Course Profile Chemistry (SCH4C), Grade 12, College Preparation, Public
Unit 2: Chemical Calculations
Time: 20 hours
Activity
2.1 | Activity 2.2 | Activity 2.3 | Activity 2.4
| Activity 2.5
Unit Description
This unit is
designed to expand the basic skills and knowledge of qualitative analysis,
encountered in Unit 1, to quantitative analysis, since this combination is
required for ensuing units. Real-life examples are used wherever possible and
skills are introduced in the context of technical careers to allow students to
appreciate chemistry in a practical setting. The activities show a progression
towards independent note taking and lab skills, with an emphasis on proper lab
technique, accuracy of results and procedures, and standardized recording of
data and results, as would be required in the pharmaceutical industry, and by
the International Organization for Standardization (ISO) or Canadian Good
Manufacturing Practices (CGMPs). The unit begins with a discussion on the
importance of accurate quantitative chemistry in industrial settings, including
Canadian industries, and an introduction to the mole concept. Mole quantities
are applied to both theoretical (calculating and quantifying relationships in
chemical equations) and experimental (preparing and reacting standard
solutions) situations. The End-of-Unit-Task involves designing an experiment to
determine the quantitative identity of a substance, in preparation for Unit 6
Final Assessment Tasks. It must be noted that this unit is
mathematics-intensive as well as lab-intensive, with a focus on the skills
required for quantitative analysis in industry, e.g., quality control lab.
Students are therefore advised to review basic algebraic manipulations,
calculations, and ratios. Teachers should adapt the complexity of chemical
calculations to the degree required to address the expectations. If such
equipment is available, this is also a good unit in which to introduce micro-chemistry,
since this simulates many “real-life” labs and reduces waste and chemical
pollution in the environment. Proper disposal of materials in an
environmentally responsible manner must be emphasised.
|
Activity/ Time |
Learning Expectations |
Assessment Categories |
Task/Focus |
|
2.1 4 h |
CCV.01, CCV.02,
CCV.03, CC1.01, CC2.02, CC2.03, CC2.05, CC3.01, CC3.02 |
Knowledge/
Understanding |
·
notes ·
discussion ·
problems ·
results sheet ·
student-generated
results sheet (effectiveness as a tool) |
|
2.2 5 h |
CCV.02, CCV.03,
CC2.01, CC2.02, CC2.05, CC2.06, CC2.08, CC3.01, CC3.02 |
Knowledge/
Understanding |
·
lab ·
procedure for
calibration curve ·
calibration
curve ·
problems |
|
Activity/ Time |
Learning Expectations |
Assessment Categories |
Task/Focus |
|
2.3 5 h |
CCV.01, CCV.02, CCV.03, CC1.02, CC1.03, CC2.01, CC2.02, CC2.05,
CC2.06, CC2.07, CC2.08, CC3.02, CC3.03 SIS.01, SIS.02, SIS.03, SIS.04, SIS.05, SIS.07, SIS.08, SIS.09 |
Knowledge/ Understanding |
· problems · lab |
|
2.4 2 h |
CCV.02, CC2.04 |
Knowledge/
Understanding |
·
theoretical
problems |
|
2.5 |
CCV.01, CCV.02,
CC1.01, CC1.02, CC1.03 CC2.01, CC2.02, CC2.03, CC2.04, CC2.05, CC2.08 |
Knowledge/ Understanding
|
·
effective
procedure ·
lab technique ·
results ·
end-of-unit
test |
Time: 4 hours
In this activity,
students begin with a review of basic mathematics and chemistry concepts before
extending their knowledge of chemicals and chemical reactions from qualitative
to quantitative analysis. Students realize the importance of accurate
measurements in industrial applications and labs and are introduced to the
concept of the mole as one of the most important measurements in chemistry, as
opposed to other measures they may be more familiar with, e.g., mass and
volume. Students participate in a series of activities that clarify the mole as
a quantity similar to a dozen, in that it represents a physical number of
particles, which is independent of material. The focus of this set of
activities is the relationship among moles, mass, and number of particles in
various chemicals. In preparation for technical training in a college setting,
this activity introduces the use of Standard Results Sheets to record
experimental data instead of formal lab reports. Technology may be integrated
into this activity, with students constructing a class website, with teacher
assistance, and uploading both theory and calculations to it.
Strand(s): Chemical Calculations
Learning
Expectations
CCV.01 - demonstrate
an understanding of the mole concept as well as of quantitative relationships in
chemical reactions;
CCV.02 - use
techniques of quantitative analysis in the preparation of standard solutions
and solve problems involving the analysis of quantities in chemical reactions,
using both theoretical and experimentally measured quantities;
CCV.03 - explain the
importance of quantitative chemical relationships in industry and in everyday
life;
CC1.01 - define the
mole concept and demonstrate an understanding of its usefulness in the analysis
of quantities involved in chemical reaction;
CC2.02 - conduct
quantitative analyses, using correctly and accurately the following
instruments: pipette, burette, volumetric flask, spectrophotometer, electronic
balance;
CC2.03 - calculate
the molecular mass and molar mass of a compound with the aid of the periodic
table;
CC2.05 - solve
problems involving relationships among the following variables: quantities in
moles, mass, number of particles, concentration, volume of solution;
CC3.01 - give
examples of everyday situations in which an understanding of quantitative
relationships of substances is important;
CC3.02 - explain why
it is important to ensure accuracy in the concentration of certain solutions;
SIS.01 - demonstrate
an understanding of safe laboratory practices by selecting and applying
appropriate techniques for handling, storing and disposing of laboratory
materials and using appropriate personal protection;
SIS.02 - select
appropriate instruments and use them effectively and accurately in collecting
observations and data;
SIS.03 - demonstrate
the skills required to plan and carry out investigations using laboratory
equipment safely, effectively, and accurately;
SIS.04 - demonstrate
a knowledge of emergency laboratory procedures;
SIS.05 - select and
use appropriate numeric, symbolic, graphical, and linguistic modes of
representation to communicate scientific ideas, plans and experimental results;
SIS.06 - select,
integrate and interpret information derived from experiments and from print and
electronic sources, including Internet sites, and, either in writing or using a
computer, compile and display the information in various forms, including
diagrams, tables, graphs and laboratory reports;
SIS.07 - express the
result of any calculation involving experimental data to the appropriate number
of decimal places or significant figures;
SIS.08 - select and
use appropriate SI units;
SIS.09 - identify
and describe science and technology-based careers related to the subject area
under study.
·
Basic arithmetic
and algebra, such as manipulating equations and using division and
multiplication appropriately for different calculations
·
Knowledge of
different classes of chemicals and material from Grade 9 and 10 Science, e.g.,
chemical formulae for some common compounds, chemical reactions, nomenclature
of both ionic and covalent compounds, reactants, products and the phases in
which reactants and products are available (solid, liquid, gas and aqueous)
·
Prepare a
diagnostic activity on the following topics: identifying the number of atoms of
each element from chemical formulae of ionic and covalent compounds, reactants,
products in a reaction, phases in which reactants and products are available
(solid, liquid, gas and aqueous).
·
Prepare a series
of real-life examples of situations where chemical accuracy is important and/or
essential to life.
·
Gather/prepare
sample graphic organizers.
·
If possible,
facilitate access to webpage building software and presentation software.
·
Gather print and
electronic material for students emphasizing chemical technique and safety in
different industries.
·
Prepare review
problems for students to practise basic arithmetic, manipulating formulae and
conversion skills if necessary for review.
·
Prepare problems
on mole quantities, along with detailed answers, emphasizing real-life
applications. Include both Canadian and global industries and other settings in
these problems.
·
Prepare
instruction sheets for how to calculate molar mass from formulae, to be used in
Activity 2.1.3, as well as a Standard Results Sheets, specific for Activity
2.1.3.
·
Gather ionic
compound and molecular compound models for students to use as manipulatives in
determining molar mass, e.g., marshmallows and toothpicks, molecular models.
·
Gather safety
equipment for the lab: goggles, aprons, and gloves.
·
Gather materials
for lab activity: common over-the-counter pharmaceuticals, balances, weighing
boats, spatulas, beakers, solid chemicals, e.g., sodium chloride, sodium
sulphate, calcium carbonate, potassium nitrate, copper(II) carbonate, iron(III)
oxide. If possible, use micro-chemistry equipment.
·
Have available a
list of active ingredients for the different household pharmaceuticals, where
they are manufactured and their chemical formulae for students to refer to, if
necessary.
·
Follow board
policy for proper safety in the handling and disposal of all chemicals,
including the pharmaceuticals.
2.1.1 Student
Activity: Students participate in a discussion of everyday examples of
situations where an understanding of quantitative relationships among
substances is important, e.g., the pharmaceutical industry. They realize the
importance of maintaining and ensuring accuracy in these situations, e.g.,
right strength of intravenous (IV) drip in hospitals, and link profitability
and percentage yield. Students may work in small groups and generate a
collective class list of important points of the discussion, using additional
resources to integrate and report their information in a graphic organizer
(concept map, informative webpage). They may present their findings using
presentation software and/or engage in a debate. Students are introduced to the
End-of-Unit Task and reminded of the Final Assessment Task.
Teacher Facilitation: The teacher facilitates a discussion on the
importance of chemistry in different industries. Lead the discussion or guide
students in their discussions. Allow students to work in small groups and allow
the use of additional resources, e.g., access to presentation software, access
to webpage building instructions, examples of sample graphic organizers to
support a debate. Summarize the major points of the discussion, and major
examples of real-life situations where accuracy in chemistry is important, to
conclude the discussion. Introduce the End-of-Unit task and remind students of
the Final Assessment Task.
2.1.2 Student Activity: Students
complete a diagnostic activity on basics of chemical reactions.
Teacher
Facilitation: The teacher sets
up a diagnostic activity, e.g., “lab-stations,” online quiz to assess student
qualitative knowledge of chemical reactions before proceeding into quantitative
chemistry. Lab stations may include: identifying the number of atoms of each
element from chemical formulae of ionic and covalent compounds, reactants,
products in a reaction, phases in which reactants and products are available
(solid, liquid, gas and aqueous). Depending on the results of the diagnostic
activity, it might be necessary to prepare review activities. These could be
individualized. As part of the follow-up, the teacher introduces the
End-of-Unit Task with reference to the Final Assessment Task, allowing time for
students to ask clarification questions regarding the task and/or its
assessment.
2.1.3 Student
Activity: Students determine the formula and/or molecular mass of an
assigned group of molecules/ionic compounds from the average atomic mass of the
constituent atoms, as read from a periodic table. They complete a Standard
Results Sheet (see Appendix B) and generate notes on calculating molecular mass
from a teacher-led lesson and the activity. They may compare their notes to
those made available by the teacher. Student notes could take on a variety of
formats depending on student learning style.
Teacher Facilitation: The teacher provides students with models of
individual and/or groups of molecules and ionic compounds. Generate a Standard
Results Sheet for students to use. Compile notes on calculating molecular mass
and post these for students to compare to their own. These notes should be
presented in a number of formats to encourage students to employ a method
suited to their learning style. Notes may be posted online.
2.1.4 Student
Activity: Students note that that mole is a quantity similar to a dozen
(12) or a ream (500 pages). They also note the relationship among moles, mass,
molar mass and Avogadro’s number and that the terms molecular mass/formula mass
and molar mass are synonymous, for calculation purposes. They follow a
demonstrated method of analysis to solve problems and present their work in
organized fashion. Students may work in groups or individually.
Teacher Facilitation: The
teacher provides students with problems on converting quantities of different
materials into quantities of moles, e.g., number of shoes to moles of shoes;
moles of atoms into numbers of atoms, and mass of molecules into moles. The
teacher may lead into these problems with problems on converting dozens and
gross, in order to address student misconceptions about the mole. Review the
relationship among moles, mass, molar mass and Avogadro’s number. Also review
synonymous new terminology, e.g., formula mass/molecular mass and molar mass.
The teacher may provide formula triangles to help students with mathematical
conversions and demonstrate a structured method for solving these problems such
as G.R.A.S.P (Given, Required, Analysis, Solution, Paraphrase) or G.R.A.S.S.S
(Given, Required, Analysis, Solution, Statement, Synthesis). The teacher may
allow group work and provides assistance as necessary.
2.1.5 Student
Activity: Students determine the quantity, in moles, of an assigned
chemical sample, demonstrating proper lab safety procedures and proper
technique for using balances.
They complete a Standard Results Sheet. They then use different
pharmaceuticals, e.g., antacid tablets to determine the quantity in moles of
the active ingredient present in one dosage, from the given or researched
formula. For this, they generate their own results sheet. Students may also
generate a table, from class data, comparing the amount of active ingredient in
various similar pharmaceuticals, e.g., ranitidine in Zantac® and in
generic ranitidine.
Teacher Facilitation: The teacher explains to students that
pharmaceuticals are chemicals and must be handled as such, and also reminds
students of the safe handling and disposal procedures for all the chemicals
being used. Provide students with assigned chemicals and balances to be used,
as well as a Standard Results Sheet. The teacher may provide students with the
formula of the active ingredient or guide students in researching the formula,
e.g., Aspirin®, active ingredient is acetylsalicylic acid, chemical
formula C9H8O4; Zantac® for
acidity, active agent is ranitidine hydrochloride, chemical formula C13H22N4O3S.HCl;
Aludrox® for hyperacidity, active agent is alumina, chemical formula
is Al(OH)3; Baygon® for insecticide spray, active agent
is propoxur, chemical formula C11H15NO3; Oxy®
for acne, active agent is benzoyl peroxide, chemical formula is C14H10O4;
Zovirax® for cold sores and herpes, active agent is acyclovir,
chemical formula is C13H20N6O4.
· The teacher monitors and assesses students on their effective participation in group work (discussions, reviewing problems and lab work) as well as individual performance in the classroom (note taking, participating during teacher-led lessons, reviewing problems). Assigned problems should be assessed to gauge student understanding of the basics of quantitative analysis in chemistry. By assessing the results sheet for safety, technique, and accuracy in both recording and calculations, the teacher can set the tone for a safe and accuracy-oriented lab environment. Also, the independent investigation can be assessed on effectiveness of student-generated results sheet as a data recording tool and the accuracy of results.
· Problem Sets (K/U, MC), Formula/Molecular Mass Results Sheet (I, C), Moles of Active Ingredient (I, C)
·
Some students may
be sensitive to some or all of the chemicals that are used in this activity.
Adaptations include not using these particular chemicals, or allowing students
to work from previously collected data.
ISO website
– www.iso.ch/
WHO website
– www.who.int/
Health
Canada Therapeutics Protection Programme website – www.hc-sc.gc.ca/hpb-dgps/therapeut/
Chemistry: a
Brief History – www.nidlink.com/~jfromm/history2/chemist.htm
Chemical
calculations (worksheets and problems):
– www.tntech.edu/www/acad/chem/jackson/notes7.htm
–
www.mhhe.com/catalogs/sem/chemistry/
–
www.wpbschoolhouse.btInternet.co.uk/page04/4_73calcs.htm
–
www.tntech.edu/www/acad/chem/jackson/notes7.htm
–
www.mhhe.com/catalogs/sem/chemistry/
–
www.wpbschoolhouse.btInternet.co.uk/page04/4_73calcs.htm
Time: 5 hours
This activity commences with an introduction to
the concepts of concentration and dilution. One or both of these concepts may
be introduced in connection with mole quantities. Proper technique for
preparing solutions is demonstrated and students use these techniques to
prepare solutions of required concentration from solids and from other
solutions. When diluting solutions from a standard to a required concentration,
students calculate concentration from simple volume ratios. Students should be
introduced to the dilution formula: C1V1 = C2V2.
The activity concludes with students using their skills in preparing solutions
to generate an experimental calibration curve and perhaps use this to predict
concentration. They may use Probeware in this activity.
Strand(s): Chemical Calculations
Learning
Expectations
CCV.02 - use
techniques of quantitative analysis in the preparation of standard solutions
and solve problems involving the analysis of quantities in chemical reactions,
using both theoretical and experimentally measured quantities;
CCV.03 - explain the
importance of quantitative chemical relationships in industry and in everyday
life;
CC2.01 - use
appropriate scientific vocabulary to communicate ideas related to
stoichiometry;
CC2.02 - conduct
quantitative analyses, using correctly and accurately the following
instruments: pipette, burette, volumetric flask, spectrophotometer, electronic
balance;
CC2.05 - solve
problems involving relationships among the following variables: quantities in
moles, mass, number of particles, concentration, volume of solution;
CC2.06 - solve
problems involving stoichiometric relationships in balanced chemical equations;
CC2.08 - prepare
aqueous solutions, using appropriate concentration units, and accurately dilute
a stock solution to a specified lower concentration;
CC3.01 - give
examples of everyday situations in which an understanding of quantitative
relationships of substances is important;
CC3.02 - explain why
it is important to ensure accuracy in the concentration of certain solutions;
SIS.01 - demonstrate
an understanding of safe laboratory practices by selecting and applying
appropriate techniques for handling, storing and disposing of laboratory
materials and using appropriate personal protection;
SIS.02 - select
appropriate instruments and use them effectively and accurately in collecting
observations and data;
SIS.03 - demonstrate
the skills required to plan and carry out investigations using laboratory
equipment safely, effectively, and accurately;
SIS.04 - demonstrate
a knowledge of emergency laboratory procedures;
SIS.05 - select and
use appropriate numeric, symbolic, graphical, and linguistic modes of
representation to communicate scientific ideas, plans and experimental results;
SIS.07 - express the
result of any calculation involving experimental data to the appropriate number
of decimal places or significant figures;
SIS.08 - select and
use appropriate SI units;
SIS.09 - identify
and describe science and technology-based careers related to the subject area
under study.
·
Knowledge of the
definition and components of a solution, as well as how to apply mathematical
ratios effectively and accurately
·
Note-taking
skills
·
Gather materials
for the lab activity: balances, weighing boats, adequate number of volumetric
flasks, burettes, pipettes, Erlenmeyer flasks, tap-water, distilled water, salt
solution, solid soluble ionic compounds e.g., potassium nitrate, copper(II)
sulphate, ammonium carbonate. If possible, use micro-chemistry equipment. If
possible, use a spectrophotometer or lab-interfaced colorimeter.
·
Organize
instruction sheets for using various pieces of equipment, preparing solutions
from solids, serial dilution, measuring absorbance, and generating a
calibration curve.
·
Prepare problems
on concentration, dilution, and preparing and/or using calibration curves.
Include both Canadian and global industries and other settings in these
problems.
2.2.1 Student
Activity: Students observe proper techniques for using laboratory
equipment, as demonstrated by teacher. Using a set of prepared notes and their
own observations, students practise measuring different volumes of solution and
liquid for a titration set up, e.g., set up a burette, use a pipette to fill
material into an Erlenmeyer flask. Students participate in a peer assessment of
the technique.
Teacher Facilitation: The teacher demonstrates proper techniques for
use of a variety of lab equipment, e.g., burette, pipette, volumetric flask for
dilution, volumetric flask for making a solution from solid. Provide equipment
for students to set-up titration apparatus using tap-water and/or table salt
solution for practice.
2.2.2 Student
Activity: In groups of two or three, students follow an instruction sheet
to prepare a solution from solid, e.g., copper(II) sulphate, which they then
sequentially dilute to a specified concentration. They determine the
concentrations of all three solutions using given formulae and ratios. They
demonstrate proper lab safety and techniques, as practised in the previous
activity, e.g., they can calculate the concentration of the first solution
using the given formula: concentration = mass/volume. They then determine the
dilutions through ratios, e.g., 1:1 means the second concentration is half the
first concentration) and record this data on their own results sheet. They also
convert the mass concentration to mole concentration from their knowledge of
the link between mass and moles.
Teacher Facilitation: The teacher reminds students of the safe
handling and disposal procedures or the chemicals being used and provides an
instruction sheet for students to review, for preparing a solution from solid
and for serial dilution. Monitor the lab activity for proper technique by
students. The teacher introduces the idea of molar concentration, as
investigated in the lab and provides students with the molar concentration
formula.
2.2.3 Student
Activity: Students complete notes from teacher-led lesson on concentration and
the concept of dilution. In groups or individually, they complete problems
including some that require manipulating equations to solve for an unknown.
Teacher Facilitation: The teacher conducts a lesson on concentration
and dilution. The teacher reviews the molar concentration formula and
introduces the dilution formula (C1V1 = C2V2).
Problems are assigned, e.g., textbook, problems sheet on concentration and
dilution quantities, including those that require manipulating formulae.
2.2.4 Student Activity: Students design
and conduct a procedure to prepare a standard solution and prepare various
concentrations by dilution. Following teacher instruction, students prepare and
conduct a procedure to measure absorbance and generate an experimental
calibration curve. Again they demonstrate proper lab technique and safety
procedures. They predict a non-standard concentration using the curve.
Teacher Facilitation: The teacher reminds students of the safe
handling and disposal procedures for the chemicals being used. Assign standard
solution for students to prepare, from dilution. Approve and provide
suggestions for improvement on procedure for this before allowing students to
continue with experiment. Instruct on generating a calibration curve for
absorbance. The teacher may demonstrate the procedure to clarify further.
Prepare a solution of unknown concentration, of which students determine
concentration, using the calibration curve and provide probe-ware, if possible,
for calibration curve.
· Students are assessed on four assignments in this activity: lab safety and technique (both titration set-up and preparing solutions), results sheet (for preparing standard solution and serial dilutions), procedure for preparing solutions for a calibration curve and the calibration curve itself. Students may continue to be assessed on their ability to work independently and in groups, participate effectively and follow instructions (Learning Skills). Students complete concentration and dilution problems and may be formally assessed on these problems after this activity or, after further practice, at the end of Act 2.3.
· Lab Technique (I), Results Sheet (I, C), Problem Set (K/U, MC)
·
Students may be
sensitive to some or all of the chemicals that are used in this activity.
Adaptations include not using these particular chemicals, or allowing students
to do dry labs instead.
Chemical
Calculations (worksheets and problems)
– www.tntech.edu/www/acad/chem/jackson/notes7.htm
–
www.mhhe.com/catalogs/sem/chemistry/
–
www.wpbschoolhouse.btInternet.co.uk/page04/4_73calcs.htm
–
www.tntech.edu/www/acad/chem/jackson/notes7.htm
–
www.mhhe.com/catalogs/sem/chemistry/
–
www.wpbschoolhouse.btInternet.co.uk/page04/4_73calcs.htm
Time: 5 hours
Students have already reviewed the meaning of
atomic subscripts in chemical formulae when starting the unit. In this
activity, students are introduced to both the meaning of coefficients in
balanced chemical reactions, using manipulatives, and the basic theory of
stoichiometry. This activity introduces students to the basics of percentage
yield, with an emphasis on the stoichiometry. Students use given theoretical
data and use their own experimental data to determine percentage yield of a
reaction. Using the experiment as a starting point, students discuss the
reasons for observing the difference between theoretical and actual yield, the
importance of percentage yield in real-life applications, e.g., the Haber
process, and methods of modifying the procedure to increase actual yield. Their
understanding is reinforced by a series of problems and experiments.
Strand(s): Chemical Calculations
Learning Expectations
CCV.01 - demonstrate
an understanding of the mole concept as well as of quantitative relationships
in chemical reactions;
CCV.02 - use
techniques of quantitative analysis in the preparation of standard solutions
and solve problems involving the analysis of quantities in chemical reactions,
using both theoretical and experimentally measured quantities;
CCV.03 - explain the
importance of quantitative chemical relationships in industry and in everyday
life;
CC1.02 - explain how
the following variables are related: coefficients in balanced chemical
equations, quantities in moles, mass and number of particles;
CC1.03 - identify
sources of experimental error that would explain a percentage yield other than
100 per cent;
CC2.01 - use
appropriate scientific vocabulary to communicate ideas related to
stoichiometry;
CC2.02 - conduct
quantitative analyses, using correctly and accurately the following
instruments: pipette, burette, volumetric flask, spectrophotometer, electronic
balance;
CC2.05 - solve
problems involving relationships among the following variables: quantities in
moles, mass, number of particles, concentration, volume of solution;
CC2.06 - solve
problems involving stoichiometric relationships in balanced chemical equations;
CC2.07 - calculate
percentage yield in a chemical reaction using experimental data, and identify
sources of error;
CC2.08 - prepare
aqueous solutions, using appropriate concentration units, and accurately dilute
a stock solution to a specified lower concentration;
CC3.02 - explain why
it is important to ensure accuracy in the concentration of certain solutions;
CC3.03 - explain why
the profitability of an industry depends in large part on its ability to
maximize percentage yield of its products;
SIS.01 - demonstrate
an understanding of safe laboratory practices by selecting and applying
appropriate techniques for handling, storing and disposing of laboratory
materials and using appropriate personal protection;
SIS.02 - select
appropriate instruments and use them effectively and accurately in collecting
observations and data;
SIS.03 - demonstrate
the skills required to plan and carry out investigations using laboratory
equipment safely, effectively, and accurately;
SIS.04 - demonstrate
a knowledge of emergency laboratory procedures;
SIS.05 - select and
use appropriate numeric, symbolic, graphical, and linguistic modes of
representation to communicate scientific ideas, plans and experimental results;
SIS.07 - express the
result of any calculation involving experimental data to the appropriate number
of decimal places or significant figures;
SIS.08 - select and
use appropriate SI units;
SIS.09 - identify
and describe science and technology-based careers related to the subject area
under study.
·
Proper technique
in using laboratory equipment
·
Chemical formulae
for simple ionic and covalent compounds
·
Ability to
manipulate and calculate percentages effectively
·
Gather materials
for lab activity: balances (electronic, if possible), pre-made measuring boats,
adequate number of beakers, spatulas and stirring rods, distilled water, solid
soluble ionic compounds that generate a solid during double displacement
reaction, e.g., copper(II) sulphate and dilute calcium chloride.
·
Some of the
chemicals used may be toxic or contain heavy metals. Follow board policy for
the safe handling and disposal of all materials.
·
Prepare problems
on mole ratios and percentage yield. Include both Canadian and global
industries and other settings in these problems, e.g., percentage yield in
mining industries.
·
Research and
prepare information on importance of percentage yield in real-life
applications, to assist students in discussion. Include both Canadian and
global content in this information.
·
Prepare Standard
Results Sheet for Act 2.3.3.
2.3.1 Student
Activity: Students use models to simulate chemical reactions and realize
that atoms for each element must be equal on both sides of a chemical reaction
(Law of Conservation of Mass). They use these models to determine the
relationship between coefficients in a balanced chemical reaction and mole
ratios, e.g., if two NO particles react, it translates to twice Avogadro’s
number, which means two moles.
Teacher Facilitation: The teacher provides models, e.g., molecular
models, paper models, marshmallow/toothpick models, and an instruction sheet to
guide students with activity. The teacher then presents a lesson that
summarizes the meaning of balanced chemical reactions, e.g., the meaning of
coefficients and subscripts in a balanced chemical reaction; how to translate
these into moles.
2.3.2 Student
Activity: Students participate in a class discussion of the importance of
mole ratios in industry. They complete problems on mole ratios.
Teacher Facilitation: The teacher leads students in a discussion on
the importance of mole ratios in industry and other real-life applications.
Problems on mole ratios in balanced chemical reactions, e.g., lab stations,
group problem-assignment, textbook problems, are assigned.
2.3.3 Student
Activity: Students complete a Standard Results Sheet (see Appendix C) to
determine percentage yield of a double-displacement chemical reaction, e.g.,
copper (II) sulphate with calcium chloride. When conducting the reaction, they
demonstrate proper lab safety procedures and technique. They discuss why the
actual yield is not the same as the expected yield and how this is important in
industry. As an extension, students use their percentage yield to predict the
amount of reactants needed to generate a required amount of product, and
conduct an experiment to verify their prediction.
Teacher Facilitation: The teacher provides a Standard Results Sheet
and expected yield so that students may compare this to their actual yield, in
order to generate a percentage yield. The teacher guides the students through a
discussion of the difference between expected and actual yield and its
importance in industry. For the lab extension, either allow students to
determine their own amount of required product or assign a required amount of
product.
2.3.4 Student Activity: Students complete
problems on percentage yield.
Teacher Facilitation: The teacher provides students with problems on
percentage yield, e.g., lab stations, group problem assignment, textbook
problems.
· By the time students commence Activity 2.3, they have had extensive assessment on their ability to work in groups and individually in labs and in other class activities. It would be appropriate to shift the focus of assessment on ability to solve theoretical problems, lab safety and technique and accuracy of results.
· Problem Sets (K/U, MC), Results Sheet (I, C)
·
Some students may
be sensitive to some or all of the chemicals that are used in this activity.
Adaptations include not using these particular chemicals, or allowing students
to use previously collected data.
Percentage
Yield (chemistry websites for worksheets and examples):
– antoine.fsu.umd.edu/chem/senese/101/moles/slides/tsld020.htm
–
www.scidiv.bcc.ctc.edu/wv/ex/percent-yield.html
–
learn.chem.vt.edu/tutorials/stoichiometry/percentyield.html
–
www.westminster.net/faculty/dingle/hworkyield.doc
–
www.ucdsb.on.ca/tiss/stretton/chem1/stoich7.htm
Time: 2 hours
In this activity,
students are introduced both qualitatively and quantitatively to percentage
composition of various compounds and the importance of this concept in various
fields of applied chemistry, e.g., geochemistry. They calculate percentage
composition of a compound using both theoretical and experimental values.
Strand(s): Chemical Calculations
Learning
Expectations
CCV.02 - use
techniques of quantitative analysis in the preparation of standard solutions
and solve problems involving the analysis of quantities in chemical reactions,
using both theoretical and experimentally measured quantities;
CC2.04 - calculate
percentage composition of a compound using experimental data or its chemical
formula;
SIS.05 - select and
use appropriate numeric, symbolic, graphical and linguistic modes of
representation to communicate scientific ideas, plans and experimental results;
SIS.07 - express the
result of any calculation involving experimental data to the appropriate number
of decimal places or significant figures;
SIS.08 - select and
use appropriate SI units;
SIS.09 - identify
and describe science and technology-based careers related to the subject area
under study.
·
Knowledge of effectively
manipulating and applying percentages
·
Prepare problems
on chemical composition of compounds.
·
Review
End-of-Unit task so that students may prepare a procedure for approval.
2.4.1 Student
Activity: Students participate in a teacher-led lesson on percentage
composition calculations. They complete problems on percentage composition and
discuss the importance of percentage composition to industrial applications,
e.g., impurities in mineral ores.
Teacher Facilitation: The teacher introduces the End-of-Unit Task.
The teacher instructs on percentage composition in chemical compounds and
provides practice problems through a variety of strategies, e.g., lab stations,
group problem-assignment, textbook problems, using both theoretically and
experimentally measured quantities. The teacher then leads a discussion about
the practical applications of percentage composition.
· Since this activity does not have a lab component, students are assessed on their ability to solve theoretical problems and practical problems, using previously collected data.
· Problem Set (K/U, MC)
·
As an extension,
the teacher may combine problems on stoichiometry and percentage composition.
The
Chemistry and Processing of Jamaican Bauxite
– http://wwwchem.uwimona.edu.jm:1104/lectures/bauxite.html
Chemical
Calculations (worksheets and problems):
–
www.tntech.edu/www/acad/chem/jackson/notes7.htm
–
www.mhhe.com/catalogs/sem/chemistry/
–
www.wpbschoolhouse.btInternet.co.uk/page04/4_73calcs.htm
–
www.tntech.edu/www/acad/chem/jackson/notes7.htm
–
www.mhhe.com/catalogs/sem/chemistry/
–
www.wpbschoolhouse.btInternet.co.uk/page04/4_73calcs.htm
Time: 4 hours
Students combine
their knowledge of moles, stoichiometry, solubility, and concentration to
experimentally determine the amount of soluable compound dissolved in a
solution. This assignment, along with a unit test, constitutes the summative
evaluation of this unit.
Strand(s): Chemical Calculations
Learning
Expectations
CCV.01 - demonstrate
an understanding of the mole concept as well as of quantitative relationships
in chemical reactions;
CCV.02 - use
techniques of quantitative analysis in the preparation of standard solutions
and solve problems involving the analysis of quantities in chemical reactions,
using both theoretical and experimentally measured quantities;
CC1.01 - define the
mole concept and demonstrate an understanding of its usefulness in the analysis
of quantities involved in chemical reaction;
CC1.02 - explain how
the following variables are related: coefficients in balanced chemical
equations, quantities in moles, mass and number of particles;
CC1.03 - identify
sources of experimental error that would explain a percentage yield other than
100 per cent;
CC2.01 - use
appropriate scientific vocabulary to communicate ideas related to
stoichiometry;
CC2.02 - conduct
quantitative analyses, using correctly and accurately the following
instruments: pipette, burette, volumetric flask, spectrophotometer, electronic
balance;
CC2.03 - calculate
the molecular mass and molar mass of a compound with the aid of the periodic
table;
CC2.04 - calculate
percentage composition of a compound using experimental data or its chemical
formula;
CC2.05 - solve
problems involving relationships among the following variables: quantities in
moles, mass, number of particles, concentration, volume of solution;
CC2.08 - prepare
aqueous solutions, using appropriate concentration units, and accurately dilute
a stock solution to a specified lower concentration;
SIS.01 - demonstrate
an understanding of safe laboratory practices by selecting and applying
appropriate techniques for handling, storing and disposing of laboratory
materials and using appropriate personal protection;
SIS.02 - select
appropriate instruments and use them effectively and accurately in collecting
observations and data;
SIS.03 - demonstrate
the skills required to plan and carry out investigations using laboratory
equipment safely, effectively, and accurately;
SIS.04 - demonstrate
a knowledge of emergency laboratory procedures;
SIS.05 - select and
use appropriate numeric, symbolic, graphical, and linguistic modes of representation
to communicate scientific ideas, plans and experimental results;
SIS.07 - express the
result of any calculation involving experimental data to the appropriate number
of decimal places or significant figures;
SIS.08 - select and
use appropriate SI units.
·
Knowledge of
chemical formulae and percentage calculations
·
Review student
procedure, assigned in Activity 2.5.1, before allowing students to proceed on
their own.
·
Prepare a number
of non-standard solutions of copper(II) sulphate. (Other soluble ionic
compounds may be used.)
·
Gather materials
for lab activity, as required by student procedure.
·
Prepare a unit
test covering Avogadro’s number, moles, mass, molar mass, percentage
composition, concentration, dilution, and percentage yield.
·
Prepare materials
for practical component of unit test, e.g., concentrated solutions of
copper(II) sulphate and iron(III) nitrate.
·
Gather equipment
for practical component, e.g., pipettes of various volume, volumetric flasks of
various volumes.
2.5.1 Student
Activity: Students design and conduct an experiment to determine the amount
of soluable compound (e.g., copper (II) sulfate) in a unknown, non-standard
solution by using a double displacement reaction. Throughout, they demonstrate
proper lab safety procedures and technique.
Teacher Facilitation: The teacher provides a different non-standard
solution of a soluable ionic compound for each student of the class. Several
different compounds may be used. The teacher also makes available compounds
that students can use to produce solutions of known concentrations for their
double displacement reactions. The teacher should approve student procedures
prior to performance and make suggestions where necessary. A possible procedure
might involve reacting the unknown copper (II) sulfate solution with a solution
of sodium carbonate of known concentration (prepared by the student). The
resulting precipitate is then filtered, dried, and massed. From there, the
unknown amount of soluble compound is determined.
· The activity is assessed on four components: the procedure used to determine percentage composition, lab safety and technique during the experiment, use of an effective data recording and results sheet, and accuracy of results in determining concentration of solution. The unit test will focus primarily on knowledge but will include some practical components as suggested above.
· Student Designed Procedure (K/U, I, C, MC), Unit Test (K/U, MC, I)
·
Some students may
be sensitive to some or all of the chemicals that are used in this activity.
Adaptations include not using these particular chemicals.
Chemistry
Education Sites – science.uniserve.edu.au/disc/chem/schools.html
Links to
Chemistry Online – antoine.fsu.umd.edu/chem/senese/101/reverse-links.shtml
Woodrow Wilson
Leadership Programme in Chemistry – www.woodrow.org/teachers/chemistry/
Name: Date:
Time started:
Time completed:
1. The
molecular formula of the chemical: ________________________
|
Column A |
Column B |
Column C |
Column D |
|
|
|
|
|
|
|
|
|
|
|
|
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|
|
|
|
Total |
|
|
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|
molecular |
|
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|
mass |
|
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= |
2. Column A: symbol of element
Column B: average atomic mass of element (calculated to 3 decimal places)
Column C: number of atoms of element denoted
by the subscript, e.g., C2H4 has two carbons and
4 hydrogens
Column D: total atomic mass = column B × column C (calculated to 3 decimal places)
Total molecular mass: add all values in column D (calculated to 3 decimal places)
3. The
total molecular mass of the compound is ____________________ g/mol.
Signature: _______________________
Name: Date:
Time started:
Time completed:
1. Chemical A name: ____________________
Chemical A formula: __________________
2. Chemical B name: ____________________
Chemical B formula: __________________
3. Expected yield, as provided by authority:
_______________________ g
4. Actual mass (reading
1): __________________________g (read
to 2 decimal places)
(reading 2): __________________________g (read to 2 decimal places)
(reading 3): __________________________g (read to 2 decimal places)
5. Average actual mass:
_____________________________g (calculated
2 decimal places)
6. Percentage yield:
_________________________________%
(calculate with the following
formula [(#5 - #3)/3] × 100)
Signature:
_________________
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