UC Irvine FOCUS!
5 E Lesson Plan
Title: Acid/Base-pH Lab
Grade Level and Course: 8th grade Physical Science, Grades 9-12 Chemistry
Materials:
Detergent-quart,
shampoo- quart
Lemon-juice-quart
Vinegar –quart
Milk-quart
Orange-juice-quart
Tomato-juice-quart
Baking-soda
Salt-shaker
Peroxide-quart
Pickle juice
Apple-juice
Containers-plastic-25
Liquid Plumber
distilled water
Rubber gloves
eye droppers
station signs
Litmus paper blue/red
acid rain
paper towels
Markers
pH chart
antacid tablets
pH paper
large containers
transparent containers
Safety glasses
Pepto Bismol
aprons
Instructional Resources Used: (concept maps, websites, think-pair-share, video
clips, random selection of students etc.)
 http://scienceview.berkeley.edu/showcase/flash/juicebar.html
 (virtual demo: Gems Alien Juice Bar)
 Use either a power-point, video or demo that will help student to become
familiar with acids, basic, and neutral solutions. Also it allows students to
understand what a pH scale is, and the pH value of indicates.
 Cooperative learning – Many of the activities in this book employ group work
and cooperative learning. Cooperative activities provide opportunities for
students to exchange, write, and present ideas. Students will work in groups
of 3s to 4s to identify the pH level of compounds.
California State Standards:
Grade 8 Physical Science:
5. Chemical reactions are processes in which atoms are rearranged into different
combinations of molecules. As a basis for understanding this concept:
e. Students know how to determine whether a solution is acidic, basic, or
neutral.
Grades 9-12 Chemistry:
5. Acids, bases, and salts are three classes of compounds that form ions in water
solutions. As a basis for understanding this concept:
d. Students know how to use the pH scale to characterize acid and base
solutions.
Lesson Objectives:
This activity is designed for students to identify the pH level of compounds. By
testing common household substances will help them:
 To understand the property of acid and base and how to test the pH of a
liquid;
 To relate the pH scale to how acidic or basic a solution is.
Differentiation Strategies to meet the needs of diverse learners:
 English Learners: KWL -Have students construct a KWL chart about acids
and bases, with the three column titles: “What I Know about Acids/Bases”;
“What I Want to Know about Acids/Bases”; and “What I Learned about
Acids/Bases”. Students will write in the appropriate columns before, during
and after doing this lab. Encourage students to use illustrations.
 Special Education: KWL strategy for the EL and also be used for special needs
students.
 GATE: Have students to research about the sources and causes of acid rain.
(Acid rain is through to be due principally to the release of sulfur oxides and
nitrogen oxides into the atmosphere). Follow by two questions:
1. How do weather patterns affect the distribution of environmental
damage due to acid rain?
2. What types of conservation efforts are used to adjust the pH of lakes
and rivers that become too acidic?
ENGAGE
 Describe how the teacher will capture the students’ interest.
Have students participate in the interactive virtual minilab that will challenge
the students to learn about acids and bases. Challenge #1 Learn about acids and
bases.
After viewing this virtual interactive activity have students discuss the following
questions.
 What kind of questions should the students ask themselves after the
engagement?
1. What was the purpose of the cabbage juice?
2. What colors were used to indicate the presence of an acid, base and
neutral solution?
EXPLORE
 Describe the hands-on laboratory activity that the students will be doing.
Students will determine whether the test substances are acids or
bases, compare pH and litmus paper as it relates to the test results.
 List the “big idea” conceptual questions that the teacher will ask to focus the
student exploration.
1. From the data collected, what generalization can you make about
the pH of a solution, and the effect of a solution on litmus paper?
2. For the following solutions, how would you describe the H30+
concentration? Label them as acidic, basic, neutral.
Solution A – pH 10
Solution B – pH 7
Solution C - pH 3
EXPLAIN What is the “big idea” concept that students should have internalized from
doing the exploration?
Acids and bases are defined by the amount of hydronium (H30+) and hydroxide ions
(H0-) that are present. Water is neutral because it has the same number of
hydronium ions and hydroxide ions. A pH scale indicates, with numbers, the
concentration of hydrogen ions in a solution and characterizes a solution as acidic
(lower than 7), basic (higher than 7), or neutral (near 7).

List the higher order questions that the teacher will ask to solicit student
explanations for their laboratory outcomes, and justify their explanations.
1. Explain why some substances are acids and some substances are bases.
2. What does it mean to say that distilled water is neutral? What pH should it
have?
EXTEND

Explain how students will develop a more sophisticated understanding of the
concept.
As an extension students may demonstrate a neutralization reaction. Students
should now be aware that acids have a pH of between 1-6. Stomach acid has a
pH of about 3. Select the most acidic solution of those tested in class that mostly
resembles stomach acid (which will be the lemon juice). Students should use the
Internet in class to research the topics “Acid Reflux” and “Heartburn”. Have
them locate over the counter medications such as Tums and Rolaids that are
used to treat these conditions, and explain how they chemically balance or
"neutralize" the pH of areas affected by heartburn. Heartburn is caused when
stomach acid regurgitates into the esophagus, causing a lowering of the pH of the
esophagus. This results in a burning sensation in the chest of a person with
heartburn.
Students may crush Tums or Rolaids into a sample of lemon juice. Students
should then retest the pH of the Lemon Juice/Rolaids or Tums Mixture. If the pH
has in fact increased, students should be able to determine if the medicine is
effective in the treatment of heartburn. Have students explain their findings in
their formal lab report.
 How is this knowledge applied in our daily lives?
The pH inside most living cells is close to 7. Because the chemical processes of
the cell are very sensitive to pH, even a slight change in pH can be harmful.
Human blood, for example, is normally maintained at a pH very close to 7.4. A
person cannot survive for more than a few minutes if the blood pH drops to 6.8
or rises to 7.8. Chemical processes ensure that the pH of blood is kept near 7.4.
EVALUATE
 How will the student demonstrate their new understanding and/or skill?
Students will know how to determine whether a solution is acidic, basic, or
neutral.
 What is the learning product for the lesson?
o Using the data from this investigation, design a pH scale by listing the
name and the pH of the substances tested.
o Students will completely and accurately fill in all laboratory data.
Background Knowledge for the Teacher:
Indicators that change color are routinely used to determine whether a solution is
acidic, basic, or neutral. A pH scale indicates with numbers the concentration of
hydrogen ions in a solution and characterizes a solution as acidic (lower than 7),
basic (higher than 7), or neutral (near 7). There are electrodes and electronic
instruments that can measure directly the pH of a solution. Some acids and bases
are defined other than by their hydrogen ion concentration, but they will be
addressed in high school chemistry. Pure water has the same number of hydronium
ions (H30+) as hydroxide ions (H0-), so it is considered neutral. 2H20 ----H30+ + 0HSources: Chemistry Lesson Plans- Middle school grades 6-8, Minnesota Science
Teaching Education Project, Science Framework for California Public Schools, for
Kindergarten through Grade 12, 2004.
Student pages are attached.
Acid/Base-pH Lab
Lesson Objectives:
This activity is designed for students to identify the pH level of compounds. By
testing common household substances will help them:
 To understand the property of acid and base; and how to test the pH of a
Liquid.
 To relate the pH scale to how acidic or basic a solution is.
Materials:
Detergent-quart,
Vinegar –quart
Tomato-juice-quart
Peroxide-quart
Containers-plastic-25
Rubber gloves
Litmus paper blue/red
Markers
pH paper
Safety glasses
shampoo- quart
Milk-quart
Baking-soda
Pickle juice
Liquid Plumber
eye droppers
acid rain
pH chart
large containers
Pepto Bismol
Lemon-juice-quart
Orange-juice-quart
Salt shaker
Apple-juice
distilled water
Electronic pH meter
paper towels
antacid tablets
transparent containers
aprons
Procedure: Acid and Base Classification
pH paper testing:
1. Obtain a 12-well plate. Note that each well is identified by a number for each
substance that will be tested. Add a few drops of each substance into the wells on
the plate.
2. For the indicator papers, dip the paper into the solution and record the color. For
the pH, use the color chart provided with the pH paper to determine the pH of
solution and record that value on your table. If the result is between two numbers,
estimate to the nearest tenth. If an electronic pH meter is available, use it to test the
pH of all test solutions.
3. Record your results in the data Table.
4. Rinse the glass rod with distilled water and proceed to test the other substances.
Record these results in the data table. After all substances have been tested with pH
paper, test each substance with red and blue litmus paper.
Litmus paper Testing:
1. The litmus paper has only two colors: red and blue. Red litmus turns blue in
the presence of bases; blue litmus turns red in the presence acids.
2. Use a glass rod to touch one drop of a test substance to a strip of red litmus
paper. If the red litmus paper turns blue, this is positive (+) for the presence
of a base. If the red litmus paper remains blue, this is negative (-). Record the
litmus results in the data table.
3. Use a glass rod to touch one drop of a test substance to a strip of blue litmus
paper. If the blue litmus paper turns red, this is positive (+) for the presence
of an acid. If the blue litmus paper remains blue, this is negative (-). Record
the litmus results in the data table.
4. Finally, in the data table, classify each of the substances as an acid, base or
neutral.
Testing unknown solutions:
1. Obtain to unknown solutions and place in well number 11 and 12. Add a few
drops of each substance into the wells on the plate.
2. Test the unknowns by using testing procedure for pH paper and Litmus
paper. Record your results in Data table.
Results
Data Table
Solution
1.
2.
3.
4.
5.
6.
pH paper
Red litmus
Blue litmus
Acid/Base/Neutral
7.
8.
9.
10.
11. Unknown
12. Unknown
Analysis Questions:
1. Explain why some substances are acids and some substances are bases.
2. What does it mean to say that distilled water is neutral? What pH should it
have?
3. List all substances tested and classify each as an acid or a base. Were any
substances neutral (or nearly so)?
4. Consider the food items tested. What conclusions, if any, can you make
concerning their pH? What conclusion can be made about the cleaning
products in general?
5. From the data collected, what generalization can you make about the pH of a
solution and the effect of a solution on litmus paper?
6. For the following solutions, how would you describe the H30+ concentration?
Label them as acidic, basic, and neutral
a. Solution A – pH 10
7. Using the data from this investigation, design a pH scale by listing the name
and the pH of the substances tested.