Narrative dialogue between students and teachers with five elements of a scientific approach

Narrative About Electrochemical Cells

In the afternoon the class XII IPA 4 suddenly tense, because the teacher suddenly gave an impromptu quiz but most students have not understood the material presented so as to cause a long silence

Teacher:     All students, don’t you understand about the electrolysis cell matter we have been learned today?

(All the students were silent)

Teacher:     Why are you just silent? I assume to have understood. Okay then we will test your understanding, if nobody wants to ask.

(The student is restless, until in the end, the student asks a question).

Student1:    Miss (raise his hand) I still do not quite understand.

Teacher:     Good, at least you will be stalling the test time for a while. What do you not understand about the material of electrolysis cell this time?

Student1:    I still find it difficult to understand the reactions that occur in Anode and Cathode when using a not-inert electrode?

Teacher:     Okay, so here we go. The electrolysis cell is the decomposition of an electrode by the presence of an electric current. When an electrolyte is electrolyzed, the electron breaks down into cation and anions. The use of electrodes is itself seen from what substances will be electrolyzed.

Student2:    Then what about the not-inert electrode Miss?

Teacher:    All right, nama. I will explain to you slowly so you can understand. About electrolysis cell is it clear??? Anton and the others ???

Student1:    I understand Mrs, so the electrolysis depends on the substance to be dissolved?

Teacher:     Great! if you already understand. The inert electrode is comprised of three, they are Pt, C, Au which cannot oxidize. So when it is electrolyzed using this electrode, the oxidizing agent is H₂0, provided that the reacting agent is reacted is the residual oxy acid.

Student3:    But Mrs, why only H₂0? then what about electrolysis of  MgCl₂ solution???

Teacher:     Hmmm, look like this. So why do we use H₂0, because that oxidized residue of oxyic acid for example SO₄^2-, NO^3-etc. And when the oxidized in anode is a single anion, for example, Cl^-, F^-, Br^- then it will undergo oxidation of the anion itself.

Student3:    Hmm so Mrs, we should also look at the use of the electrodes themselves when a substance is known?

Teacher:     Yes son, adding a little explanation of electrolysis, the electrolysis cell itself has three characteristics. the first one is the presence of electrolyte solution containing free ions. The second is the existence of two electrons in the cell electrolysis then the presence of an external electric current source, such as batteries that drain direct current

Student1:    What the meaning of the free ion Mrs?

Teacher:    So free ion is an ion that can give or receive electron so that electron can flow through solution.

Student1:    Thank you Mrs. Well, now I understand.

Teacher  : Okay if you understand then we will start the test of understanding test

Problem 1. A solution of Bacl2 is electrolysed using pt electrode then what substance will be formed in cathode and anode?

Problem 2. A molten Na2so4 is electrolysed using Au-electrode then write the equation of the dianode and cathode reaction?

Student 1   : Bacl2 solution using pt electrode

Cathode     : 2H2o + 2e -> H2 + 2OH-

Anode         : 2Cl- -> Cl2 + 2e

Melt Na2so4

Cathode     : 2H2o + 2e -> H2 + 2OH-

Anode        : 2H2o -> o2 + 4H ++ 4e

Student 2   : Bacl2 solution using pt electrode

Cathode     : 2H2o + 2e -> H2 + 2OH-

Anode        : 2Cl- -> Cl2 + 2e

Melt Na2so4

Cathode     : 2H2o + 2e -> H2 + 2OH-

Anode        : 2H2o -> o2 + 4H ++ 4e

Student 3   : Bacl2 solution using pt electrode

Cathode     : 2H2o + 2e -> H2 + 2OH-

Anode        : 2Cl- -> Cl2 + 2e

Melt Na2so4

Cathode     : 2H2o + 2e -> H2 + 2OH-

Anode        : 2H2o -> o2 + 4H ++ 4e

Teacher: your answers are all right, so Mrs thinks matter about electrolysis is done.

link video youtube: https://www.youtube.com/watch?v=iZezWv3eN-4&t=15s