The application of a scientific approach will be the challenge of teachers through the development of 7 activities of students that is observing, asking, trying, processing, tasting, reasoning, and creating.

The Dialogue:
 On thursday morning chemistry class prepare the references to study about acid,base and the pH
before the the teacher comes.
*teacher enter the class*

Teacher : Good morning everybody, in this morning we will discuss about acid and bases and pH . So who know the Defenition of Acid And Bases?

Student : *hand’s up* I know sir

Teacher : Yes, please

Student : Acids are ionic compounds that produce positively charged hydrogen ions (H+)  when dissolved in water. Acids taste sour and react with metals. Bases are ionic compounds that produce negatively charged hydroxide ions (OH-) when dissolved in water. Bases taste bitter and do not react with metals. Examples of acids are vinegar and battery acid. The acid in vinegar is weak enough to safely eat on a salad. The acid in a car battery is strong enough to eat through skin. Examples of bases include those in antacid tablets and drain cleaner. Bases in antacid tablets are weak enough to take for an upset stomach. Bases in drain cleaner are strong enough to cause serious burns.

Teacher : Ok, that’s good. So Acids are ionic compounds that produce positively charged hydrogen ions (H+) when dissolved in water. Acids taste sour and react with metals. Bases are ionic compounds that produce negatively charged hydroxide ions (OH-) when dissolved in water.Understand?

Student : *hand’s up* sir, What do you think causes these differences in the strength of acids and bases?
Teacher : The strength of an acid or a base depends on how much of it breaks down into ions when it dissolves in water
 
Student : *hand’s up* What determines how acidic or basic a solution is??

Teacher : Acidic solutions have a high concentration of H+, and those that are basic will have a low H+ concentration and a higher OH- concentration.Thus the higher the concetration of protons, the lower the ph will be. The same is true for alkaline solutions which have a high ph. Any other questions?

Student : What is pH? What is the pH of a neutral substance?

Teacher : The strength of acids and bases is measured on a scale called the pH scale. By definition, pH represents the acidity, or hydrogen ion (H+) concentration, of a solution. Pure water, which is neutral, has a pH of 7. With a higher the concentration of hydrogen ions, a solution is more acidic and has a lower pH. Acids have a pH less than 7, and the strongest acids have a pH close to zero. Bases have a pH greater than 7, and the strongest bases have a pH close to 14. Got it?

Student : How much more acidic is a solution with a pH of 4 than a solution with a pH of 7??

Teacher : A solution with a pH of 4 is 1000 (10 × 10 × 10, or 103) times more acidic than a solution with a pH of 7..

Student : *hand’s up* Why is the pH of the environment important for living things??

Teacher : Acidity is an important factor for living things. For example, many plants grow best in soil that has a pH between 6 and 7. Fish may also need a pH between 6 and 7. Certain air pollutants form acids when dissolved in water droplets in the air. This results in acid fog and acid rain, which may have a pH of 4 or even lower
*the bells are ringing*
Teacher : Ok, I think It’s enough for today. See you on the next lesson and don’t forget to prepare the references about Rate of law for next week.

All of students : Ok sir!