Appendix A: Intervention Instructional Program on Acids and Bases

Appendix A: Intervention instructional program on acids and bases

Day 1: Administration of achievement test on acids and bases (Pretest)

Day Lesson Outline of lessons number 2 1 & 2 Topic: Characteristics of acids and bases Objectives of the lesson: 1. To investigate the characteristics of acids and bases. 2. To classify unknown liquids as acidic, basic or neutral, based on their characteristics. Phase 1. Introduction Students are shown a concept map and explained what they are going to learn in this lesson. Then, they are shown a lemon, vinegar and soap as examples of substances containing acids and bases which can be found in daily life, followed by questions such as:  What type of flavor does a lemon have?  Why does the lemon taste like that?  How would you feel if (a) this lemon came in contact with broken or sore skin? (b) you were to eat a lemon when you have a sore in your mouth?  What do you feel when you wash your hands using soap?  Have you accidentally tasted soap foam when taking a bath? Safety Issue Explain that the acids found in foods are very dilute acids and do not harm the skin. However, many acids found in the chemistry lab are very concentrated and can cause severe burns if they come into contact with the skin. Dilute bases do feel slippery when applied to the skin, but concentrated bases, like concentrated acids, can cause burns if they come in contact with the skin. Remind students that they should never taste or touch chemicals in the laboratory. Phase 2. Hands-on Activity Show the students three beakers which contain unknown, colourless liquids labelled A, B and C (containing solutions of HCl, NaOH, and tap water). Ask the questions:  How could you find out whether these liquids were acidic, basic or neutral? Introduce the terminology of indicator to students such as litmus, universal indicator, BTB (bromothymolblue), methyl orange. Ask another key question:

1  Another way to identify acids or bases is their reactions with metals such as magnesium or zinc. How will you decide if an acidic solution or basic solution reacts with a metal? Direct students to the hands-on activity: identification and grouping of liquids as acidic, basic or neutral solutions. Directions for students in worksheet: You are provided with three liquids labeled A, B and C. Determine whether the liquids are acids, bases or neutral using BTB indicator or litmus and their reactions with magnesium (Mg) and calcium carbonate. Then, classify them into acid and base or neutral liquids. Before conducting the activities, students have to plan their investigations using the worksheet provided by discussing first with their own group. After the discussion, students in each group should show their plan to the teacher. If it is approved then students can conduct their investigation. Phase 3. Class Discussion Students discuss their results in groups and present to the class. The teacher guides discussions. After presentations and discussions confirm that solution A is acidic, solution B is basic, and solution C is neutral. Request students to write the relevant chemical equations. Lead students to make conclusion about what they have learned about the characteristics of acids and bases. Phase 4. Application (This activity will be conducted by students in the next lesson). Inform students that they are going to test some common household substances that they want to test using BTB or litmus and conduct experiments the following day, so they have to bring their own materials/liquids.

3 3 This activity is the application (Phase 4) of characteristics of acids and bases. Students conduct an investigation using their own materials/liquids and using skills they have learned from the previous lesson. Stage I, II, III and IV will take place again here. Objective of the lesson 1. To identify common households or liquids around students’ house as acids, bases, or neutral. Phase 1. Introduction Show to the students the concept map and connect what they have learned

2 previously to today’s lesson. Ask key questions:  How do you know that your materials/liquids you bring to the laboratory are acidic, basic or neutral? Phase 2. Hands-on activity The learning steps are similar to the previous activities in which in their own group, they have to plan an investigation, to implement the investigation after consulting to teacher and to conclude the result of their investigation. Phase 3. Class discussion Students report their investigations in front of the class. Phase 4. Application Give students other examples of materials /liquids they found in daily life beyond students’ materials/liquids and ask them to predict whether they are acids, bases or neutral.

4 4 & 5 In this lesson, students do not conduct the investigation in laboratory. The main activity here is discussion in their own group using the worksheet provided. Topic: Definition of acids and bases and neutralization Objectives of the lesson: 1. To define acid and base according to Arrhenius’ theory. 2. To describe the process of neutralization and the product of neutralization. 3. To write neutralization equations, given certain acids and bases. First, show the students the concept map and let them know which topic they are going to study for today’s lesson. Then, show some acids and bases to students and pose questions:  From two groups of acids and bases, can you see the similarity of the solutions of each group?  Can you write down the equation of each solution in water?  Can you define what an acid and a base are by referring to the equations? Ask students to discuss their worksheet in their own group and to conclude what is acid and base in their own words. After that, invite students to present and discuss with the whole class. Emphasize the Arrhenius theory of acid and base. Provide students one example of the neutralization process in the context of daily life using antacid medicine. Ask question:  Why do you think that some people who have stomachaches take antacids to relieve the symtoms? Demonstrate using solutions of HCl, NaOH, NaCl and water using Predict- Observe-Explain technique.

3  Predict what happen if I drip BTB or dip universal indicator into an HCl solution?  Predict what happen if I drip BTB or dip universal indicator into a NaOH solution?  What happens if I mix the HCl solution and NaOH solution? Drip BTB to salt solution and ask students to explain what has happened.  What do you know about neutralization? Ask students to discuss in their own group and whole class about neutralization. Back to the questions about antacids. Let students discuss the neutralization process in the stomach and write the neutralization equation. NOTE:

An antacid contains a base such as Mg (OH)2 and the function of this base is to neutralize acid in your stomach when you have stomach ache/indigestion. The neutralization reaction:

Mg(OH)2 + 2 HCl MgCl2 + 2 H2O Give students another problem to discuss and write down their solution in the blackboard.  Write the reaction in which the sulfuric acid is neutralized by the base KOH. What is the formula of the salt formed in this process? Ask students to make conclusion about the concepts they just learned (acid and base according Arrhenius and neutralization).

5 6 & 7 Topic: Strength of acids and bases Objective of the lesson: To investigate the strength of acids and bases. Specific objectives: 1. Relate different electrical conductivities of acidic or basic solutions to their degree of dissociation or ionization. 2. Distinguish strong and weak acids or bases by their degree of dissociation or ionization. 3. Compare and contrast the composition of strong and weak solutions of acids or bases. 4. Relate pH to the strengths of acids and bases. Phase 1. Introduction Show the concept map and connect what students have learned from the new topic. Relate the new topic with household materials which contains weak and strong acids and bases. Ask key questions:  Which solution is stronger acid: 0.1 M HCl solution or 0.1M

CH3COOH solution?

4  Which solution is most acidic amongst 0.1M HCl solution; 0.001M

HCl solution; 0.1M CH3COOH solution and 0.001M CH3COOH solution? Phase 2. Hands-on activity Provide students with some solutions of HCl and CH3COOH with different concentrations and universal indicator. Before students plan their investigation in their group, teacher demonstrates how to use a simple conductivity meter. After consulting the teacher about their plan students conduct activity and discuss their result with their group members. Phase 3. Class Discussion Ask students to present their results of the investigation with the whole class, direct the discussion and ask students to make conclusions. Phase 4. Application Provide students some problem connected to strength of acids and bases, such as: (if the time is not available, the students will take these problems as their homeworks)  You test several solutions and find that they have pH values of 7.6, 9.8, 4.5, 2.3, 4.0, and 11.6. a. Which solution is the closest to being neutral? b. Which solution is the most basic solution?  Blood has a pH of 7.4 and an antacid, which contains base for upset stomach, has a pH of 10.4. What is the difference in pH between the two bases? Compare the hydroxide ion concentration of the two solutions. Day 6: Administration of: (1) Achievement test on acids and bases (Posttest) (2) Self-evaluation questionnaire on students’ perceptions of their competence and confidence in carrying out the inquiry activities (3) Open-ended questionnaire on students’ perceptions of the instructional process

Appendix B: Achievement test on acids and bases

1. The following pictures show some common materials that you may come across in and

around your home. Identify each picture and decide whether it falls in one of the categories:

acidic, basic, or neutral.

5 (20 marks)

1. Each solution represents a strong acidic solution or a weak acidic solution. Please

identify the strength of acidity of these solutions. Give reasons for your answer.

(6 marks)

3. Choose the correct statement below and give reasons for your choice. a. The concentration of hydrogen (H+) at pH = 1 is higher than the concentration of hydrogen

(H+) at pH = 2. b. The concentration of hydrogen (H+) at pH = 1 is lower than the concentration of hydrogen

(H+) at pH = 2.

(2 marks)

6 4. Identify from what acid and base pair we could form the following salts and write down the complete equation:

a. Sodium chloride (NaCl) salt b. Calcium sulfate (CaSO4) salt (4 marks)

5. Indicate whether each of the following statements is the characteristic of an acid or a base:

A. It has a sour taste G. It causes red litmus to turn blue or

B. It neutralizes acids BTB colour blue

+ C. It produces H ions in water H. It tastes bitter

D. It causes blue litmus to turn red or BTB I. It has a soapy/slippery feel

colour yellow. J. It neutralize bases

E. It produces OH¯ions in water. K. It liberates hydrogen gas when

F. It reacts with carbonate ion to form reacting with certain metals

carbon dioxide (11 marks)

6. Each of the following equations shows the ionization of an acid reactant or a base reactant.

Identify the acid and base reactants.

+ a. HNO3(l) + H2O(l) H3O (aq) + NO3¯(aq)

+ b. NaOH(s) + H2O(l) Na (aq) + H2O(l) + OH¯(aq)

+ c. HCl(g) + H2O(l) H3O (aq) + Cl¯(aq)

+ d. NH3 (g) + H2O(l) NH4 (aq) + OH¯(aq)

(4 marks)

7. Explain the meaning of neutralization.

7 (1 mark)

8. Write down the equation for the reaction of dilute hydrochloric acid (HCl) with:

a. Magnesium (Mg) c. Sodium hydroxide (NaOH)

b. Calcium carbonate (CaCO3) d. Calcium hydroxide Ca(OH)2) (4 marks)

9. The following substances are strong or weak acids: H2SO4, HCl, CH3COOH, H2CO3

a. Identify strong acids.

b. Identify weak acids.

c. How do you examine the strength of acids?

(3 marks)

10. Explain what you know about an acid and a base.

(1 mark)

11. The pH of normal rain is about 5.5 because of dissolved CO2. Consider a sample of rainfall with a pH of 3.5. How does the hydronium ion concentration in this sample compare with that in normal rain? Please choose the correct answer below and give an explanation for your choice.

+ a. The more acidic solution has 100 times the hydronium ion (H3O ) or hydrogen ion

(H+) concentration of the less acidic one.

+ + b. The more acidic solution has 2 times hydronium ion (H3O ) or hydrogen ion (H )

concentration of the less acidic one.

+ c. The less acidic solution has 100 times the hydronium ion (H3O ) or hydrogen ion

8 + d. The less acidic solution has 2 times the hydronium ion (H3O ) or hydrogen ion

(1 mark)

12. The following substances are strong or weak bases: NaOH, Al(OH)3, NH3, Ca(OH)2.

a. Identify weak bases.

b. Identify strong bases.

c. How do you examine the strength of the bases?

(3 marks)

Appendix D: Self-evaluation questionnaire – Students’ perceptions of their competence and confidence in carrying out the inquiry activities

Name:______Group:______Date: ______Please check (√) the box that best describes your experiences

No. Statements Always Often Sometimes Rarely 1 I handled the solutions properly

2 I made accurate observations of the changes in solutions and/or indicator 3 I followed the procedures in my inquiry plan

4 I participated productively in the group discussions 5 I listened to other members of my group and respected their ideas 6 I did my share of group work

9 7 I used my journal/workbook to record my observations and measurements 8 I used the equipment and chemicals appropriately 9 I used my sources to collect information about characteristics of acid and bases 10 I shared what I learned with others in my class

11 I shared responsibility during the presentations

12 I made good eye contact during the presentations

13 I projected my voice during the presentations