voltaic and electrolytic cells Flashcards
when would an inert electrode be used in voltaic cells
when a half cell has no solid metal involved a Pt electrode is used to connect to the circuit
outline the differences between electrolytic and voltaic cells
- electrolytic cells require a battery, voltaic does not
- reactions in voltaic cells are spontaneous, not in electrolytic
- electrolytic cells convert electrical energy into chemical reactions; voltaic cells convert chemical energy into electrical energy
- voltaic cells require a salt bridge, electrolytic cells do not
- voltaic cell has two separate solutions, electrolytic only has one
- anode in electrolytic cells is positive, but negative in voltaic cells
two ways current is conducted in a voltaic cell
- movement of ions in the salt bridge
- electron flows in wires
outline the function of salt bridge in the voltaic cell
salt bridge completes the circuit by allowing free movement of ions to balance the charges
how do you draw the cell diagram convention for a voltaic cell
R O O R (oxidation on the left side, two lines to denote the salt bridge in the middle, reduction on the right side)
most oxidized states in the center, most reduced on the sides
how do you determine which element gets reduced or oxidized
oxidized = most negative Ecell
reduced = most positive Ecell
how can you determine whether or not the reaction is spontaneous
if Ered - Eox > 0
if it were an aq solution of NaCl undergoing electrolysis, why would H2 form at the cathode
Hydrogen is a stronger oxidizing agent (i.e. more likely to get reduced) because it is less reactive than Na+ (which is more likely to lose an e-)
standard electrode potential
The potential difference obtained under standard conditions when a half-cell is connected to a standard hydrogen electrode.
which electrode gets smaller
the anode, because it is being oxidized so the atoms become ions when they lose e- and dissolve in the solution instead
