Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
15 Cards in this Set
- Front
- Back
|
Oxidation
|
Losing electrons
Gaining bonds to electronegative atoms Losing Bonds to less electronegative atoms |
|
|
Reduction
|
Gaining electrons
Gaining bonds to less electronegative atoms Losing Bonds to more electronegative atoms |
|
|
Assigning Oxidation States
|
1. The oxidation state of any element in its standard state is 0
2. The sum of the oxidation states = the molecules charge 3. Group 1 metals have a +1 oxidation state, and Group 2 metals have a oxidation +2 state 4. Flourine has a -1 oxidation 5. Hydrogen has a +1 oxidation state when bonded to something more electronegative than carbon, a -1 oxidation state when bonded to an atom less electronegatice than carbon, and a 0 oxidation state when bonded to carbon. 6. Oxygen has a -2 oxydation state. 7. The rest of the halogens have a -1 oxidation state and the atoms of the oxygen family have a -2 oxidation state |
|
|
Reading Reduction potential chart
|
- reduction potential are for reactants
- The more positive the reduction potential the more easy it is to reduce the reactant - more elctronegative species tend to be easier to reduce - oxidation potential is for the products, where the more positive the value (after you flip the sign since your flipping the equation) the easier it is to oxidize it |
|
|
Cell Potentials
|
Ecell = Ered + Eox
E cell < 0 (nonspontaneous) E cell > 0 spontaneous ∆G = -nFEcell = qE where n = the # of mol of electrons F = Faraday's constant |
|
|
Standard Cell Potential
|
Standard Cell Potential
E⁰ = RT/nF ln K |
|
|
Actual Cell Potential (instantaneous)
|
E = E⁰ - RT/nF ln Q
a cell at K will have E = 0 @ which point battery will not pump out any more electricity |
|
|
Time Based Cell Calculations
|
Over time a quantity of electrons can be used to do work (i.e. electroplating)
Given a current and a time the moles of electron can be determined I = nF/t = q/t where n = moles of electrons |
|
|
Reducing Agents
|
Compund that causes something else to gain electrons. It will be oxidized.
high oxidation potentials (+) (very negative reduction potentials) H₂ , neutral metals, MEHx (metal, some element, hydrogen) (LiAlH₄, NaBH, etc.) agents = reactants |
|
|
Oxidizing Agents
|
Cause other elements to be oxidized. Easily reduced. Elements with very positive reduction potentials.
Neutral nonmetals, (O₂, F₂) MOx (MnO₄⁻, CrO₃⁻, etc.) agents = reactants |
|
|
Electrochemical cells
|
All cells must consist of....
- two or MORE electrodes made from conductive material (metals and graphite are common) - Electrolyte bridging the gap between the electrodes (a salt bridge is an example) - Must have a circuit for a cell to do anything |
|
|
Galvanic cell
|
a galvanic cell will be part of a complete circuit with no external power source (exampe: battery in a circuit)
spontaneous, posive Ecell Discharging battery, so overtime output will decrease Often called voltaic |
|
|
Electrochemical Cell - Cathode
|
The cathode is where...
- reduction occurs - Current (+) flows from - Cations flow towards - Plating occurs - (+) for galvaninc, (-) for electrolytic - H₂ is produced in aq soln |
|
|
Electrochemical Cell - Anode
|
The Anode is where...
-Oxidation occurs - Electrons flow from - Anions flow toward - pitting occurs -O₂ is produced in aq soln -(+) electrolytic, (-) galvanic |
|
|
Electrolytic Cells
|
An electrolytic cell will be part of complete circuit with an external power source (cell not driving force)
nonspontaneous (-Ecell) Recharging batteries current flows backwards from that of a galvanic cell so ions and electrons move the opposite way as well anode becomes cathode and vice versus Voltage is said to be negative since orientation of current flow has been switched. Takes more voltage to recharge than the voltage of the galvanic cell |
