Sample Lesson Plan for pH Lab
Modified from Vernier Chemistry Lesson 21: Household Acids and Bases
Instructor’s Name: Caroline DeVan/Deodat Ramkissoon
Course Title: Biology
Unit: The Chemistry of Life
Topic: Acids, Bases & pH
Grade Level: 10
Rationale:
The concept of pH is abstract and the pH scale can be confusing to students. By using a lab to determine the pH
values of different household products, students will be able to better understand the concepts of acid, base, and
neutral in terms of everyday substances. The lab helps demonstrate these concepts visually using technology
and as well as providing hands-on engagement.
NJ State Standards:5.2.12.A.6: Acids and bases are important in numerous chemical processes that occur
around us, from industrial to biological processes, from the laboratory to the environment. Students will be able
to relate the pH scale to the concentrations of various acids and bases.
Instructional Goal(s):
The students will be able to determine the difference between an acid and a base and will be able to relate these
terms to a pH scale.
Performance Objective:
The students will determine pH using indicator paper and will then answer lab related questions. They will also
compare methods for obtaining pH values by use of a Vernier pH probe. They will analyze their results in a lab
report.
Lesson Content:
Students will:
 Learn about acids and bases and how they relate to pH values.
 Use universal indicator paper to determine the pH of various household substances.
 Use a Vernier pH probe to measure pH of these same substances.
 Compare the pH results of the two methodologies and determine advantages and disadvantages of each
one.
 Discuss real world examples of how pH is used.
Time frame for the Lesson:
Time Frame of Activity
5 min
15 min
35 min
15 min
10 min
Activity to be performed
Do Now: Answer pre-lab questions
Introduction of the pH scale and how acids and bases are described
in terms of pH (lecture)
Students measure pH of household substances using universal
indicator paper
Use of Vernier probe to measure the same household substances
Answer questions related to lab
Note: All times are approximate, and should be revised based upon student progress)
Instructional procedures:
a. Focusing event –Students will be asked to define the terms pH, acid, base, and neutral.
b. Bridge/ Connections – The substances used in the lab are everyday household substances. This allows
students to connect the lab with their daily lives and gives a context by which they may understand the
difference between acids and bases.
c. Teaching procedures – The students will be working in groups (4 students/group). They will
collectively answer the initial questions which will lead into the lecture about the pH scale (graphic
attached to lesson). During the lab, the teacher will provide assistance by doing demonstrations of the
procedure, answering any questions, and monitoring lab progress. After the lab activity is finished, the
Vernier pH probe will be used to measure the same substances. This will help students check their
results from the lab and will allow students to compare and contrast methods as a means of talking about
precision and accuracy of data. After both parts of the lab are done, the students will be asked to answer
questions as a group and there will be a class discussion on the importance of pH in their daily lives (lab
worksheet and procedure is attached to lesson).
d. Formative check – The teacher will be monitoring progress of the students as they perform the
experiment to ensure that they are following the protocol. In addition, the teacher will question students
while they are doing the lab to see if they understand why they are doing each part. For example,
students will be asked to complete a chart that determines whether each pH value is an acid or a base.
This allows them to give meaning to a numerical value. If students are struggling with a section, the
problematic part will be re-introduced using a different explanation. Then students will be allowed to
have more time on that section.
e. Student participation - The students will perform the lab individually using the indicator paper. The
students will then compare their results in small groups and will answer lab questions together. The
group will be graded based on a participation rubric used during labs. Volunteers will be solicited to
help with the pH probe demonstration.
f. Interdisciplinary connections – This activity integrates technology with science. The topic is about the
underlying chemical properties of life.
g. Closure- After lab activity, there will be a discussion of the lab results and questions. Students will be
asked to describe scenarios in the real world where a measurement of pH is required.
Evaluation Procedure:
The student evaluations will be done based on the participation rubric and their completion of the lab
worksheet. If a majority of the class does not demonstrate understanding of the underlying concepts of pH, then
the teacher will review the topic and allow students to have more time to complete the activity.
Materials and Aids:
The lab will require 8 household substances (both basic, acidic and neutral) in large quantities (quantity
depends on number of students in the class) and a beaker per substance for easy pouring. Some of these
substances can be a bit harsh so dilute them as needed. Safety gear of goggles, aprons, and gloves are also
required for each student. Each group will need 8- 30mL (2TBS) plastic cups (like that used to take medicine)
with a sample of each household substance. Each cup should be labeled with what it contains. Students also
need universal indicator paper strips (8 per student) and a color chart that matches the pH value to its
appropriate indicating color. Paper towels should also be on hand to clean-up spills. Containing the sample
cups on a plastic tray helps reduce spillage. For the demonstration part of the lab, you will need 1 pH sensor
and 1 Go-Link probe-USB connector, 1 laptop, updated LoggerPro software. You will also need 8- 100mL
glass beakers each with one of the household substances. The probe will be mounted on a stand using a
clamp and the sample will be held up to the probe until a steady reading has been taken. Note that the pH probe
is stored in a storage solution and so the probe requires a small vial with fresh solution contained within it. Also
note that the probe should be rinsed with distilled water between samples and gently cleaned with soap and
water and dried after use. And if necessary, the pH probe should be calibrated before the lab using standard
buffer solutions.
Household Acids and Bases
Many common household solutions contain acids and bases. Acid-base indicators, such as universal indicator
paper strips, turn different colors in acidic and basic solutions. They can, therefore, be used to show if a solution
is acidic or basic. An acid turns the universal indicator paper red, and a base turns the universal indicator paper
blue. Oranges indicate weaker acids and greens indicate weaker bases. Neutral (neither an acid nor a base)
solutions turn universal indicator yellow to yellow-green. The acidity of a solution can be expressed using the
pH scale. Acidic solutions have pH values less than 7, basic solutions have pH values greater than 7, and neutral
solutions have a pH value equal to 7.
In this experiment, you will use universal indicator paper and a color chart that indicates pH to determine the
pH values of household substances. These values will be compared to the pH values found for the same
substances using a computer-interfaced pH Sensor.
OBJECTIVES
In this experiment, you will use universal indicator paper and a pH Sensor to determine the pH values of
household substances.
PROCEDURE
1. Obtain and wear goggles and safety gloves. CAUTION: Do not eat or drink in the laboratory.
2. You will be assigned to one of four lab groups. You will work with your group to determine the pH of
common household substances.
3. There will be 8 containers labeled with a household substance that they contain. Each group will have all 8
containers at their table.
CAUTION: Handle these solutions with care. Do not allow the solutions to contact your skin or clothing. Wear
goggles and gloves at all times. Notify your teacher immediately in the event of an accident.
4. Each group will have a box of pH indicator paper strips. The strips change color when they come into
contact with a substance. The color varies depending on the pH level of the substance. Each individual
group member will dip an indicator strip (CAUTION: WEAR GLOVES!) into one of the substances and
use the chart on the indicator paper box to determine the pH of the substance. Record this number in your
data table.
5. Determine whether the substance is an acid (pH is less than 7) or a base (pH is greater than 7) or neutral (pH
of 7) and write either: acid, base or neutral in the column titled “acid or base”.
6. Continue to measure each substance individually until you have completed the first two columns of your
data table. You can ignore the column titled “pH meter” for now.
7. Help clean up the lab by throwing away any used indicator paper strips and returning unused paper strips to
your teacher. All substances will be brought to the front of the room at the conclusion of the lab.
8. We will now compare the indicator paper pH values of each substance to the pH values found while using a
computer-interfaced pH probe. Enter the pH values found with the pH probe into your data table.
DATA TABLE
Test
Tube
Solution
1
vinegar
2
Chlorox
3
orange juice
4
Sprite
5
water
6
drain cleaner
7
detergent
8
baking soda
Universal
Indicator Paper
Acid or Base
pH Probe
PROCESSING THE DATA
1. Which of the household solutions tested are acids? Explain using the data table.
2. Which of the solutions are bases? Explain using the data table.
3. List two advantages and two disadvantages of using indicator paper and the pH probe to determine pH.
4. Are the values obtained by the indicator paper always the same as those found by the pH probe? Describe
why they are the same or different.
5. Describe a real-world situation where you might need to measure pH.
pH Scale (Acid)
0-1-2-3-4-5-6-7
765 43210
Base 10
pH Scale
(Base)
7-8-9-10-11-12-13-14
0-1-2-3-4-5-6-7
Base 10