Redox & Batteries Worksheet
Give the complete redox equations for the following:
Fe + H2O2 -> Fe(OH)3
H2SO4 + Al -> Al2(SO3)3 + H2O
How are electrolytic and voltaic cells similar?
How are electrolytic and voltaic cells different?
Which type of cell is involved in electroplating?
Use the following data to find the redox equations for the battery, the voltage of the battery, and which metal
will be the cathode and anode.
Li & H
Cu & Cr
Pb & Cr
Redox & Batteries Worksheet
Give the complete redox equations for the following:
Fe + H2O2 -> Fe(OH)3
Step 1 – ionic equation
Fe + H2O2 -> Fe+3 + 3OH-1
Step 2 – oxidation numbers
Fe0 + H+12O-12 -> Fe+3 + 3O-2H+1
Step 3 – identify what changed
Fe0 + H+12O-12 -> Fe+3 + 3O-2H+1
Step 4 – write simple half reactions
Fe0 -> Fe+3 + 3eO-1 + e -> O-2
Step 5 – balance # of electrons
Fe0 -> Fe+3 + 3e3O-1 + 3e -> 3O-2
Step 6 – check against ionic equation – are all parts available?
Fe0 and Fe+3 are in the ionic equation, so it is all set
3O-1 and 3O-2 are not in the ionic equation, so we need to substitute the correct materials
3H2O2 + 6e -> 6OH substituting H2O2 for O-1 gives 6 O, therefore we need 6 electrons
Step 7 – label as red or ox
Ox
2Fe0 -> 2Fe+3 + 6eRed 3 H2O2 + 6e -> 6OH
H2SO4 + Al -> Al2(SO3)3 + H2O
2H+ + SO4-2 + Al -> 2Al+3 + 3SO3-2 + H2O
2H+ + S+6O-24-2 + Al0 -> 2Al+3 + 3S+4O-23-2 + H+12O-2
Al0 -> Al+3 + 3eS+6 + 2e -> S+4
2Al0 -> 2Al+3 + 6e3S+6 + 6e -> 3S+4
6H+ + 3SO4 + 6e- -> 3SO3 + 3H2O
Ox
Red
Al0 -> Al+3 + 3e6H+ + 3SO4 + 6e- -> 3SO3 + 3H2O
How are electrolytic and voltaic cells similar?
They are both redox reactions directly involved with movement of electrons
How are electrolytic and voltaic cells different?
Voltaic cells push electricity out, creating current (a battery)
Electrolytic cells require an outside push of current to work (a battery charger)
Which type of cell is involved in electroplating?
Electrolytic cell
Use the following data to find the redox equations for the battery, the voltage of the battery, and which metal
will be the cathode and anode.
Li & H
From the table (pg 615)
Li+ + e- -> Li
-3.04v
2H+ + 2e- -> H2
0.00v
3.04v
0.00v
2Li+ + 2e- <-> 2Li -3.04v
2H+ + 2e- <-> H2 0.00v
anode
cathode
2Li -> 2Li+ + 2e2H+ + 2e- -> H2
Cu & Cr
From the table (pg 615)
Cu+2 + 2e- -> Cu
Cr+3 + 3e- -> Cr
3.04v
0.00v
+3.04v
+0.34v
-0.74v
-0.34v
+0.74v
3Cu+2 + 6e-<-> 3Cu
2Cr+3 + 6e- <-> 2Cr
+0.34v
-0.74v
anode
cathode
2Cr ->2Cr+3 + 6e3Cu+2 + 6e--> 3Cu
+0.74v
+0.34v
+1.08v
Pb & Cr
From the table (pg 615)
Pb+2 + 2e- -> Pb
Cr+3 + 3e- -> Cr
+0.34v
-0.13v
+0.13v
+0.74v
3Pb+2 + 6e- -> 3Pb
2Cr+3 + 6e- <-> 2Cr
-0.13v
-0.74v
anode
cathode
2Cr ->2Cr+3 + 6e3Pb+2 + 6e- -> 3Pb
+0.74v
-0.13v
+0.61v