Student and teacher narratives on chemistry
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 SO42-,
NO3-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?
what js difference betwen learning resources and theaching material?
BalasHapusLearning resources are everything that can lead to learning. Something that can be shaped objects, data, facts, ideas, people and so forth. While the teaching materials are all materials such as information, text systematically arranged, which displays the whole figure of the competence that will be mastered learners and used in the learning process with the aim for planning and review of learning implementation
HapusCam you explain about 5 scientific approach?
BalasHapus1. observe
Hapus2. ask questions
3. reasoning
4. try
5. Learning Network or Collaborative Learning
What is diffreent 5 scientific approach then problem solving?
BalasHapusA. Understand the problem
HapusThe problems faced must be formulated, carefully constrained. If not, his efforts will be in vain.
B. Collecting data
If the problem is clear, can be collected data / information / description - information required.
C. Formulate hypotheses
An interim answer, which may provide the completion and description of the information obtained, may arise a hopeful possibility that will lead to problem solving.
D. Assess the hypothesis
By thinking it can be expected the consequences of a hypothesis. If it turns out that this hypothesis will not give good results, then it starts again with the second step.
E. Conducting experiment / test hypothesis
If a hypothesis gives good hope, then it is tested through experiment. If successful, then the problem is solved. But if it does not work, it should come back from the second or third steps.
F. Conclude
Report on the overall troubleshooting procedure that ends with a conclusion. Here it is possible to introduce a principle or law. The ability to solve problems should be taught to the students, because scientific methods are useful for them to solve difficult problems. This method can in addition be used to solve problems in various fields of study, can also be used for solutions related to the needs of students in everyday life.
What makes a solvent to be inert?
BalasHapusBecause a good solvent has a criterion it must be non-reactive (inert) to the reaction conditions.
Hapushow do you do a noisy student at the time of learning?
BalasHapusBy walking in the classroom and interacting with all students.
HapusGive me an example of the material you describe?
BalasHapusMelt of NaCl salt
HapusKatoda (-) : 2 Na+(l) + 2 e– ——> 2 Na(s) ……………….. (1)
Anoda (+) : 2 Cl–(l) Cl2(g) + 2 e– ……………….. (2)
Reaksi sel : 2 Na+(l) + 2 Cl–(l) ——> 2 Na(s) + Cl2(g) ……………….. [(1) + (2)]