Unit Overview
Unit Overview
Formula Stoichiometry
Timeframe = 8 days
TEKS
FBISD Power Standards
112.35.C.CHE.7.A -
name ionic compounds containing main group or
transition metals, covalent compounds, acids, and bases, using International Union of
Pure and Applied Chemistry (IUPAC) nomenclature rules;
112.35.C.CHE.7.B -
write the chemical formulas of common polyatomic
ions, ionic compounds containing main group or transition metals, covalent compounds,
acids, and bases;
112.35.C.CHE.8.A -
define and use the concept of a mole;
112.35.C.CHE.8.B -
use the mole concept to calculate the number of
atoms, ions, or molecules in a sample of material;
112.35.C.CHE.8.C -
calculate percent composition and empirical and
molecular formulas;
Teacher to Teacher Notes
Resources
What should students know about Formula stoichiometry prior to
chemistry?
Resource
Beginning in 2010, Students in 8th grade were able to determine the
number of atoms of each element in chemical formulas containing
subscripts (8.5D), and recognize whether a chemical equation containing
coefficients is balanced or not and how that relates to the law of
conservation of mass (8.5F). They were only required to count atoms
and determine if the equation was balanced or not. Students who have
taken IPC should know that mass is conserved when substances
undergo chemical change and that the number and kind of atoms are the
same in the reactants and products (I.7C). Although, the term "mole" is
mentioned in the IPC textbook, it is not specifically emphasized in the
course. Students are introduced to the concept of mole and
stoichiometric calculations for the first time in chemistry.
What should students about Formula stoichiometry by the end of
this unit?
Student will define and use the mole ratios of atoms (C.8A) They will find
molar mass to make conversions among moles, mass, and number of
representative particles. They will calculate the molar mass of a
compound and calculate the number of moles of a compound from a
given mass of the compound. Students will find the mass of a compound
from a given number of moles of the compound and determine the
number of atoms or ions in a mass of a compound (C.8B). They will
know how to determine the percent composition of the components of
compounds and calculate the empirical and molecular formulas for
compounds (C.8C).
Assessment/Rubrics
 Molar Mass Exit Ticket--Stoich
Assessment/Rubrics
 Moles, Grams and Atoms Exit
Ticket--Stoich
Assessment/Rubrics
 CFA_Formulas Stochiometry
Instructional Resources
 Mole practice problems
Instructional Resources
 Moles Assessment--Stoich
Instructional Resources
 Naming and formula writing WS
 Practice - Molar Mass
Calculations--Stoich
 Rally Coach - Mole
What will students learn about Formula Stoichiometry after
chemistry?
Students will need the knowledge acquired in this unit to be able to
perform stoichiometric calculations, including determination of mass
relationships between reactants and products, calculation of limiting
reagents, and percent yield.
For those students taking AP chemistry, a basic understanding of
stoichiometry is required. At the AP level, thirty-five to forty percent of
the material taught will cover mass and volume relations. Emphasis is on
the mole concept, including empirical formulas and limiting reactants.
Vocabulary
Mole
Formula unit
Avogadro's number
Molar Mass
Mole Ratio
Empirical formula
Theoretical Yield
Molecular Formula
Gram formula mass
Naming compounds
Formula writing
Representative particles
Formula unit
Prefixes
Criss-cross
Note that the terms, molecular weight (M.W.) and formula weight (F.W.)
are older terms for what is now more correctly called the relative molar
mass and are not taught in this unit.
Molar mass is closely related to the relative molar mass of a compound,
to the older term formula weight, and to the standard atomic masses of
its constituent elements. However, it is not the same as the molecular
mass, which is the mass of one molecule (of a specific isotopic
composition) and is not directly related to the atomic mass, the mass of
one atom (of a specific isotope). You do not need to go into these
distinctions with your students, but be careful to use the term molar mass
correctly when teaching this unit.
Assessment
These standards will be tested on the Chemistry STAAR test. Chemistry
TEKS C.8B is a readiness standard, while TEKS C.8A and C.8C are
supporting standards in Reporting Category 3: Bonding and Chemical
Reactions.
Suggested Strategies
•
Homework and Practice
o Use white boards to practice stoichiometric calculations. As you
walk around the room, collect a few answers (especially those with
common mistakes). Once
everyone is finished and has shown you
their answer, hold the collected boards up and ask the class what the
student did right and wrong. If there was something the student did
wrong, ask the class how the student would correct this mistake. Be
mindful not to embarrass students during this process - keep the
original answer writer anonymous.
o If you have different levels of understanding in your class, use the
"Tiered lesson" for practice. Students who need to practice with mole
Calculations--Stoich
 The Mole PPT -- Stoich
 Moles WS
Lab
 Mole Ratios Lab--Stoich
ratios start with Set 1, students who are progressing in understanding
but need some assistance with stoichiometric calculations start with
Set 2, and students who need more of a challenge start with Set 3.
o Practice and reinforce individual steps of the process if students
are struggling. For instance, use the "Practice - calculating molar
mass" to reinforce that students first need to balance the equation and
find the molar mass of the reactants and products.
• Cooperative learning
o Peer tutoring - pair up students who are proficient with those who
are struggling and have them help each other practice. One way to do
this is by having students complete the "Rally coach - mole
calculations" in pairs. Be sure to explain and model thinking out loud
before writing their answers.
o
o Pass the question - Place students into groups and allow them to
write a challenge question for another group. When each group is
ready, they "pass the question" to another group. That group writes
out an answer (can use chalk on lab tables, white boards, or chart
paper). The group that wrote the question checks the other group's
answer and gives feedback.
• Setting Objectives and Providing Feedback
o Circulate among the students and observe and question them while
they are working.
o Provide direct and specific information to help students see and
learn how to correct errors
o Provide prompt feedback to strengthen a student's corrective action
and to affirm efforts.
o Write instructions on the board as well as say them aloud.
o Provide examples and models of what is expected of students.
o After they have the basic methodology down, let students come up
with a rubric/checklist for a good answer to stoichiometry
problems. Have them compare their checklist with others' and add to
their list. Have students use this to grade and correct their own
papers.
o If you see common mistakes during practice, make a paper showing
the answers with the common mistakes. Challenge students to circle
and correct the mistakes they see.
o Use exit tickets frequently to check for understanding and to allow
students to show their progress. Look under "resources" for
examples that may be used.
Notes
Remember to spiral in naming compounds and formula writing as you
teach this limit.
Process skills
This unit allows students to practice many of the process skills that were
learned earlier on. Continue to emphasize lab safety, scientific problem
solving, formula writing and naming for compounds. Students should
also do measurements and calculations using correct numbers of
significant figures and should use scientific notation when
appropriate. Remind students of the dimensional analysis techniques
that they learned previously and emphasize good problem solving
techniques.
Content Sources
Text Resources
CHEMISTRY: MATTER AND CHANGE (GLENCOE)
• C.2C: Section 11.1 Measuring Matter p. 308–312; Section 11.2 Mass
and the Mole p. 313–319; Section 11.3 Moles of Compounds p. 320–327;
Section 11.4 Empirical and Molecular Formulas p. 328–337
• C.11C: Section 12.1 What is stoichiometry? p. 352–357; Section 12.2
Stoichiometric Calculations p. 358–363;
MODERN CHEMISTRY (HOLT)
• C.2C: Section 3-3 Counting Atoms p. 75-85; Section 9-1 Introduction to
Stoichiometry p. 275-279; Section 9-2 Ideal Stoichiometric Calculations
p. 280-287; Section 9-3 Limiting Reactants and Percent Yield p. 288-294
• C.11C: Section 3-3 Counting Atoms p. 75-85; Section 9-1 Introduction
to Stoichiometry p. 275-279; Section 9-2 Ideal Stoichiometric
Calculations p. 280-287;
ExploreLearning Gizmos
www.explorelearning.com
• Stoichiometry
Resource
Assessment/Rubrics
 Molar Mass Exit Ticket--Stoich
Assessment/Rubrics
 Moles, Grams and Atoms Exit Ticket--Stoich
Assessment/Rubrics
 CFA_Formulas Stochiometry
Instructional Resources
 Mole practice problems
Instructional Resources
 Moles Assessment--Stoich
Instructional Resources
 Naming and formula writing WS
 Practice - Molar Mass Calculations--Stoich
 Rally Coach - Mole Calculations--Stoich
 The Mole PPT -- Stoich
 Moles WS
Lab
 Mole Ratios Lab--Stoich