reactions and voltages together (e- should cancel) |
|
|
Writing Half Reactions
Assign oxidation numbers |
Ex: Zn + Cu2+ > Zn2+ + Cu |
Put the atoms with changing oxidation numbers in a separate reaction |
Balance all atoms |
Balance charge by adding e- to more positive side |
Voltaic Cell
Cathode: site of reduction (gaining e-) |
Neutral atoms make solid metal |
Anode: sire of oxidation (losing e-) |
Metal ions can usually dissolve in water |
Definition: devices that use a chemical reaction to create electricity |
Cell Notation/Diagram: two half reactions combined |
| |
Ex: Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s) |
|
Created By
Metadata
Comments
No comments yet. Add yours below!
Add a Comment
Related Cheat Sheets
More Cheat Sheets by sunyzz