Namrta Bhardwaj
Background Information
 Prerequisite knowledge should include



nomenclature
balancing chemical equations.
Mole to mole and mass to mole calculation
 It is important that students understand the law of
conservation of mass
 Students should also be skilled in using ratios and
conversion factors in calculations.
Demonstration Video
Curriculum Expectations
Overall expectations:
 D2. Investigate quantitative relationships in chemical
reactions, and solve related problems
 D3. Demonstrate an understanding of the mole
concept and its significance to the quantitative analysis
of chemical reactions
Specific expectations
 D2.1 Use appropriate terminology related to quantities in chemical
reactions, including, but not limited to: stoichiometry, percentage
yield, limiting reagent, mole, and atomic mass [C]
 D2.5 Calculate the corresponding mass, or quantity in moles or
molecules, for any given reactant or product in a balanced chemical
equation as well as for any other reactant or product in the chemical
reaction [AI]
 D2.6 Solve problems related to quantities in chemical reactions by
performing calculations involving percentage yield and limiting
reagents [AI]
 D3.4 Explain the quantitative relationships expressed in a balanced
chemical equation, using appropriate units of measure (e.g., moles,
grams, atoms, ions, molecules)
Place in the Curriculum
Strand B
Strand C
Strand D
Strand E
Strand F-
• Matter , Chemical Trends, Chemical Bonding
• Chemical Reaction
• Quantities in Chemical Reactions
• Solutions and Solubility
• Gases and Atmospheric Chemistry
Placement Within the Unit
Counting Atoms and Molecules: The Mole
 The Avogadro Constant and the Mole
 Molar Mass
Chemical Proportions in Compounds
 Percentage Composition
 Empirical Formula of a Compound
 Molecular Formula of a Compound
Quantities in Chemical Reactions
 Stoichiometry
 Limiting Reactant
 Percentage Yield
Misconceptions / Learning
Difficulties
When the mass of both reactants is given students have difficulty
recognizing that one of the masses is limiting and the other
mass is in excess.
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

randomly select one of the given masses as limiting or excess
assume that the masses are in the correct mole ratios students
assume the smaller mass is the limiting reagent.
 Need to point out these are not trick questions
 Important to stress the common steps in converting masses into
amounts in moles in order to relate to mole ratios in balanced
equations.
Demonstrate Reaction
 Which reactant is limiting and which is in excess
reactant?
Demonstrate Mass to Mole
Relationship
 Use copper chloride reacting with Aluminum to
illustrate a mass to mole relationship
Container
Al:CuCl2
Ratio
Mass of Al Foil/g
A
B
Control
1:1 mass
ratio
1:1 mole
ratio
2:3 mass
ratio
2:3 mole
ratio
0.00
2.06
C
D
E
2.06
1.37
0.27
Misconceptions
 If reactants are in the same physical state the reaction
reaches completion when both reactants are totally
converted
Or
 If the reactants are in two different physical states
(solid and liquid) the reaction reaches completion
when the entire solid is consumed.
Reaction of Mg with HCl
Misconceptions
 Students have limited view of chemical system since
they have been taught to consider a reaction system
as: reactants -> products
 rewrite equation as:
Reactants -> Products + excess reactant
Gizmo Activity
Gizmo Activity
Gizmo Activity
Supporting Diverse Student Needs
 Challenge gifted students -How many grams of a particular




starting material will remain at the end of a reaction?
Encourage gifted students to develop their own methods
for solving problems - do not follow given format
ELL students have difficulty understanding verbal
explanations - may benefit from writing out the thought
process used in solving sample problems.
Students that required more support may be given more
scaffolding and support in questions.
Have students make common sense prediction when
solving problems.
Day 1
Lesson Sequence
Teaching Strategies
Learning Styles (MI)
Take up homework ,
Review mass to mass
calculation
Teacher directed –
student participate
Visual, Auditory
(Logical/ Mathematical)
Use hot dogs and hot dog
bun analogy to introduce
concept of limiting
reactants
Discussion
Auditory
(Verbal/ Linguistic, Logical/
Mathematical)
Demo- Na – Water rxn
Demo
Visual, Auditory (visual/
spatial)
Have students provide
alternative analogies
Think-pair-share
Auditory (Verbal/ Linguistic,
Intrapersonal, Interpersonal)
Copper chloride and
Aluminum lab
Demo
Visual, Auditory (visual/
spatial, Logical/ Mathematical)
Assessment
For learning
Homework check, assess
student’s answers as
homework is being taken
up
Day 1
Lesson Sequence
Teaching Strategies
Have students brainstorm Discussion
practical reasons for
having limiting reactants
Have students conduct
baking soda and vinegar
lab (or Mg and HCl) lab
Guided inquiry
Learning Styles (MI)
Auditory
(Verbal/ Linguistic)
Kinesthetic (kinesthetic,
visual/spatial)
Assessment
Exit pass: For the
reaction of copper
chloride and aluminum
which of the statements
is true and explain why:
Equal masses of reactants
will react completely in a
chemical equation.
Chemicals react based on
mole ratios found in a
chemical equation.
Chemicals react based on
mass ratios found in a
chemical equation.
Equal moles of reactants
will react completely in a
chemical reaction.
Day 2
Lesson Sequence
Solve sample
problems
Provide students with
a flow chart to follow
Start with balanced
chemical reactions
that has reactants in a
1:1 mole ratio
Progress to more
difficult sample
problems
Teaching
Strategies
Direct instruction
Learning Styles (MI)
Visual, Auditory
(visual/ spatial, logical/
mathematical)
Assessment
For learning
3...2...1
3 things I know about
stoichiometry.....
2 things I am getting
better at......
1 thing I still need
help with......
Days 3,4 and 5
Lesson Sequence
Day 3
Extra practice
Have groups display
answers on white
boards – gallery walk
Day 4
Quiz on limiting and
excess reactants
Percent Yield
Calculations
Day 5
Conduct Limiting and
excess lab with percent
yield calculation
Teaching Strategies
Learning Styles (MI)
Cooperative grouping Visual, Auditory
(visual /spatial, Logical/
Mathematical)
Assessment
As learning and for
learning
Assess student’s
cooperative skills,
participation skills and
answers to questions
Of learning – mark quiz
Direct Instruction
Visual, Auditory
(Logical/ Mathematical)
Guided inquiry
Visual, Kinesthetic (visual /
spatial, kinesthetic)
Of learning- collect and
mark lab
Applications and Societal
Implications
 Careers in Chemistry – Chemical Engineer
 Cooking recipes, industrial reactions, prescription
drug dosages, manufacturing, building (constructions)
 The amount of carbon on earth is the ultimate limiting
reagent for the number of people the earth can have
and in the sense that carbon is our "food"... the land
area of the earth is a "limiting reagent" that will limit
our population before carbon does....
L. H. Holmes Jr.
Advanced Preparation
 Day 1
Refer to Interactive Demonstrations for Mole Ratios and
Limiting Reagents (annotated reference 1) and prepare
material for the lab accordingly.
Refer to How Big Is the Balloon? Stoichiometry Using Baking
Soda and Vinegar (annotated reference 6) and prepare
material for the lab accordingly.
 Day 5
Refer to pg 165 of the Nelson teacher’s resource for
percentage yield in a chemical reaction lab and prepare
material for the lab accordingly.
Safety Considerations
 Remember to always wear safety goggles.
Reaction of Na with water demo
 Never use a piece of sodium larger than a ½ pea r.
 The reaction should be carried out behind a clear safety
barrier or at a distance from the students
Reaction of Copper (II) chloride with Aluminum
 Copper(II) chloride is toxic by ingestion and irritating to
skin
 Aluminum will also react with the solution to produce
hydrogen gas. Flames should not be used in this
investigation
Reaction of baking soda with vinegar
 Avoid getting baking soda or vinegar in eyes
Annotated References
Breyfogle, Bryan. (2006) Interactive Demonstrations for Mole Ratios and Limiting Reagents. Journal of Chemical Education, 85 (5), 741.
The demonstration of the mole and mass ratios for the reaction of CuCl2 and Al were obtained from this article.
Clyde, Dillard R. (1972) Two Lecture Experiments Demonstrating Limiting Quantities. Journal of Chemical Education, 49 (12), A694.
Resource used for conducting limiting reactant experiment using Mg and HCl.
Gauchon, Laure, et al. (2007) Learning About Stoichiometry: From Students’ Preconceptions to the Concept of Limiting Reactant . Chemistry
Education Research and Practice, 8 (4), 362-375.
Article discusses many misconceptions that student encounter with studying limiting reactants.
Holmes, L. H. Jr. (1998) Limiting Reagent and Kinetics: Social Implications and Malthus' Prediction. Journal of Chemical Education, 75 (8), 1004.
Interesting article that discusses food supply and land area in terms of limiting reagents.
Jenkins, Frank, et al. (2002). Chemistry 11. Toronto: Nelson. (course textbook)
Journal’s Editorial Staff (1997). How Big Is the Balloon? Stoichiometry Using Baking Soda and Vinegar. Journal of Chemical Education, 74 (2),
1328A-1328B.
Article used for the Baking soda and vinegar lab.
Resource used for conducting limiting reactant experiment using vinegar and baking soda.
Kalanter, A.H. (1985) Limiting Reagent Problems Made Simple for Students. Journal of Chemical Education, 62 (2), 106.
Article used to for the ICE method for solving limiting reactants.
Mustoe, Frank, et al. (2201). Chemistry 11. Toronto: McGraw-Hill Ryerson. (course textbook)
Annotated References
Websites:
http://www.chalkbored.com/lessons/chemistry-11.htm
good power point presentation on limiting/ excess reactants,
also the chart method for solving limiting reactant
problems was taken from this site
http://www.youtube.com/watch?v=xk7PSpFC7NI&feature=re
lated
demonstration of the flaming table and whoosh bottle
http://www.chemprofessor.com/
flow chart method was obtained from this site