Sulfuric acid/ Lead Battery:
-the electrodes for the battery are composed of Pb(s), PbO2, and/or PbSO4. What are the half reaction occuring at each electrode? include electrolysis of water:
Process Anode/Cathode
Initial Charging:
Discharging
Recharging
Surely you don't want me to give you all the answers. Perhaps you just need a hint or two. Tell me what you don't understand about the next step if you get stuck.
The battery in its fully charged state is Pb is one pole and PbO2 is the other. Pb is oxidized to Pb^+2 where it reacts with the H2SO4 to form PbSO4.
The other pole is PbO2 and it is reduced to Pb^+2 where it reacts with H2SO4 to form PbSO4. At its fully discharged state, both electrodes are PbSO4. This should get you started.
1)I know that initially charging, PbO2 is transferring e- to Pb. So when I charge lead electrodes with Battery, am I sending proton to the lead and receiving back the e-? so Pb is the battery?
since Pb is accepting e-, it's being oxidized [anode] PbO2 is donating e-, so being reduced [cathode]
2)for discharging: Pb is transferring e- to PbO2. Pb is cathode and PbO2 is anode?
3) recharging: does this process involve sulfuric acid? why are we using sulfuric acid???
THANKS
For a battery that is fully charged and you are using it (discharging it),
Pb + H2SO4 ==> PbSO4 + 2e + 2H^+
PbO2 + 2H2SO4 2e ==> PbSO4 + 2H2O + SO4^=
Remember that oxidation is the loss of electrons and reduction is the gain of electrons. For discharging, Pb is the anode and negatively charged while PbO2 is the cathode and is + charged.
H2SO4 is the electrolyte .
To determine the half-reactions occurring at each electrode for a sulfuric acid/lead battery, we need to understand the processes involved during the initial charging, discharging, and recharging of the battery. These processes involve the electrolysis of water and the reactions at the electrode surfaces.
1. Initial Charging:
During the initial charging of a lead-acid battery, electrical energy is supplied to convert the reactants on the electrodes into their charged forms. The anode (negative electrode) is typically composed of lead (Pb), and the cathode (positive electrode) consists of lead dioxide (PbO2). The electrolyte in the battery is a dilute sulfuric acid (H2SO4) solution.
- At the anode:
The half-reaction occurring at the anode during the initial charging is the oxidation of lead. The chemical equation is as follows:
Pb(s) -> Pb2+(aq) + 2e-
In this reaction, solid lead (Pb) is converted into aqueous lead ions (Pb2+) and releases two electrons (2e-).
- At the cathode:
The half-reaction occurring at the cathode during the initial charging is the reduction of lead dioxide. The chemical equation is as follows:
PbO2(s) + 4H+(aq) + SO4^2-(aq) + 2e- -> PbSO4(s) + 2H2O(l)
In this reaction, lead dioxide (PbO2) reacts with hydrogen ions (H+) from the sulfuric acid solution, sulfate ions (SO4^2-), and gains two electrons (2e-) to form lead sulfate (PbSO4) and water (H2O).
2. Discharging:
During the discharging process, the battery delivers electrical energy by converting the stored chemical energy back into electrical energy.
- At the anode:
The half-reaction occurring at the anode during discharging is the reverse of the initial charging reaction. The chemical equation is as follows:
Pb2+(aq) + 2e- -> Pb(s)
In this reaction, lead ions (Pb2+) from the lead sulfate (PbSO4) at the anode gain two electrons (2e-) and are reduced back to solid lead (Pb).
- At the cathode:
The half-reaction occurring at the cathode during discharging is the reverse of the initial charging reaction. The chemical equation is as follows:
PbSO4(s) + 2H2O(l) -> PbO2(s) + 4H+(aq) + SO4^2-(aq) + 2e-
In this reaction, lead sulfate (PbSO4) at the cathode reacts with water (H2O) and releases two electrons (2e-) to reform lead dioxide (PbO2), hydrogen ions (H+), and sulfate ions (SO4^2-).
3. Recharging:
During the recharging process, the battery is connected to an external electric source, supplying energy to reverse the discharging reactions and restore the reactants on the electrodes.
- At the anode:
The half-reaction occurring at the anode during recharging is the same as the initial charging reaction because the battery is being charged again. The chemical equation remains:
Pb(s) -> Pb2+(aq) + 2e-
- At the cathode:
The half-reaction occurring at the cathode during recharging is the same as the initial charging reaction. The chemical equation remains:
PbO2(s) + 4H+(aq) + SO4^2-(aq) + 2e- -> PbSO4(s) + 2H2O(l)
These are the half-reactions occurring at each electrode during the initial charging, discharging, and recharging processes in a sulfuric acid/lead battery, including the electrolysis of water.