Instructional Design Template
Name of Project: Acid Clean-up
Duration: 12-15 days
Subject/Course: AP Chemistry
Designer(s): Ed Gomes
Grade Level: 11th-12th
Design Expectations
Selected Project Standards
(TEKS/CCRS)
III.A: Reaction Types
1 : Acid-base reactions; concepts of Arrhenius, Bronsted-Lowry and Lewis III.B:
Stoichiometry
1: Ionic and molecular species present in chemical systems: net ionic equations
3: Mass
and volume relationships with emphasis on the mole concept, including empirical formulas and
limiting
reactants III.C.2: Quantitative treatment of equilibrium
B.1: Constants for acids and bases; pK; pH
Big ideas Addressed in Content Reaction Types Stoichiometry Quantitative treatment of equilibrium
Standards. The student will
understand:
Student expectations addressed Acid-base reactions Net ionic equations Mass and volume relationships including limiting
reagents Constants for acids and bases: pH
in content standards. The
student is expected to:
What key knowledge will students acquire as a result of this project? What key skills will students acquire as a result of this project?
-Understand reactions between weak acids and strong/weak bases -Perform titration experiments
Understand mass and volume relationships in titrations -Understand -Analyze titration data to calculate amount of moles in solution
limiting reagents -Understand safety concerns and precautions
-Analyze titration data to calculate molar mass of unknown
-Predict products of neutralization reactions
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How will students demonstrate they have acquired this knowledge?
-Correctly predict products of neutralization rxns through net ionic
equations -Select appropriate strong and weak bases that will correctly
carry out a desired neutralization reaction -Correctly perform titration
experiments and calculations -Write a report proposing safety
procedures based on their selection of bases, including justification for
their choices
How will students demonstrate they have acquired these skills?
-Correctly predict products of neutralization rxns by writing net ionic
equations -Select appropriate strong and weak bases that will correctly
carry out a desired neutralization reaction -Correctly perform titration
experiments and calculations -Write a report proposing safety
procedures based on their selection of bases, including justification for
their choices
Guiding questions to frame the inquiry and lead students to understanding:
-What acid was spilled and what was the concentration (molarity)? -How much baking soda was truly needed to neutralize the spill
(limiting/excess reagent)? -What is an efficient and proven method to neutralize accidental acid spills?
Specific PBL Considerations
A chemical spill of an unknown weak acid occurred at a middle school in our district. A substitute teacher handled the
spill inappropriately and a student took a picture with his cell phone. The picture has leaked to the media and the district
Project Idea:
is under public scrutiny. The Board of Trustees needs AP Chemistry students to identify the spilled acid and its molarity,
Summary of the issue, calculate the amount of baking soda that was truly needed to neutralize it, and predict the product(s) of the neutralization
problem, or challenge reactions. Students need to then develop a method of neutralizing acids in such a way that teachers, substitutes, and
students just as effectively.
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Launch Details
Entry Document Details:
Show students video regarding major acid spill that Authentic Format (ex. RFP)
occurred near central China in June 7, 2011. Discuss Formal letter from district’s board of trustees
the importance of spill analyses and safety
evaluation.
STEM Connections
Acid-base chemistry
Stoichiometry/Dimensional Analysis
Use of digital technology to collect, analyze, and report data
Development of safety methods
Specific references to standards (ill defined)
Acid-base chemistry; stoichiometry
Entry Launch and
Document
Culminating Product Guidelines
-Each lab report written in AP chem. format (including data and
calculations) to be released on student created website/blog
according to teacher’s schedule (format available in resources
section)
Content Constraints
-The analysis of the acid spill is a convergent process. There is only
one unknown and molarity, and the goal is to apply titration
chemistry appropriately to find the right answer.
-The development of safety methods is a divergent process with
several possible solutions. However, two key ideas should be
present: (1) the neutralizing agent should be a weak base (2) that is
used as an excess reagent.
Time constraints
12-15 days
Material Constraints
4 weak acids
Titration lab materials
Vernier probes and TI nspire-calculator
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Facilitation Questions:
KNOW
1. Writing net ionic equations and predicting reaction products for other types of reactions
2. Understand acid structure and pH calculations
Know/Need to Know
Activity
NEED TO KNOW BASED ON LAUNCH EVENT
1. How did the Chinese government determine the acidity level in the water?
2. What do you think should be done after the clean-up is completed?
Learning Experiences
Description:
Students will create a blog or website (e.g.: wordpress or goggle sites) where they post each piece of the puzzle in the
analyses of the acid spill as they work through the project and their final recommendation for district training.
Culminating
Product/Assessment
Connections to Standards:
In doing so, the students will demonstrate their mastery of all of the following:
Acid-base reactions
Net ionic equations Mass and volume
relationships including limiting reagents
Constants for acids and bases: pH
Essential Content
Questions
Interpret shape of titration curves
Calculate the unknown molarity of an acid/base through titration calculations
Determine the molar mass of an unknown weak diprotic acid through titration
Write net ionic equations for neutralization rxns
Write safety standards based on understanding of stoichiometry and acid-base chemistry
Activity Sequence to Scaffold Content Development
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Activity/Workshop
-Acid-base reactions lab
-Post-lab includes prediction of the
products that were made based on
observation and net ionic equations
(e.g., HCl + NaOH produce a white
solid after evaporation… It must be
NaCl)
Academic Purpose/Outcome
-Allow students to experiment
neutralization rxns and other
acid/bases, etc
Content Rubric/Checklist
Elements
-Correctly write net ionic equations
for rxns b/t strong/weak
acids/bases; acids/bases + metals
Formative Assessment:
Content Elements
See left
Strategies
Have students write their own
predicted net ionic equations for
the rxns in the lab. Then teacher
can go over them as a class.
Practice problems (e.g.,
homework) with names of
reactants. Students must write net
ionic equations predicting the
products on their own.
Differentiation considerations:
Students can start working on practice problems/homework in class in groups. Teacher can then use this time to help students who are having the
greatest struggle. The goal is to allow time for each student to master this concept individually. If time allows, teacher can demo a titration before
next class so the students can be ready for next class. This activity can be spread over two days.
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Activity/Workshop
Academic Purpose/Outcome
-Titration Curves Lab (Chemistry Familiarize with shapes of
Vernier #23) and post-lab
titration curves, endpoints, and
calculations
choice of indicator
-When done, do the same for
their unknown
Content Rubric/Checklist
Elements
Formative Assessment:
Content Indicators
-Differentiate between
See left
mono/diprotic acid/base
-Choose appropriate indicator for Strategies
Go over the Vernier lab either as
their unknown
-Differentiate titration curves of a class or groups for a formative
assessment. Allow students to
strong/weak acids/bases and
then repeat the lab with their
mono/diprotic acids
unknown and use that as a
summative assessment.
Differentiation considerations:
Students who complete the lab and conclusions successfully can start the analyses for their unknown immediately. Teacher can then work with
students who need practical help on using equipment and/or technology. Heterogeneous grouping will allow students to help each other as they
work through this project. Up to 2 days for this activity.
Activity/Workshop
Academic Purpose/Outcome
-Acid-Base Comp. Lab (Adv. Chem Combination of acid-base rxns and
Vernier #7) and post-lab
stoichiometry
calculations
-After completed, students do the
same procedures for their unknown
Content Rubric/Checklist
Elements
Correctly calculate the unknown
molarities
Formative Assessment:
Content Elements
See left
Strategies
Vernier lab write-up includes postlab questions/calculations. Students
work as a group and teacher can go
over calculations as a class/or
groups. Students do calculations for
their unknown as summative.
Differentiation considerations:
Some students will struggle with stoichiometry calculations, especially for the diprotic unknowns. Heterogeneous grouping might allow students
to help each other as they work through this project. Up to 2 days for this activity.
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Activity/Workshop
-Titration of Diprotic Acid (Vernier
#25) (determination of molar mass)
and post-lab calculations
Academic Purpose/Outcome
Content Rubric/Checklist
-Higher level evaluation and
Elements
synthesis of stoichiometry and acid- -Correctly calculate the molar mass
base rxns concepts
of diprotic unknown
-Error analysis
-Error analysis
Formative Assessment:
Content Elements
See left
Strategies
Again, use the Vernier lab as a
formative assessment where
students work in groups first and
teacher goes over information when
all are done or individually in
groups. Error analysis in post-lab
calculations is important. Later,
students complete lab as part of
project/summative assessment.
Differentiation considerations:
Vernier lab can be reviewed individually, groups, or whole class. Up to 2 days for this activity. Teacher may choose to do a known diprotic acid
with the students and then later allow them to complete the lab with the unknown. The teacher might also allow the students to work directly on
the unknown as summative work. They’ll have done a lot of titrations by now and will have a lot of experience with the equipment and
calculations. Depending on the level of different students/groups, the teacher can allow some to go straight to working with their unknown while
others do a practice run with the teacher first.
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Activity/Workshop
Academic Purpose/Outcome
Calculate amount of baking soda in Stoichiometry analysis in grams
grams that was necessary to
(not just molarity).
neutralize spill.
Content Rubric/Checklist
Elements
Correctly compute amount of
baking soda necessary in grams.
Formative Assessment:
Content Elements
See left.
Strategies
At this point, students have had
extensive practice in stoichiometry.
Teacher should give some feedback
in setting up problems with set up
but not calculations. Calculations
are summative.
Differentiation considerations:
Ideally, at this point, AP Chemistry students have mastered stoichiometric calculations. Some will do this very quickly. Students who struggle
should work in a group and depend on teacher minimally. Teacher should give feedback on set up but allow students to work mostly
independently. Ideally, 30 minutes max should be devoted to this.
Activity/Workshop
Develop clean up method.
Academic Purpose/Outcome
Content Rubric/Checklist
Formative Assessment:
Demonstrate understanding of acid- Elements
Content Elements
base neutralization rxns (weak v. -Selected bases should, in most
See left
strong) and stoichiometry (what
cases, be weak and in the solid state
should be the limiting reagent).
-Student should conclude that the Strategies
base must be the excess reagent
-Check with students periodically
-There are many possible choices of (informal assessment). Ask them
bases that would be appropriate
whether the neutralizing base should
be (1) a strong/weak base and (2)
limiting/excess reagent.
-Schedule some time for peer
assessment with student from a
different group then the group
they’ve been working with
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Differentiation considerations:
If students are struggling with coming up with the procedures, give them guiding questions: (1) should you select strong or weak bases? Why? (2)
What must be the excess reagent, the acid or the base? (3) Pick some bases that meet your criteria for #1. (4) Write your safety method. 1-1.5 days.
Continue here if additional activities/experiences will be used:
If desired, the teacher can continue the project throughout an acid-base equilibrium unit. Students can calculate pKa’s for the two protons in their
diprotic unknown and complete error analysis.
Other Planning Considerations
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Resources
Launch event video
Entry document
Acid-base rxns lab: some ideas below
 Strong acid + strong base

Strong acid + weak base

Weak acid + strong base

Weak acid + weak base

Metal + acid

Other rxns. Expose students to as many as possible.
Products should be analyzed qualitatively and quantitatively to help students predict the products. Some examples follow below. Teacher can
choose reactions based on what s/he has available in a chemical storage.
 Zn + HCl  H2 + ZnCl2 Hydrogen gas that is released can be trapped and “lit” with a wooden splint. Students should connect flammable
gas with hydrogen (if they know that information).

HCl + NaOH  H2O + NaCl Place in evaporating dish and allow to boil. White solid will be left. See if students can predict the product
is table salt based on the formulas of reactants. Or if rxn is done carefully, if the solution’s pH after rxn is done should be near pH 7. That
will lead students to predict that one of the products is H2O.
Vernier Labs
Vernier Probes TI-nspire calculator can be used for data collection from the Vernier probes.
Lab rubric
Student checklist: Can be used as a rubric if teacher adds points.
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Other
None of the learning experiences above include the Launch Event, Entry Document, or Know/Need to Know activity. These are very important to
engage students and to help them internalize the material learned.
Required prior knowledge:
 Basic understanding of acid-base theory (Arrhenius, Bronsted-Lowry, Lewis)

Distinguish strength of acids based on dissociation in water

Writing net ionic equations (for other types of reactions, such as precipitation rxns)

Stoichiometry and limiting reagents (this project allows students to apply topics learned in stoichiometry unit while learning about acidbase rxns and titrations)
I suggest giving the following information to students with the entry letter, or soon thereafter. The letter does not give sufficient information for
the project to be completed. It might be of benefit to see if any of the topics mentioned below show up in the Know/Need to Know activity. Also
the material below provides necessary constraints for the students.
A package of four weak diprotic acids arrived at a science teacher when a substitute was present. The box fell and one of the bottles spilled.
Unfortunately, the chemical labels had been inappropriately labeled and were smudged. In desperation, the substitute asked one of the 7th graders
what to do and was advised by one student to pour baking soda on the spilled acid. The substitute teacher poured 500g of baking soda onto the
acid. The clean-up ended up being very messy. Out of desire to help the substitute teacher, several students ended up touching the mixture. A
student took a picture with his cell phone and forwarded it to his parents. As you know, the picture has made its way to the school board and the
media. All solutions were in 1L bottles. The bottle that spilled did not lose all the acid. 351mL was retained and we have shipped it to you with
this letter (this letter is the entry document).
Here is the list of acids that the science teacher had ordered. Most of these acids are weak acids that are commonly found in food.
1. Oxalic acid
2. Tartaric acid
3. Malic acid
4. Ascorbic acid
The spill analysis section of this project is purely convergent and matches the style of the AP exam. The safety development is divergent and
allows the student to apply qualitative principles of stoichiometry and acid-base neutralization reactions to a problem with several possible
efficient solutions.
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