Chapter 13 Flashcards
electrochemical cells include ____ and ___ cells
voltaic and electrolytic cells
voltaic cells are always ______
spontaneous
voltaic cells use _____ to transform ____ into _____
redox reactions
chemical potential energy
electrical energy
voltaic cell process
electrodes are spectated and the electrons lost by the one electrode flow in one direction (producing electrical current) towards the other electrode
what are the anode and cathode in the voltaic cell diagram
the solid sticks
cathode definition
electrode where reduction occurs
cathode charge
positive
anode definition
electrode where oxidization occurs
anode charge
negative
external circuit definition
wire connecting anode to cathode
electrons travel from ___ to ____
anode to cathode
salt bridge/ porous cup definition
maintains the electro neutrality of solutions
salt bridge/ porous cup doesn’t allow _____
the ions of the two cell solutions from coming into contact with the opposite electrode
why must the salt bridge be carefully selected
so it doesn’t precipitate out any of the ions of the cell solution
the salt bridge is composed of ____ and ___
anions and cations
anions definition
negative ions, travel towards the anode
cations definition
positive ions, travel towards the cathode
electrolyte definition
something in solution
steps for determining anode and cathode in voltaic cell
1) determine SOA and SRA
- list everything you have and consult redox table
2) assign anode and cathode
- anode=where oxidization occurs
- cathode=where réductions occurs
steps for determining half reactions in voltaic cell (and note for steps 1 and 2)
1) write out half reaction of anode
- from redox table
2) write out half reaction of cathode
- from redox table
3) determine SOA and SRA based on ON’s of half reactions
4) write out oxi half reaction
5) write out red half reaction
* for steps 1 and 2: write reactions in regular way
decrease in mass
the one being oxidized (since it’s losing electrons)
increase in mass
the one being reduced (since it’s gaining electrons)
brighter colour
the one being oxidized
paler colour
the one being reduced
stays colourless
not in the table of “common aqueous ions” in data booklet
anion movement
arrow pouting towards anode
action movement
arrow pointing towards cathode
electrons movement
arrow pointing to cathode (since electrons flow form anode to cathode)
inert electrodes definition and 2 examples
electrode that is made form a material not involved in the reaction
Ex) Platinum (Pt) and graphite (C)
purpose of inert electrodes
are there to complete the circuit
cell notation: ll
salt bridge/ porous barrier
cell notation: l
phase boundary
in cell notation the ____ is always on the LEFT
anode
steps for cell notation
fill in
cell potential definition
electrical potential energy different between two charges
cell potential in voltaic cells definition
the electrical potential energy difference between two electrodes
factors affecting cell potential
- electrodes used
- temp
- concentration of electrolyte solutions
- pressure (only if dealing with gases)
standard cell potential is measured using a ____
voltmeter
what is the reference electrode in the redox table
hydrogen
cell potential formula (and what is everything measured in)
Ecell= Ecathode - Eanode
everything measured in volts
Ecell > O
reaction WILL proceed spontaneously (must be like this for voltaic)
Ecell< 0
reaction WON’T proceed spontaneously
steps for calculating standard cell potential
1) write red and oxi half reactions
- determine OA and RA using redox table
2) determine anode and cathode
3) write down reduction potentials from data booklet
4) use standard cell formula to solve for unknown
How to isolate for Er cathode
add Er anode to both sides
how to isolate for Er anode
fill in
when reference half cell is changed: reduction potentials ___ change
DO
when reference half cell is changed: cell potentials ___ change
DON’T
steps for determine potentials when reference cell is changed: CELL POTENTIAL
1) can still use hydrogen as régence electrode (so values in table DON’T change)
2) use standard cell formula to solve
steps for determine potentials when reference cell is changed: REDUCTION POTENTIAL
1) identify new reference half cell and write out half reaction
2) subtract/ add appropriate # to make sure E of reference cell is 0
3) write out half reactions of other
4) do the same thing you did to the E of the reference cell to the E of the other
what is a battery
more than one cell connected together in a series
what is a primary battery
disposable battery
what is a secondary battery
rechargeable battery
what is a fuel cell
a type of cell that can be refuelled
what type of reactions are fuel cells
spontaneous
steps for determine half reactions in hydrogen fuel cells
1) determine anode and cathode (if not given)
- can figure out through electron flow (anode to cathode)
2) write out oxi half reaction
- oxi occurs at anode
3) write out red half reaction
- red occurs at cathode
two sources of hydrogen gas
- fossil fuels
- use of electricity to break apart compounds
what is corrosion
spontaneous reaction which occurs between compounds and their environment
example of good corrosion and why
oxidization of copper
-copper oxide compound acts as a protective barrier for the copper beneath the surface
what is rust
the product of iron corrosion
what are the oxi and red half reactions of rust
oxi: Fe(s)—->Fe 2+ (aq) + 2e
red: O2(g) + 2H20(l) + 4e ——> 4OH-(aq)
what is galvanizing
protective layer of zinc is placed over the iron
what is a sacrificial anode
material that is oxidized in order to prevent another material from being oxidized
what is allowed to be a sacrificial anode for something
can be any stronger reducing agent than the material it has to protect
cathodic protection
more reactive metal is placed over but doesn’t completely cover vulnerable metal
replaced when oxidized
what is an electrolytic cell
a cell in which energy is used to power a NS reaction
electrolytic cells don’t have a _____
salt bridge
what is electrolysis
the NS splitting of a compound into its elements through the use of electric current
when does the chlorine anomaly occur
during the electrolysis of solutions containing chloride ions and water as the SOA’s
what happened during the chlorine anomaly
chlorine ions are oxidized (even though table shows water to be the SRA
secondary cells
rechargeable
example of a secondary cell
car battery
how do car batteries work
battery is acting as a voltaic cell when you start it (producing electricity from chemical POTENTIAL energy)
battery is acting as an electrolytic cell when you run in (electricity is being converted into chemical POTENTIAL energy)
what is electroplating
process in which metal ions are reduced using an electric current to coat an electrode
what is Faraday’s law
the amount of substance produced or consumed in electrolysis is proportional to charge flowing through circuit
