University:
Memorial University of Newfoundland
Course:
CHEM1050 | Laboratory
Academic year:

2020
Views:

307

Pages:

2
Author:

H. Mcqueen

Solution Form Cell with Non-Reacting Electrodes (Inert/Inactive) 1. Conditions on the Cathode At the cathode, a reduction reaction occurs, for this there is competition between cations or water. For cations that have a greater reduction potential than water, this means that the cation is being reduced. Meanwhile, if the cation reduction potential is smaller than that of water, then H2O has the right to be reduced. For this we have to know the position of H2O in the voltaic series. The position of H2O in the voltaic series is between Mn and Zn. ... Ca Na Mg A1 Mn H2O Zn Fe Ni Sn .... which is reduced by H2O which is reduced by the cation It turns out that most of the metals to the left of H2O are main group metals (group A), except for Mn metal. Meanwhile, the metals to the right of H2 O are transition group metals (group B), except H. Simply: The main group, which is reduced H2O. 2 H2 O(l) + 2 e– 2 OH– (aq) + H2 (g) Cathode: Cation Transition group, which is reduced by the cation. For example: Fe3+(aq) + 3 e– Fe(s) Ni2+(aq) + 2 e– Ni(s) 2. Provisions on Anode At the anode, an oxidation reaction occurs, for this there is competition between anions and water. Ideally, for anions with a small reduction potential or with a large oxidation potential, the anion is oxidized. Meanwhile, for anions with a large reduction potential or small oxidation potential, H2O is oxidized. It's just that most of the reduction potential sequences that are easy to remember are cations, not anions. To make it easier to remember, we see that there are 2 groups of anions, namely anions that contain O, such as SO, NO3 , C1O4 - so what is oxidized H2 O. This is because these anions are difficult to oxidize (Remember, the oxygen dexigant oxidation reaction). This means that this anion has maximum binding to the O atom so that it can no longer be oxidized. The S oxidation state in SO4 - the N oxidation state in NO3 , or the Cl oxidation state in C1O4 is already the largest oxidation state, so the oxidation state cannot change (it cannot carry out oxidation). Meanwhile, anions that do not contain O, such as Cl–, OH– , Br, are those that are oxidized. Simply: Contains O (,NO3–, C1O4–), oxidized H2O. H2O(l) 4 H+(aq) + O2(g) + 4 e– Anode: Anion Not contains O (Cl–, Br–, I–, H–), oxidized by anions. Contoh: 2 Cl–(aq) Cl2(aq) + 2 e– 4 OH–(aq) 2 H2O(l) + O2(g) + 4 e– Solution Form Cell with Reacting Electrodes (Active Electrodes) The electrode that reacts is a non-platinum or carbon electrode.These electrodes include copper (Cu), silver (Ag), nickel (Ni), iron (Fe), and others.Most electrodes are metal, thus the electrode influences the oxidation reaction at the anode. So the only electrode that reacts is at the anode. Meanwhile, at the cathode, the electrode will not react. Terms of this cell: Cathode: Like the provision of cations in a solution with an electrode that does not react. Anode: The electrode is oxidized, any anions are not considered.

New Documents from this Course

Corrosion - Study Notes

Memorial University of Newfoundland CHEM1050 | Laboratory

Lecture Note

Description

Related Documents

Free up your schedule!

Take 5 seconds to unlock