LAST MINUTE REEEEEDDDO Flashcards
What is the flow of electrons
From anode to cathode
What takes place at anode and what charge is it
Oxidation takes place at anode as it is a loss of electrons and it is negatively charged
What takes place at cathode and what charge is it
Reduction takes place at cathode as it is a gain in electrons and is positively charged.
What is the purpose of salt bridge
IS to connect the half cells and maintain electrical neutrality. This is done by allowing ions to move to the cells to balance out the charges. If there was no salt bridge a build up of charge would occur in both cells and reaction would cease to exist.
E0 value
The standard reduction potential (Eo value) is a measure of that reaction’s potential to pull in (gain electrons or undergo reduction) relative to the standard hydrogen half cell. This is determined by oxidation number - reductant number
When predicting spontaneous redox reactions using top left bottom left
Pb2+(aq) is a strong enough oxidising agent to force Sn(s) to lose electrons (oxidise) to form Sn2+ (aq). Pb2+(aq) will gain the electrons and become Pb(s).
It is not reliable if it is not perfomed in standard conditions.
Recharging in secondary cells
To recharge the cell, electrical energy is used to force the original products to turn back into the original reactants. This is done by forcing electrons to travel in the opposite direction to when discharge is occurring.
Converts electrical energy back into chemical energy
What happens to reactions when secondary cell recharging
When a secondary cell is recharged, the reactions are reversed at each electrode:
The anode becomes positive as the external power source withdraws electrons. The electron deficiency causes oxidation.
The cathode becomes negative as the external power source causes an excess of electrons. The excess electrons causes reduction.
Cool thing about fuel cells
Always has a constant supply of energy due to a constant supply of reactants. H2 and O2. O2 is always the oxidant. (is gonna be reduced) (reduction)
Pros of fuel cells
clean energy - doesnt produce greenhouse gases, electricity will continuously be supplied as long as fuel is supplied, H2 gas is produced by biomass.
Cons of fuel cells
Poor storage as h2 is lighter than air so it has a tendency to escape, is expensive, effiency is 60%
difference in fuel cell and galavnic cell
Electrodes are porous in fuel cells and has a constant supply of reactants.
