I'm doing a redox potential/lead acid cell experiment and one of the questions that were asked was:
-What were the identities of the gases you saw being produced at the + and - electrodes during the cell conditioning process?
We used H2SO4
How do I go about answering this, I don't know what gases were produced, other than I knew something was produced. I can't find the answer in my textbook or lab manual. Help me!
The lead/acid cell is
PbO2 + H2SO4 ==> PbSO4 + 2H2O
I assume you mean by conditioning that you are charging the cell from scratch. So the water is electrolyzed and you would expect H2 gas to be formed at the - electrode and O2 gas to be formed at the + electrode.
To determine the identities of the gases produced at the + and - electrodes during the cell conditioning process in your redox potential/lead-acid cell experiment, you will need to rely on the knowledge of electrochemistry and the chemical reactions occurring at each electrode.
Since you mentioned that H2SO4 was used in the experiment, it provides a clue as to what gases could be produced.
Here's how you can approach finding the answer:
1. Understand the redox reactions involved: In a lead-acid cell, the main reactions occurring involve the oxidation of lead at the anode (+ electrode) and the reduction of lead dioxide at the cathode (- electrode). It's important to know the chemical reactions happening at each electrode to determine the possible gases produced.
2. Analyze the anode reaction: At the anode, lead (Pb) is oxidized according to the following equation:
Pb(s) + H2SO4(aq) -> PbSO4(s) + 2H+(aq) + 2e-
Note that two protons (H+) are released as a byproduct.
3. Analyze the cathode reaction: At the cathode, lead dioxide (PbO2) is reduced according to the following equation:
PbO2(s) + H2SO4(aq) + 2H+(aq) + 2e- -> PbSO4(s) + 2H2O(l)
Here, water (H2O) is produced as a byproduct.
Based on these equations, you can conclude that the gas produced at the anode (+ electrode) is hydrogen (H2) due to the release of two protons (H+) in the anode reaction. At the cathode (- electrode), no gas is produced as the byproduct is water (H2O), which is in the liquid state.
Remember to carefully consider any other reactions or factors in your specific experiment that could affect the outcome.