Chem Unit 11: Electrochemistry
electron trander reations are called redox
results in electricity (spontatnous) or can be imposed by putting in an electron current (non-spontatnous)
“electrochemistry”
originally called oxidation because a compound would bind with oxygen to make an oxide
reductions If it lost oxygen because it lost volume
Oxidation - loss the electrons, increase in oxidation number, increase in oxygen
Reduction - gain in electrons, lower oxidation number, decrease in oxygen, increase in hydrogen
Oxidizing Agent - is the electron acceptor, and is reduced, “helps oxidize”
Reducing Agent - electron doner, is oxidized, helps reduce
In a reaction, oxidation and reduction agent both have to be in the same equation
monoatomic ions - their charge
Hydrogen - +1 (when acts like a metal) or -1 (when acting like nonmetal)
Oxygen - always -2 except in peroxides where it is -1
Uncombined element or free element - is 0
Neutral Compound - the sum of the oxidation number is 0
Polyatomics - the sum of oxidation number is the charge of the poly atomics
Group 1 metals are +1, and group 2 are +2, flourine is always -1
electrochemical reactions are spontaneous (chemcial → electricity) or nonspontatnous (electric → chemical)
half reactions
voltaic/ galvanic cell
Direct redox reaction - oxidation and reduction in direct contact “same container”
Indriect Redox Reaction - occurs in different containers and the elctrons are transferred with a wire
reactions occur at the same time at different electrodes
reduction and oxidation occur in the cathode
separate into half reactions
balance the atoms
add h2o and H+ and e- to balance
cancel out the electrons
add together and cancel out
if basic add OH to the H+ on both studies
to check, check the charges and atoms
Anode - is negative and is the source of the electrons (electrode), the electrode will gain mass
Cathode. - is positive and is the sink for electrons (electrode), the electrode will turn into the solution
Electrons move through a wire
salt bridge is to balance the charges and maintain the efficiency
Product Favroed reaction
Dry Cell Battery:
The anode is usually Zn (reduction agent, oxidized, electron donator). Zn Case
The Cathode is usually NH4+
conductor is Graphite
Porous Seperator
Paste
Alkaline Battery
under basic conditions
anode is Zn
cathode is MnO2
Mercury Battery
under basic conditions
anode is Zn
cathode is HgO
Lead Storage Battery
acidic
large batteries in cars
Anode is Lead Grids
Cathode is Spongy Led
Ni-Cad Batteruy
Rechargable and basic
anode is Cd
Cathode is NiO
Li-Ion Battery
anode is LiC6
Cathode is CoO2
H2 Fuel
H2 is oxidized
O2 is reduced
Standard Cell Potential Eo - is the quantitative measure of the tendency of reactnats to proceed to products when all are at their standard states
Calculating using the Standard Reduction Potentials
if we know the E of each half reaction we could get the net E
E = E(of the reduced more positive) - (oxididized E)
more positive value is what is being reduced’
From Table vs As written
if its as written then the reaction has to be organized as so and the equation may result in a negative voltage which means its non spontaneous
the reatants are favored
electric current used to make a chemical change
the E is negative
electrochemical energy is used to bring a chemical change
nonsponatnous reactions
oxidation is anode, reduction is at cathode but the symbols are reversed
Examples:
water → H and O
gold plating
oxygen is very reactive
electron transfer → redox
Effects:
corrosion
Metal Atoms give their electorns to oxygen “electronegative:”
Iron → Iron Oxide (Rust)
Copper → Copper Oxide (green protective layer) Blocks out moisture and oxygen
Aluminum → aluminum oxide
Paint to prevent oxidation
External conditions can make increase oxidation rate
raising temperature
presence of calcium
in salt water “can conduct electrons”
Uses:
Zinc metal in copper solution → copper plating
batteries:
have bridge or connected by a porous barrier
Lithum cell -
was light and very reactive “lots of volts”
good for pace makers
litherum anode - magenese cathode
has a membrane to allow ions through “salt brige”
Lead Battery
used for cars
Several Cells
Led and Led Dioxide in sulfuvic acid
Electrloylsis
electricity used to do nonsponatnous reactions
to plate metals
can separate water into hydrogen gas and oxygen
used for solar power
removing rust
Electrochemistry: the transfer of electrons and can power batteries = needs metals
redox: one gains and another loses electrons
Redox Reactions in the Body
require trace metals
B12 B9 - essential to prevent heart disease and birth defects
Oxidation loses electrons, reduction gains electrons
Transition Metals - can have many different charges and this changes the oxidation numbers
Redox in a single solution
A zinc metal put into a copper ion solution
since a copper ion is higher up on the recution table, the zinc will give up its electrons and makes the copper a solid
zinc will disolve because it is oxidized (recution agent)
Batteries:
Redox Reactions are spontaneous
Movement of electrons make a voltage
betteires use 2 different hald reactions
the wire is where the electorns transfer and this energy is harvested
electrodes are connected
salt bridge: to balance the charges that are created NaCl
volt meter (shows the pressure)
Redox in Body:
transforming food into energy
Vitamins have trace metals and are molecules found in food
B12 methionine - is found in meat and fish and B9 folate- prevents heart disease and promote cell division (mitosis)
has cobalt and has oxidation +1, 2, 3
The number of electrons gained or lost is determined by the oxidation number
anaerobic chamber - used to study
oxidation numbers change how vitamins react
co+1 - allows folic acid usage - cell replication
co+3 - helps make methionine amino acid
folic acid is B9 - and reacts with B12 cobalt
Vitamin B2 makes the cobalt from +2 to +1 which is more useful
Spontanous - will just happen
Non spontaneous - needs energy to happen - “electrolytic”
-bleaching hair - redox - hydrogen peroxide and melanin, melanin is oxidized
electron trander reations are called redox
results in electricity (spontatnous) or can be imposed by putting in an electron current (non-spontatnous)
“electrochemistry”
originally called oxidation because a compound would bind with oxygen to make an oxide
reductions If it lost oxygen because it lost volume
Oxidation - loss the electrons, increase in oxidation number, increase in oxygen
Reduction - gain in electrons, lower oxidation number, decrease in oxygen, increase in hydrogen
Oxidizing Agent - is the electron acceptor, and is reduced, “helps oxidize”
Reducing Agent - electron doner, is oxidized, helps reduce
In a reaction, oxidation and reduction agent both have to be in the same equation
monoatomic ions - their charge
Hydrogen - +1 (when acts like a metal) or -1 (when acting like nonmetal)
Oxygen - always -2 except in peroxides where it is -1
Uncombined element or free element - is 0
Neutral Compound - the sum of the oxidation number is 0
Polyatomics - the sum of oxidation number is the charge of the poly atomics
Group 1 metals are +1, and group 2 are +2, flourine is always -1
electrochemical reactions are spontaneous (chemcial → electricity) or nonspontatnous (electric → chemical)
half reactions
voltaic/ galvanic cell
Direct redox reaction - oxidation and reduction in direct contact “same container”
Indriect Redox Reaction - occurs in different containers and the elctrons are transferred with a wire
reactions occur at the same time at different electrodes
reduction and oxidation occur in the cathode
separate into half reactions
balance the atoms
add h2o and H+ and e- to balance
cancel out the electrons
add together and cancel out
if basic add OH to the H+ on both studies
to check, check the charges and atoms
Anode - is negative and is the source of the electrons (electrode), the electrode will gain mass
Cathode. - is positive and is the sink for electrons (electrode), the electrode will turn into the solution
Electrons move through a wire
salt bridge is to balance the charges and maintain the efficiency
Product Favroed reaction
Dry Cell Battery:
The anode is usually Zn (reduction agent, oxidized, electron donator). Zn Case
The Cathode is usually NH4+
conductor is Graphite
Porous Seperator
Paste
Alkaline Battery
under basic conditions
anode is Zn
cathode is MnO2
Mercury Battery
under basic conditions
anode is Zn
cathode is HgO
Lead Storage Battery
acidic
large batteries in cars
Anode is Lead Grids
Cathode is Spongy Led
Ni-Cad Batteruy
Rechargable and basic
anode is Cd
Cathode is NiO
Li-Ion Battery
anode is LiC6
Cathode is CoO2
H2 Fuel
H2 is oxidized
O2 is reduced
Standard Cell Potential Eo - is the quantitative measure of the tendency of reactnats to proceed to products when all are at their standard states
Calculating using the Standard Reduction Potentials
if we know the E of each half reaction we could get the net E
E = E(of the reduced more positive) - (oxididized E)
more positive value is what is being reduced’
From Table vs As written
if its as written then the reaction has to be organized as so and the equation may result in a negative voltage which means its non spontaneous
the reatants are favored
electric current used to make a chemical change
the E is negative
electrochemical energy is used to bring a chemical change
nonsponatnous reactions
oxidation is anode, reduction is at cathode but the symbols are reversed
Examples:
water → H and O
gold plating
oxygen is very reactive
electron transfer → redox
Effects:
corrosion
Metal Atoms give their electorns to oxygen “electronegative:”
Iron → Iron Oxide (Rust)
Copper → Copper Oxide (green protective layer) Blocks out moisture and oxygen
Aluminum → aluminum oxide
Paint to prevent oxidation
External conditions can make increase oxidation rate
raising temperature
presence of calcium
in salt water “can conduct electrons”
Uses:
Zinc metal in copper solution → copper plating
batteries:
have bridge or connected by a porous barrier
Lithum cell -
was light and very reactive “lots of volts”
good for pace makers
litherum anode - magenese cathode
has a membrane to allow ions through “salt brige”
Lead Battery
used for cars
Several Cells
Led and Led Dioxide in sulfuvic acid
Electrloylsis
electricity used to do nonsponatnous reactions
to plate metals
can separate water into hydrogen gas and oxygen
used for solar power
removing rust
Electrochemistry: the transfer of electrons and can power batteries = needs metals
redox: one gains and another loses electrons
Redox Reactions in the Body
require trace metals
B12 B9 - essential to prevent heart disease and birth defects
Oxidation loses electrons, reduction gains electrons
Transition Metals - can have many different charges and this changes the oxidation numbers
Redox in a single solution
A zinc metal put into a copper ion solution
since a copper ion is higher up on the recution table, the zinc will give up its electrons and makes the copper a solid
zinc will disolve because it is oxidized (recution agent)
Batteries:
Redox Reactions are spontaneous
Movement of electrons make a voltage
betteires use 2 different hald reactions
the wire is where the electorns transfer and this energy is harvested
electrodes are connected
salt bridge: to balance the charges that are created NaCl
volt meter (shows the pressure)
Redox in Body:
transforming food into energy
Vitamins have trace metals and are molecules found in food
B12 methionine - is found in meat and fish and B9 folate- prevents heart disease and promote cell division (mitosis)
has cobalt and has oxidation +1, 2, 3
The number of electrons gained or lost is determined by the oxidation number
anaerobic chamber - used to study
oxidation numbers change how vitamins react
co+1 - allows folic acid usage - cell replication
co+3 - helps make methionine amino acid
folic acid is B9 - and reacts with B12 cobalt
Vitamin B2 makes the cobalt from +2 to +1 which is more useful
Spontanous - will just happen
Non spontaneous - needs energy to happen - “electrolytic”
-bleaching hair - redox - hydrogen peroxide and melanin, melanin is oxidized