how do i write this reaction in cell notation
I2(s) + 2MnO4-(aq) + 4H+(aq) → 2IO3-(aq) + 2Mn2+(aq) + 2H2O(l)
To write the given reaction in cell notation, you will need to break it down into its half-reactions. The half-reaction that takes place at the anode (oxidation) and the half-reaction at the cathode (reduction). Here's how you can do it step by step:
1. Identify the oxidation half-reaction: The species that undergoes oxidation loses electrons. In this case, I2 (s) loses two electrons to become IO3-(aq).
2. Write the oxidation half-reaction: The half-reaction for the oxidation process in this case would be:
I2 (s) → 2IO3-(aq) + 2e-
3. Identify the reduction half-reaction: The species that undergoes reduction gains electrons. In this case, MnO4-(aq) gains five electrons and becomes Mn2+(aq).
4. Write the reduction half-reaction: The half-reaction for the reduction process in this case would be:
2MnO4-(aq) + 4H+(aq) + 5e- → 2Mn2+(aq) + 2H2O(l)
5. Balance the half-reactions: It is important to ensure that the number of electrons lost in the oxidation half-reaction is equal to the number of electrons gained in the reduction half-reaction. In this case, the oxidation half-reaction requires two electrons and the reduction half-reaction produces five electrons. To balance the electrons, multiply the oxidation reaction by five and the reduction reaction by two:
5 x [I2 (s) → 2IO3-(aq) + 2e-]
2 x [2MnO4-(aq) + 4H+(aq) + 5e- → 2Mn2+(aq) + 2H2O(l)]
6. Write the overall reaction: Now that the half-reactions are balanced, we can write the overall reaction by combining the two half-reactions:
5I2 (s) + 10MnO4-(aq) + 20H+(aq) → 10IO3-(aq) + 10Mn2+(aq) + 10H2O(l)
7. Determine the cell notation: In cell notation, the anode half-reaction is always written on the left side, and the cathode half-reaction is on the right side, separated by two vertical lines representing the salt bridge or porous barrier. The anode half-reaction is written first, followed by the cathode half-reaction. The species and their respective states are also indicated:
Anode: 5I2(s) → 10IO3-(aq) + 10e-
Cathode: 10MnO4-(aq) + 20H+(aq) + 10e- → 10Mn2+(aq) + 10H2O(l)
Overall cell notation: 5I2(s) | [I-] || [MnO4- (aq), H+(aq)] | 10Mn2+(aq), 10H2O(l)