chem whatarethemechanismsofchemicalchange
Reactivity 3.2.5 - oxidation occurs at the anode and reduction occurs at the cathode in electrochemical cells
voltaic and electrolytic cells are collectively known as electrochemical cells.
- voltaic (galvanic) cells generate electricity from chemical reactions
- a spontaneous chemical reaction drives electrons around a circuit
- electrolytic cells drive chemical reactions using electrical energy
- an electric current reverses the normal directions of chemical change, non-spontaneous reactions occur
| voltaic | electrolytic | |
|---|---|---|
| type of reaction | spontaneous | non-spontaneous |
| electrode of oxidation | anode | anode |
| electrode of reduction | cathode | cathode |
| polarity of anode | negative | positive |
| polarity of cathode | positive | negative |
they are the reverse of each other
- a voltaic cell converts chemical energy to electrical energy
- an electrolytic cell converts electrical energy to chemical energy when an electric current drives a reaction with a negative value for
from the equilibrium
| type of cell | type of reaction | ||
|---|---|---|---|
| voltaic | spontaneous | ||
| electrolytic | non-spontaneous | ||
| equilibrium | dead battery |
primary cell:
feature:
advantages:
- long shelf life
- cheap
- low maintenance
- energy dense
- lightweight
disadvantages:
- non-rechargeable
- high-environmental impact
- self-discharge
uses:
secondary cell:
feature:
advantages:
- rechargeable
- reuseable
- long-term cost efficient
- energy dense
- high performance and power
disadvantages:
- high initial costs
- limited cycle life
- maintenance required
- self-discharge