Redox and Electrochemistry Flashcards
Oxidation is when
OIL RIG
Loss of electrons , gain of oxygen
Reduction is when
OIL RIG
Gain of electrons , loss of oxygen
What is the cell notation for this electrochemical cell?
Explain why there is potential to do electric work between two half-cells
Charge builds up at Phase Boundary
Half Reaction equilibria in both half cells (not redox)
Both half-cells are held at different electric potentials
Work is done when the charge moves between electric potentials.
How do you calculate the Maximum electrical work?
Charge * Electric Field Strength
What is cell potential
Comparison of the relative oxidative and reductive abilities of a half cell.
what is a state function
a function that is independent of the journey taken, just dependant on the state of the current system.
What is the SHE
standard hydrogen electrode
Reference for all other potential measurements
0.00V
how do you calculate E Cell
E Cathode - E anode
Eright - Eleft
What happens at the cathode
Reduction
What happens at the anode
Oxidation
If an E Cell is more positive what does it mean
Better oxidising agent (Easier to reduce)
If an E Cell is more negative what does it mean
Better reducing agent (Easier to oxidise)
use free gibs to derive an equation for E Cell in terms of the Equilibrium constant and Temperature
What is corrosion
conversion of metals to more stable forms such as oxides hydroxides or sulfides
destroys metal
What environmental conditions accelerate corrosion?
Humidity
Temperature
Chlorine Ions on Iron
Acids
Microbes
Explain Galvanic Corrosion
Metal is in contact with water/oxidising solution.
acts as a contact between 2 dissimilar metals
contact between 2 half cells.
Explain Uniform Corrosion
What is it enhanced by
Metal is in contact with water/oxidising solution.
acts as a contact between 2 identical metals
contact between 2 half cells at some distance undergoing different processes.
enhanced by the presence of cl- or similar ion
Explain Barrier Protection of Corrosion
Anodization
creation of inert oxide later on top of the metal
pain, enamel , plating
Explain the Cathodic Protection of Corrosion
The sacrificial anode attached to piece to protect it, needs to be replaced regularly
What reactions occur in a lead acid battery (Car Battery)
What reactions occur in an alkaline battery (Car Battery)
how to you calculate the emf of a half cell
