Video Presentation Title: The Chemistry of Water Quality Tests
Unit of Instruction: Chemical Reactions
Standard(s):
AP Chemistry: Enduring understanding 3.A: Chemical changes are represented by a balanced chemical equation that identifies the ratios with which reactants react and products form. Essential knowledge 3.A.1: A chemical change may be represented by a molecular, ionic, or net ionic equation. Enduring understanding
3.B: Chemical reactions can be classified by considering what the reactants are, what the products are, or how they change from one into the other. Classes of chemical reactions include synthesis, decomposition, acid-base, and oxidation-reduction reactions.
Essential knowledge 3.C.1: Production of heat or light, formation of a gas, and formation of a precipitate and/or a color change are possible evidences that a chemical change has occurred. Essential knowledge 2.A.3: Solutions are homogenous mixtures in which the physical properties are dependent on the concentration of the solute and the strengths of all interactions among the particles of the solutes and solvent. Essential knowledge 1.D.3: The interaction of electromagnetic waves or light with matter is a powerful means to probe the structure of atoms and molecules, and to measure their concentration. LO 1.16 The student can design and/or interpret the results of an experiment regarding the absorption of light to determine the concentration of an absorbing species in a solution.
Subject/Course: Advanced Placement Chemistry
Objective(s): Connect video to student experiences with water quality and the principles of recycle, reduce, and reuse.
Facilitate discussion and student questioning.
Reinforce the use of data and observations regarding the common reactions categories. Understanding the role of evidence collection combined with use of a scientist’s senses and available instrumentation to conduct water quality testing.
Page 1 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant, Northampton, PA

Assessment/Demonstration of Learning: Supporting evidence for maintaining water quality is provided by students after seeing the water cycle and the concerns of discharges all along the Mississippi
River. Also, their individual and group responses to the solution of the given problem, and their writing of a molecular equation, and rewriting the molecular as a net ionic equation. Their research, proper scientific vocabulary, descriptions, concepts of reaction equilibrium and concentrations leading to precipitation.
Resources Needed: A summary of the 5 types of reactions with examples, a list of solubility rules, a college-level chemistry book to provide Ksp values, an appropriate search engine (Google, Bing, etc.), the EPA website (listed below) and the Spark 101 case study video.
Student and teacher worksheets (following the lesson plan and posted online).
Lesson Component
Activator
(Prior to showing the video presentation)
Time Allotted
Time:
5 minutes
Grouping:
Pairs
Problem/Motivation
(Part I of video)
Time:
5 minutes
Teacher Procedure
(First day of class)
Facilitate “KWL”
Ask students what knowledge they have about the availability and quality of fresh water in certain parts of the USA and/or other locations.
Ask students to list what they already KNOW about methods of separating mixtures based on physical properties. List what they think are the key principles for common techniques for separation of mixtures.
Students are paired to discuss what they have LEARNED.
Problem: Propose a foundation of a good water quality test for the presence of barium.
Show the first segment of the video to your students. Let them know that after viewing the video, they will be selecting an appropriate chemical reaction to isolate and determine the concentration of a selected water contaminant
(barium).
Page 2 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant, Northampton, PA

Problem Solving
Activity
(Describe process for identifying possible solution(s) to the problem presented)
Solving the Problem
(Part II of video)
Time:
30 minutes
Grouping:
Small groups (3-5)
Time:
15 minutes
Have students use a search engine to begin to research and record the physical and chemical properties of barium. Begin to use the template “Give One, Get
One, Move On”.
Solutions: Given what you know, identify the procedures that you would use and to isolate and determine barium’s concentration. Keep in mind the criteria for a good water quality test.
Checks for Understanding
Solutions: What are the safety and health considerations of barium wastes in a water supply? Given what you know, what are at least 2 ways to identify, isolate, and test water samples for barium? What are the constraints of barium detection?
(Second day of class) Give students time to complete the template “Give One,
Get One, Move On”. Next, show this second segment of the video to your students, letting them know that they will be comparing their solutions to the actual solution shared by the industry professionals.
Pause here to check-in for student understanding.
Comparing Solutions and Meaning
(Describe process for identifying possible solution(s) to the problem presented)
Future Impact and
Meaning
(Part III of video)
Future Impact and
Meaning
(Have students reflect on how solving the problem might relate to current or future goals)
Time:
2 minutes
Grouping:
Whole group
Time:
2-5 minutes
Time:
2 minutes
Grouping:
Independent
Checks for Understanding
How did your selected reaction compare to the expert’s formulation?
Show this third and final segment of the video to your students, letting them know that they will be reflecting on their thoughts related to pursing possible education pathways and careers presented in the video.
Checks for Understanding
Individual Reflection: In what ways does water quality impact you and future generations?
Page 3 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant, Northampton, PA

Summarizer/Closure Time:
20 minutes
After viewing the video, students will be asked to extend the ideas presented in the video and their research, presenting the data gathered from the websites to provide evidence for the following: a. The design and/or interpretation of the results of a separation experiment (filtration, paper chromatography, column chromatography, or distillation) are in terms of the relative strength of interactions among and between the components. b. The translation of an observed chemical change into a balanced chemical equation and justification of the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. c. Production of heat or light, formation of a gas, and formation of a precipitate and/or a color change are possible evidences that a chemical change has occurred. d. That stoichiometric calculations are used to predict the results of performing a reaction in the laboratory and/or to analyze deviations from the expected results. e. That the student can design and/or interpret the results of an experiment regarding the absorption of light to determine the concentration of an absorbing species in a solution. f. That quantities (measured mass of substances, volumes of solutions, or volumes and pressures of gases) are used to identify stoichiometric relationships for a reaction, including situations involving limiting reactants and equilibrium situations in which the reaction has not gone to completion. g. The solubility of a substance can be understood in terms of chemical equilibrium. h. The prediction of the solubility of a salt, or ranking of the solubility of salts, can be done given the relevant Ksp values. i. The interpretation of data regarding solubility of salts to determine, or rank, the relevant Ksp values.
Assessment (if applicable)
Additional Notes (if needed)
Student prior knowledge was a. In a solution (homogeneous mixture), the macroscopic properties do not vary throughout the sample. This is in contrast to a heterogeneous mixture in which the macroscopic properties depend upon the location in the mixture. The distinction between heterogeneous and homogeneous depends on the length scale of interest. As an example, colloids may be heterogeneous on the scale of micrometers, but homogeneous on the scale of centimeters. b. Solutions come in the form of solids, liquids, and gases. c. For liquid solutions, the solute may be a gas, a liquid, or a solid.
Page 4 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant, Northampton, PA

CK12 Connections (if available) d. Based on the reflections of their structure on the microscopic scale, liquid solutions exhibit several general properties:
1. The components cannot be separated by using filter paper.
2. There are no components large enough to scatter visible light.
3. The components can be separated using processes that are a result of the intermolecular interactions between and among the components. e. Chromatography (paper and column) separates chemical species by taking advantage of the differential strength of intermolecular interactions between and among the components. f. Distillation is used to separate chemical species by taking advantage of the differential strength of intermolecular interactions between and among the components and the effects these interactions have on the vapor pressures of the components in the mixture.
For the EPA Contaminant list, go to: http://water.epa.gov/drink/contaminants/index.cfm
OpenStax Connections (if available)
Page 5 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant, Northampton, PA

1. Synthesis reactions: combine multiple elements or compounds into one species.
– Ex: Hydrogen and oxygen react:
– 2 H
2
(g) + O
2
(g)  released.
2
O (l) ; Driving force: products are more energetically stable than the reactants, energy is
2. Decomposition reactions: break one species into multiple elements or compounds.
– Ex: Decomposing sodium hydrogen carbonate
– 2 NaHCO
3
(s)+ heat 
2
CO
3
(s) + H
2
O (l) + CO
2
(g) ; Driving force: products are more stable than reactants, increase in entropy as a gas is produced.
3. Redox reactions: electron transfer reactions; a substance is reduced and another is oxidized.
– a. Combustion of methane
– CH
4
(g) + O
2
(g)

CO
2
(g) + 2 H
2
O (l) ; Driving force: products are more stable than reactants, energy is released, oxygen is reduced and methane is oxidized.
– b. Calcium reacts with hydrochloric acid
– Molecular (Full) form: Ca
(s) + 2 HCl aq)

CaCl
2
(aq) + H
2
(g)
– Net Ionic form: Ca (s) + 2H + (aq)  Ca 2+ (aq) + H
2
(g) ; Driving force: products are more stable than reactants, energy is released, hydrogen is reduced and calcium is oxidized.
4. Precipitation reactions: a double displacement reaction where spectator ions are present, Q>Ksp, and a solid forms from mixing solutions.
– silver nitrate and sodium chloride solutions are combined
– Molecular (Full) form: Ag
NO
3
( aq) + NaCl (aq)

Na NO
3
( aq) + AgCl(s)
– Net Ionic form: Ag + (aq) + Cl (aq)  AgCl(s) ; Driving force: an equilibrium condition with an insoluble solid and its ions, favoring solid formation.
5. Acid-Base reactions: proton transfer reactions
– ammonia and water are combined
– NH
3
(g) + H
2
O(l)  NH
4
+ (aq) + OH (aq) ; Driving force: an equilibrium condition whereby competition for protons favors the more stable species.
Page 6 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant,
Northampton, PA

Rule 1: Compounds of NH
4
+ and group 1A metal ions are soluble.
Rule 2: Compounds of NO
3
–
, ClO
4
–
, ClO
3
–
and C
2
H
3
O
2
–
are soluble.
Rule 3: Compounds of Cl
–
, Br
–
and I
–
are soluble except those of Ag + , Cu + , Tl + , Hg
2
2+ and Pb 2+ .
Rule 4: Compounds of SO
4
2 –
are soluble except those of Ca 2+ , Sr 2+ , Ba 2+ and Pb 2+ .
Rule 5: Most other ionic compounds are insoluble.
Page 7 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant,
Northampton, PA

1. Research the type and sources of chemical wastes found in water by using the EPA Contaminant list, at http://water.epa.gov/drink/contaminants/index.cfm
2. Use a search engine to research water contaminants that have colors. Indicate appropriate wavelengths for colorimetric determination of the concentrations of the ions.
3. Use an AP Chemistry textbook to look up Ksps of three insoluble compounds that contain possible anion or cation water contaminants. a.
Write Ksp expressions for the equilibrium between the insoluble compounds and their ions. b.
Calculate the molar solubilities of these compounds. c.
Rank the solubilities of these insoluble compounds based on their calculated gram solubilities. d.
Provide a procedure for separation of a mixture of these insoluble compounds in a water sample. e.
Indicate which compound precipitates first in the mixture for letter (d).
Name ___________________________________________ Date: ____________________________________
Class Period ___________________
Page 8 of 8
© 2014 Spark 101 Developed by John Hnatow, AP Chemistry consultant,
Northampton, PA