Unit 6 - Electrochemistry Flashcards
What is a battery?
An electrochemical cell inter-converting chemical and electric energy. Provides electric current
What is electrolysis?
A chemical reaction due to electric current being passed through aqueous solution
2 Types electrochemical cells
Galvanic (voltaic) –> spontaneous
Electrolytic –> non-spontaenous
What is oxidation?
Loss of electroncs
What is reduction?
Gain of electrons
What are the 3 components of a Galvanic or Daniell cell?
Anode, Cathode, and a salt bridge with an inert electrolyte
Describe the anode
- the electrode where OXIDATION occurs
- the electrode where ELECTRONS are PRODUCED
- where ANIONS migrate TOWARD
- has a negative sign
Describe the cathode
- the electrode where REDUCTION occurs
- the electrode where ELECTRONS are CONSUMED
- where CATIONS migrate TOWARD
- has positive sign
What is electro motive force (EMF)?
The force or electrical POTENTIAL that pushes the negatively charged electronics away from the anode and pulls toward the cathode. Also called cell potential (E) or voltage (V)
On the standard reduction table, is a negative E compared to a positive E a stronger or weaker oxidizing agent?
Weaker
What are 4 things to know about standard reduction potentials
- Cell parts are in standard states
- E for oxidation is negative for reduction
- Half-reactions are written as reductions
- Half-cell potentials are intensive ie potential does not change depending on amount of moles
How many cells in series of H2SO4 and PbO2 are required to supply enough voltage for a car battery?
6 cells in series
When is the battery dead?
When the spongy PbO2 (cathode) becomes hard
Advantages of Lithium batteries?
- Light
- High energy density
- High voltage
- low charge loss
- no memory effect
- long cycle life
Disadvantages of Lithium batteries
- Degrades faster when exposed to heat
- Expensive
- Safety issues for large sizes
