Southeast Asian Ministers of Education Organization Regional Centre for Education in Science and Mathematics Penang, Malaysia
PROFESSIONAL DEVELOPMENT FOR SCIENCE AND MATHEMATICS EDUCATORS OF ACEH, INDONESIA 10 February – 8 May 2009
HOW CAN YOU DETERMINE THE ACIDITY OF A SUBSTANCE? Project Title
Ulfa Rahmi Leader Annisa Ammalia Kiti Samsul Bahari Sarong Attariq bin Huzaifah Yunizar Hendri Members
Ms. Ng Khar Thoe Project Adviser
Mr. Dominador Dizon Mangao Unit Coordinator (Science)
Mr. Lee Shok Mee Program Manager 1
Title
: How can you determine the acidity of a substance?
Year
: Secondary School, year 10 (Form 4)
Duration
: 60 minutes
INTRODUCTION
This lesson provides an array of activities to increase students’ knowledge in chemistry especially about the acidity of one material/substance. It focuses on the material that we usually use in our daily life, to identify whether the food is acid, base or neutral. Students will work in different groups to perform simple experiments, to make observations and predictions about the acidity of materials. Also, hands- on exercises are provided to enhance students’ science process skills, manipulative skills, decision making and problem solving skills. Moreover, students can develop explanations of natural phenomena in a continuing and creative process.
EDUCATIONAL OBJECTIVES
Students are expected to achieve the following:
Relate the taste of food to its chemical properties whether as acid, base or neutral.
Compare their findings with their predictions.
Classify chemicals into acid, base or neutral.
Test various food chemicals or other chemical compounds.
SCIENTIFIC CONCEPTS
Acid – Base concept
Food Chemistry
Biochemistry
Natural phenomena.
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PREREQUISITE KNOWLEDGE
Litmus paper test
Phenolphthalein indicator
TEACHING AND LEARNING MATERIAL
1. For the teacher Power point presentation, pictures, video clip, computer, LCD Projector
2. For the students Task sheets, Laboratory material (see attached activity sheet)
STUDENTS’ GUIDE
Scenario
One day, Hendri got stomach upset. He just ate a type of food then he drank orange juice, and suddenly his stomach was hurt. It seemed he got a problem with his spleen. Then his friend Attariq gave him antacid. Why did Hendri get a stomachache? Can you describe what happened to Hendri? Why did his friend give him an antacid?
Task 1.
1. Students view the PowerPoint presentation. 2. Students are to work in groups and predict the chemical properties of following material and write on your task sheet.
Water, Vinegar, Orange juice, Apple juice, Soft drink, Salt solution, Antacid, Aspirin, Coffee, Tea, Milk
3. Students are to give examples for acid, base and neutral other than the aforementioned materials.
4. Students are to: 3
a. work in groups to perform simple tests such as pH and phenolphthalein testing on samples. b. write the results of the activity on task sheet 1. c. compare the results with the prediction on task 1. d. summarize the experimental procedures that had been carried out. e. report group findings to the class.
5. Students are to answer the following question: a. What is acid? What is base? b. What is an indicator? c. How does an indicator help us figure out what is an acid, base or neutral? d. Why do we bother to test water? e. Why should we replicate experiments? 6. Students are to choose a partner and share their answer. 7. Some volunteers share their idea to the class.
Task 2. Reflection journal is given as homework.
TEACHER’S GUIDE
The students are expected to have some background knowledge on the general taste of acid and base, also a bit of knowledge about Acid and Base Theory. It is expected that the students will be able to do all the acid-base hands-on activities. Suggested Teaching Strategy
1. Teacher gives an introduction using power point presentation. 2. Students do a prediction on the chemical characteristics of some samples whether they are acid/base/neutral. 3. Students to conduct simple hands-on activities about the characteristic of acidbase. 4. Each group presents the results of their hands-on activities to the class. 5. The teacher presents power point presentation to summarize the lesson. Achieving the objectives
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Objectives
Part of the Lesson
Introduction
This is achieved by
Students to:
Develop
the
Video presentation
Power point presentation
understanding of acidity in materials that they used or consume Pre Laboratory Phase
Make predictions of the
Students do Task Sheet 1.
samples used (whether it is acid, base or neutral) Laboratory Phase
Conduct an experiment
Students continue to do
on the sample given in
Task Sheet 1 on Hands-
terms
on activity to determine
of
pH
characteristic
the
pH
and
characteristics
other of
the
samples.
Student
completes
laboratory report. Post Laboratory Phase
Relate the taste of food
Students
to chemical properties as
Sheet 2) on the experiment
acid, base or neutral
that had been carried out
Classify
chemicals
according
to
the
chemical properties
Compare the experiment results
with
prediction
ASSESSMENT
5
students’
reflection
(Task
1. Students will be tasked to complete report of hands-on activities. 2. Students will be tasked to complete reflective journals about their understanding of the lesson.
Peer Assessment Rubric in Cooperative Group Work Category
Task Time management
Observation
Team Work
3
2
1
Strongly
Partially
Don’t
Understand
Understand
Understand
Good Time Management Good observation Cooperative
Neutral
Neutral
Neutral
6
Poor Time Management Poor observation Uncooperative
Group Members 1
2
3
4
5
6
Task Sheet 1: Predicting and Observing the Properties of the Sample Substances
Introduction:
A lot of materials that we consume differ in terms of acidity. Some are acid, some are base, and probably some are neutral. Sometimes they appear in the same performance, but actually they are very different from one another. In this activity, you will investigate by observing and testing on some samples that include water or materials using some reagents.
Apparatus and substances:
10 samples of substances/material, several clean dry beakers, mortar and pestle, litmus paper, phenolphthalein indicator, dropper.
What to do:
1. Put the samples separately into small beakers using dropper. Pound those that are solid using mortar and pestle. Label your samples. 2. Observe carefully the different samples given to you. 3. Make predictions whether they are acid, base or neutral. 4. Fill up the table in the Task Sheet 1. 5. Using litmus paper test all the samples. a. Test each sample by putting the litmus paper into the beakers containing the sample. b. Write down the color changes in the litmus paper after it is soaked in the sample. 6. Record the findings of the experiments in the table 1 given in the Task sheet 1. 7. Using medicine dropper, add a few drops of phenolphthalein indicator to your samples. 8. Observe the color changes. Identify the substance as acid, base or neutral.
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Table: Predictions and Observations of the Different Samples
No
Sample
1
Water
2
Vinegar
3
Orange Juice
4
Apple Juice
5
Soft Drink
6
Salt Solution
7
Antacid
8
Panadol
9
Coffee
10
Tea
11
Milk
Prediction of Chemical Properties Acid/Base/Neutral
Observation of Experimental Process color of red litmus paper
color of blue litmus paper
Type of Substance Acid/Base/Neutral
9. Answer the following question
a. What is acid? ……………………………….……………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… What is base?............................................................................................................ ……………………………………………………………………………………… ………………………………….…………………………………………………... b. What is an indicator? ……………………………………………………….......... ……………………………………………………………………………………… ……………………………………………………………………………………… ………………………………………………………………………………………
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c. How does an indicator help us figure out what is an acid, base or neutral? ……… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… d. Why do we bother to test water? ………………………………………………….. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… e. Why should we replicate experiments? ………………………………………….. ……………………………………………………………………………………… ……………………………………………………………………………………… ………………………………………………………………………………………
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Task Sheet 2: Reflection Journal
Name: ______________________________________ Date:________________
Topic: Acid-Base
1. After this lesson, [please choose (a) or (b)]:
a. I
still
do
not
know
how
to
classify
acid-base,
because…………………………………………………………………………....... .....………………………………………………………………………………… ……….…………………………………………………………………………… ……………. b. Now I know how to classify acid-base, because…………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ………… 2. After this lesson, [please choose (a) or (b)]: a. I still do not know how to predict the material whether it is acid or base, because…………………………………………………………………………… ……………………………………………………………………………………… ……….…………………………………………………………………………… ……………. b. Now I know how to predict the material whether it is acid or base, because…………………………………………………………………………… ……………………………………………………………………………………… ……….…………………………………………………………………………… …………….
3. I think the tasks I did were [please choose (a) or (b)]: a. dangerous, because…………………………………………………………………. ………………………………………………………………………………………
b. safe, because………………………………………………………………………… ……………………………………………………………………………………… I think the tasks I did were [please choose (a) or (b)]: c. easy, because…………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……. d. difficult, because…………..…………………………………………………………… ……………………………………………………………………………………… …………………………………………………..………………………………… …….. 4. For the task in this lesson, I prefer to do it [please choose (a) or (b)]: a. alone, because………………………………………………..………………………… …………………………………….……………………………………………… ……………………………………………………………………………………… ………. b. With the group, because……………………………………………………………………. ……………………………………………………………………………………… ……………………………………………………………………………………… ……..
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