Script of teacher and students dialogue

            At 09.30 AM The bell rang time for Ms. Nur to enter the class X IPA4

Ms. Nur : Morning all. How are you?

All students: Morning Miss, i'm fine.

Ms. Nur : Today we will learn about acids and bases. Does anyone know what is acid?

Dina : Me miss, I think acid is a compound and have a pH < 7.

Ms. Nur : Yes, that's right Dina. Then there is another bases, does anyone know what is a base?

Ayu : Me miss, I think the base is a compound and have a pH > 7.

Ms. Nur : Yes, it is true what is delivered ayu. Well, the theory of acids and bases that we will study there are three, theory according to Arrhenius, Bronsted-Lowry, and Lewis. According to the theory of Arrhenius acid is a substance which if dissolved in water will produce H⁺ ions, whereas a base is a substance that if dissolved in water produces OHˉ ion.

Lusi: Miss, Iam very compused how if the solution is not dissolved into the water?

Ms. Nur : Good Lusi. Not all compounds dissolve in water, then the acid-base theory is then fixed by Bronsted-lowry. Anyone can help me, to explain the theory of acidic bases according to Bronsted-Lowry?

Dinda : Me Miss, according to this book I read, acid according to Bronsted-Lowry is a substance that can give proton (H⁺) to other substance or proton donor. While a base is a substance that receives protons (H⁺) from another substance that is a proton acceptor.

Ms. Nur : yes, excellent Dinda. Well, according to this theory the acid gives the proton (H⁺) and the base receives the proton (H⁺). For example when the solution of H₂O is dissolved in H₂O produces H₃O⁺ and OHˉ. Therefore,H₂O is an acid because it gives one proton to H₃O⁺ . and H₂O is base because it receives one proton from OHˉ. This is the strength of the Bronsted-Lowry acid-base theory that can explain any reaction that occurs in any form, including gases, non-aqueous solutions, aqueous solutions, and heterogeneous mixtures.

Dinda : Oh, so there is another theory yes Miss. So it can be concluded that the acid according to Bronsted-Lowry is a proton donor, whereas a base is a proton acceptor. Thank you Miss I already understand it.

Ardi : Miss then what if the substance does not happen the handover of protons?

Ms. Nur : It is okay to answer that question then you will explain the third acid-base theory that is Lewis. According to Lewis a substance can include acids if it can accept electron pairs while a base if the substance is capable of giving electrons. With the existence of Lewis acid theory is able to explain the ractions that do not involve the handover of protons. For example CaO is reacted with SO2 to produce CaSO3, Oˉ² of CaO has 2 free electron pairs that react with 2 hands in SO2. Then Oˉ² is a Lewis base while SO2 is a lewis acid. The covalent bond formed is the O - S bond

Mima : I wants to ask whether the advantages of the Lewis acid-base theory compare to others?

Ms. Nur : Thank you Mima for your question. As you have already explained, Lewis acid-base theory is able to explain acid-base reactions that do not involve the transfer of protons. In addition, Lewis acid-base theory is able to explain the acid-base reaction, either in water solvents, non-water solvents, or without solvents. How Mima, already understand?

Mima : Thanks Miss for the answer.

Ms. Nur : Well then to know a substance including acid or base used indicator to measure it. And one of them is litmus paper. Approximately when the red litmus is put into the base solution what will happen?

Dzikri : I think when red litmus is inserted into base solution then it will change its color to be blue.

Ms. Nur : Yes good answer. That litmus paper is inserted into base then it will convert litmus to red. Then what would happen if the blue lakmus was inserted in the acid solution?

Wahyu : I think when the blue lakmus is inserted in the acid solution it will change the blue litmus color to red.

Ms. Nur : Good answer Wahyu. If the blue lakmus is inserted in the acid solution then there will be a change in the blue litmus to red.

            At 11.30 AM The break bell rang

Ms. Nur : Well all the material I can deliver. Hopefully your can be understood and learn again at home. And Good day.

All the students: Good day Miss...