Electrochemistry Flashcards
Equation for Faraday Constant, Avogadro Constant & Charge on Electron
F = Le
E can be found in data booklet (charge of electron)
Steps to determine mass of substance produced at electrode
1) Q = I x t [charge = current x time(s)]
2) charge/96500 = no of mole of electrons
3) use mole ratio to determine mole of substance
4) mole of substance x Mr = mass of substance
Electrolysis: What is the positive and negative terminal and what happens?
Anode:
- positive terminal
- negative ions attracted
- oxidation (loss of e)
- choose ion with more negative value
Cathode:
- negative terminal
- positive ions attracted
- reduction (gain of e)
- choose ion with more positive value
Electrolysis: Molten, what happens at anode and cathode?
Cathode:
- reduction (gain of e)
- positive ions attracted
Anode:
- oxidation (loss of e)
- negative ions attracted
Electrolysis: Aqueous solution, what forms at CATHODE
- can form either metal or H2
- metal below H (positive E) = metal
- metal high above H (negative E) = H2
- metal from Pb to Zn:
- concentrated = metal
- dilute = H2
Electrolysis: What forms at ANODE?
-can form either Halogen or O2
- conc= Halogen
- dilute = O2
Electrolysis: what happens if electrode is NOT INERT
Nothing left on anode but electrode
On cathode, substance will form
Redox Series / Electrode potential
Please stop calling me a careless zebra instead try learning how copper saves gold
K Na Ca Mg Al C Zn Fe Pb H Cu Ag Au
Electrolysis: how to sub in values to determine new e cell when the solution is concentrated or dilute
When equilibrium moves forward, +0.2
When equilibrium moves backward, -0.2
Standard electrode potential
The potential difference of a half cell measured under standard conditions with standard hydrogen electrode as another half cell
Standard Cell Potential
The potential difference between 2 half cella under standard conditions where concentration is 1moldm-3, 298K and 1 atm
Describe Standard Hydrogen Electrode
H2 gas at 1 atm pumped in
Platinum electrode
1moldm-3 and 298K H+
Describe a standard cell
Same conditions as SHE
But with added salt bridge and voltmeter
What happens when the metal is more reactive
Higher tendency to lose e
Undergoes oxidation
Good reducing agent
Equilibrium lies to left
E value is more negative
Equation for total electrode potential
E cell = E reduction - E oxidation
This automatically changes the sign
Only change it if they give oxidation values
