lecture 3 fr Flashcards
what is a cell
2 electrodes in an electrolyte
- ions can move between the 2 electrodes + generate an external current (e- moving) that can be measured
- an external potential is applied to the electrodes to drive ions
2 separate cells
- half cells
- 2 electrodes in 2 diff electrolytes
- salt bridge connects them + contains ions which travel at the same speed
- gel can be used to slow down salt bridge ion mobility
- salt bridge should be inert: NaCl, KCl
galvanic cell is also called a
prototypic battery
galvanic cell
- current is generated in a spontaneous way
- can be used as a battery
- batteries are not at equilibrium
if u have voltage: E=+ and G=-
electrolytic cells (external potential)
- direction of reaction is determined by an external potential
- used for electrolysis
- used to split water to store renewable energy
what process occurs within electrochemical cells
redox reactions
what happens at the cathode
RHS
reduction occurs at the cathode
ions -> solid
what happens at the anode
oxidation
solid -> ions
all half reactions are
reduction reactions
daniel cell
Zn in ZnSO4
Cu in CuSO4
zn|znso4 || cuso4 | cu
remember states
types of electrodes
gas
insoluble salt
redox electrode
combo of diff half cells
combo of diff half cells
gas electrode
hydrogen
Pt|H2(g) | H+ (aq)
1 atm gas
1 moldm-3 H+ (aq)
insoluble salt electrode
metal electrode covered in insoluble salt
MX
where X is the solution it’s in
insoluble salt electrode example
Ag(s) | AgCl(s) | Cl-(aq)
Ag is metal
AgCl = salt
Cl= what it’s immersed in
redox electrode
2 diff oxidation states in solution
same element
inert electrode
Fe3+ and Fe2+
