9C.2.1.3 Chemical Reactions
Classify chemical reactions as double replacement, single replacement, synthesis, decomposition or combustion.
Use solubility and activity of ions to determine whether a double replacement or single replacement reaction will occur.
Relate the properties of acids and bases to the ions they contain and predict the products of an acid-base reaction.
Balance chemical equations by applying the laws of conservation of mass and constant composition.
Use the law of conservation of mass to describe and calculate relationships in a chemical reaction, including molarity, mole/mass relationships, mass/volume relations, limiting reactants and percent yield.
Describe the factors that affect the rate of a chemical reaction, including temperature, pressure, mixing, concentration, particle size, surface area and catalyst.
Recognize that some chemical reactions are reversible and that not all chemical reactions go to completion.
Overview
MN Standard in Lay Terms
Combustion and all other chemical processes consist of the interaction of substances such that the total mass of material after the reaction is exactly the same as before the reaction, since atoms must be conserved.
There are five general categories of reactions: single replacement, double replacement, synthesis, decomposition, and combustion.
The configuration of electrons in atoms determines what reactions can occur between atoms, how much energy is required to get the reaction to happen, and how much energy is released in the reaction.
The rates at which reactions occur depend on how often the reactants collide with one another, and so depend on the concentration and speed (temperature) of the reactants.
Big Idea
Students should be able to balance chemical reactions as well as determine what type of reaction is being studied and whether or not that reaction will go forward.
A thorough understanding of molar mass and mole relationships will be used to solve stoichiometric problems including limiting reactants and determining percent yields.
Students should understand that different reactions proceed forward at different rates and be able to describe the factors that affect the rate of a reaction.
Students should understand that simply putting two or more chemicals together does not mean a reaction will occur. Some particles are more effective at interacting than others.
Combustion and all other chemical processes consist of the interaction of substances such that the total mass of material after the reaction is exactly the same as before the reaction.
MN Standard benchmarks
9C.2.1.3.1 Classify chemical reactions as double replacement, single replacement, synthesis, decomposition, or combustion.
9C.2.1.3.2 Use solubility and activity of ions to determine whether a double replacement or single replacement reaction will occur.
9C.2.1.3.3 Relate the properties of acids and bases to the ions they contain and predict the products of an acid-base reaction.
9C.2.1.3.4 Balance chemical equations by applying the laws of conservation of mass and constant composition.
9C.2.1.3.5 Use the law of conservation of mass to describe and calculate relationships in a chemical reaction, including molarity, mole/mass relationships, mass/volume relations, limiting reactants, and percent yield.
9C.2.1.3.6 Describe the factors that affect the rate of a chemical reaction, including temperature, pressure, mixing, concentration, particle size, surface area, and catalyst.
9C.2.1.3.7 Recognize that some chemical reactions are reversible and that not all chemical reactions go to completion.
The Essentials
A Framework for Science Education (preliminary draft) - National Research Council (NRC)
page 3-10
PS1:
Curriculum Topic Study Guide - Matter: pages 157-173
Chemical Bonding (page 160)
Chemical Properties and Change (page 161)
Conservation of Matter (page 163)
Nuclear Chemistry (page 168)
Physical Science - Content Standard B (essay page 177 for development of)
Chemical Reactions (page 179)
Chemical reactions
12BPS3.1 Chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. Complex chemical reactions involving carbon-based molecules take place constantly in every cell in our bodies.
12BPS3.2 Chemical reactions may release or consume energy. Some reactions such as the burning fossil fuels release large amounts of energy by losing heat and by emitting light. Light can initiate many chemical reactions such as photosynthesis and the evolution of urban smog.
12BPS3.3 A large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Radical reactions control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.
12BPS3.4 Chemical reactions can take place in time periods ranging from the few femtoseconds (10 -15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. Reaction rates depend on how often the reacting atoms and molecules encounter one another, on the temperature, and on the properties - including shape - of the reacting species.
12BPS3.5 Catalysts, such as metal surfaces, accelerate chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes.
Making Sense of Secondary Science - research into children's ideas
Chapter 10: Chemical Change (pages 85-91)
- Benchmarks of Science Literacy:
Physical Setting: Structure of Matter, pages 75-80
An important kind of reaction between substances involves the combination of oxygen with something else-as in burning or rusting. 4D/M6b*
No matter how substances within a closed system interact with one another, or how they combine or break apart, the total mass of the system remains the same. 4D/M7a*
The idea of atoms explains the conservation of matter: If the number of atoms stays the same no matter how the same atoms are rearranged, then their total mass stays the same. 4D/M7b
Substances react chemically in characteristic ways with other substances to form new substances with different characteristic properties. 4D/M11** (NSES)
If samples of both the original substances and the final substances involved in a chemical reaction are broken down, they are found to be made up of the same set of elements. 4D/M12**
The idea of atoms explains chemical reactions: When substances interact to form new substances, the atoms that make up the molecules of the original substances combine in new ways. 4D/M13**
The rate of reactions among atoms and molecules depends on how often they encounter one another, which is affected by the concentration, pressure, and temperature of the reacting materials. 4D/H9a
Some atoms and molecules are highly effective in encouraging the interaction of others. 4D/H9b
Research Base: Structure of Matter - chemical changes
4d: Structure of Matter - research on student thinking about the nature of matter and chemical changes
American Association for the Advancement of Science Atlas
The Physical Setting: Conservation of Matter 4D (blue pages 56-57)
The Physical Setting: Chemical Reactions 4D (blue pages 60-61)
Historical Perspectives: The Chemical Revolution 10F (green pages 80-81)
Historical Perspectives: Splitting the Atom 10G (green pages 82-83)
Chapter 2 Science Content
Physical Science - Matter
Changes in Matter - pages 28-29
Common Core Standards
2010 Literacy Standards - Reading Benchmarks: Literacy in Science and Technical Subjects 6-12
Integration of Knowledge and Ideas Benchmark 11.13.7.7 Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., quantitative data, video, multimedia) in order to address a question or solve a problem.
Misconceptions
Student thinking tends to be dominated by the obvious features of the change. (explosion, fire, etc.)
Many students do not view chemical changes as interactions. They do not understand that substances can be formed by the recombination of atoms in the original substances. (pg 60 Blue Atlas of Sci. Lit)
Addressing Misconceptions NSTA articles on student misconceptions. One of the three specifically addresses the conservation of mass and has a classroom lesson laid out as an example for teachers.
On the Web: Overcoming Misconceptions - NSTA has compiled resources on how teachers can address misconceptions on this website.
Vignette
Ms. Z dims the has the students gather around, dims the lights and lets a soap bubble slowly rise. She extends a burning match on a stick and WHOOSH, the bubble ignites into a glowing ball of flame. The kids jump back and squeal with amazement and enthusiasm, glad to be wearing the goofy goggles. "What just happened?" she asks her class as they settle back into their seats. The class has worked through basic balancing of equations but Ms. Z uses this demonstration to introduce the idea of predicting products from given reactants. Using the students' curiosity, she can talk about what happens when different chemicals get mixed together. Why do some combinations blow up and others do nothing?
For the next couple of class periods, students learn about the different types of reactions and how knowing the type can help predict products. After working on the theory, Ms. Z has the students go through a series of lab stations illustrating real life reactions for each category. Students are encouraged to make careful observations before, during and after the reactions to look for evidence of chemical changes that support theories they have been studying. Ms. Z reminds them that part of the final assessment will be a lab practical where they will be given various reactants and they must produce a given substance.
Using water treatment and heavy metals as an example, Ms. Z next introduces the idea of quantities in chemical equations. She reviews the unit analysis method from the start of the year (NOSE Benchmark 9.1.3.4.5.Demonstrate how unit consistency and dimensional analysis can guide the calculation of quantitative solutions and verification of results).and models how to solve stoichiometric problems for the class. (Geometry & Measurement Benchmark 9.3.1.3) Knowing this is a crucial component of an introductory class and can take a while for students to master, she has prepared several handouts with practice problems of varying levels of difficulty to make sure all students are making progress and being challenged.
Many of the problems she uses are real life scenarios. These problems are less listing of numbers and more reading to model how science approaches problems. One example the students enjoy is the cleaning of carbon dioxide out of the air using the scene from Apollo 13. Ms. Z also uses this to introduce the nature of science and engineering and the idea of solving problems within given constraints. (NOSE Benchmark 9.1.3.3. Describe how values and constraints affect science and engineering.)
As the problems get more complex, students are encouraged to collaborate with one another. Students finish the unit in the computer lab using the PHET simulation on limiting reactants before being given a final assessment. This requires that students complete, balance and determine specific quantities of reactants or products for given reactions including those studied in lab. (kinetics and equilibrium may be delayed and does not necessarily need to follow immediately after stoichiometry)
Resources
Instructional Suggestions/Options
1. Videos - Online videos can be a great way to engage students at the start of a unit. A google search of key words in the content area can yield a variety of demonstration sites as well as full length videos.
a. Mr. Kent's Chemical Demonstrations - Several pages of well done you tube videos of various reactions to show using an LCD when materials are too dangerous or costly to perform experiments in class.
b. Exploscience.com - Dynamic Chemistry- This site has a series of videos in one place showing several chemical reactions in action. It could be used to replace demonstrations if materials are not available or safety is an issue.
c. World of Chemistry Series - These videos are not modern but give a good foundation of basic information after the class has had some experience with the content. It can be used as a summary of the unit or possible review. Students could come up with a series of questions or use worksheets.
i.Molecules in Action - collision theory and equilibrium
Benchmarks 9C.2.1.3.6 and 9C.2.1.3.7
ii.Driving Forces - energy and entropy changes Benchmark 9.2.1.2.4
2. Science Literacy: Chemmatters - Published by the American Chemical Society, has relevant, fast reading articles to tie topics in the classroom to the real world of students. Teachers' guides with questions and additional background information are also available.
a. Hollywood's Special Effects
b. Biomimicry - Where Chemistry Lessons Come Naturally - page 15 Benchmark 9.1.1.1.2
3. NSTA series of Formative Assessment Probes
Uncovering Student Ideas in Science - Volume 4 pages 23-29 and pages 30-37
Burning Paper Benchmark 9.2.1.2.2 and 9C.2.1.3.4 and 5
Nails in a Jar Benchmark 9.2.1.2.2 and 9C.2.1.3.4 and 5
4. Scope and Sequence
see Benchmarks in Scientific Literacy (Section F: Understanding Fire)
5. The "Best Practices" of Science Teaching - Many of the "so-called best practices" are summarized and examples are given in the chapter "Guided inquiry in the science classroom" by Minstrell, J. & Kraus, P. found in How Students Learn: History, Mathematics, and Science in the Classroom. (M. Suzanne Donovan and John D. Bransford, Editors) Washington, DC: National Research Council (2005). Other best practices are to be found in Robert Marzano's Classroom Instruction that Works.
Suggested Labs and Activities
1. Common Labs for this unit include (Good Source is Flinn Topic Labs)
a. Types of Reactions Lab (be sure to include visual, identifiable changes for analysis)
b. Cycling of Copper Lab - several versions available on google; safety - must have fume hood!!!
c. Conservation of Matter Lab - several styles available
2. Predict the amounts of products and leftovers after reaction using the concept of limiting reactant, predict the initial amounts of reactants given the amount of products and leftovers using the concept of limiting reactant, translate from symbolic (chemical formula) to molecular (pictorial) representations of matter. Benchmarks 9C.2.1.3.4 and 9C.2.1.3.5
3. Explore what makes a reaction happen by colliding atoms and molecules. Design experiments with different reactions, concentrations, and temperatures. When are reactions reversible? What affects the rate of a reaction? Benchmarks 9C.2.1.3.6 and 9C.2.1.3.7
4. Watch a reaction proceed over time. How does total energy affect a reaction rate? Vary temperature, barrier height, and potential energies. Record concentrations and time in order to extract rate coefficients. Do temperature dependent studies to extract Arrhenius parameters. This simulation is best used with teacher guidance because it presents an analogy of chemical reactions. Benchmarks 9C.2.1.3.6 and 9C.2.1.3.7
The above simulation sites could be used for introductory inquiry by the students, as well as a review where students would predict results and check for accuracy. Several lessons are available for teachers to edit to meet classroom needs.
Additional resources
This site has 15 minute podcasts for every topic in a general chemistry course. They are 15 minute segments posted on youtube for students to use independently or as a tutorial supplement for classroom instruction.
ChemTours developed specifically for Chemistry, 2nd Edition. These use animation and interactive exercises to help develop your understanding of fundamental concepts.
Mark Bishop's Online Chemistry Textbook
Includes lessons, powerpoints, and tutorials along with typical written text.
Online Quizzes From Modern Chemistry, by Davis & Metcalfe
Vocabulary/Glossary
- chemical reaction - a dissociation, recombination, or rearrangement of atoms
- double displacement - a reaction in which two reactants trade fragments: AB + CD = AC + BD
- acid-base reaction - A chemical change in which one compound aquires H+ from another. The compound that receives the hydrogen ion is the base; the compound that surrenders it is an acid.
- single displacement - a reaction in which an element replaces an ion in a compound.
- synthesis/combination - A reaction in which two or more substances are chemically bonded together to produce a product. For example, 2 Na(s) + Cl2(g) → 2 NaCl(s) is a combination reaction.
- decomposition - A reaction in which a compound is broken down into simpler compounds or elements.
- endothermic - process in which the system absorbs energy from the surroundings
- solubility - ability to dissociate in a solvent
- precipitate - An insoluble substance that has been formed from substances dissolved in a solution
- activity series - a list of metallic elements, with the strongest metals at the top and the weakest at the bottom. The strongest metal is said to be the most reactive metal. The weakest metal is said to be the least reactive
- limiting reactant - The reactant that will be exhausted first.
- stoichiometry - The study of the relationships between amounts of products and reactants
- percent yield - Percent yield equals experimental yield divided by theoretical yield times 100%.
- reversible- reaction that goes both forward and backward under the same conditions
- rate of reaction - measure of the disappearance or appearance of reactants or products in a reaction
- reactant - Substances initially present in a chemical reaction.
- product - The compounds that are formed when a reaction goes to completion.
- catalyst - Substance that speeds up a chemical process without actually changing the products of reaction.
- combustion - When substances combine with oxygen and release energy
MN Math Benchmarks
9.2.1.4 Obtain information and draw conclusions from graphs of functions and other relations (potential energy diagrams)
9.3.1.5 Make reasonable estimates and judgements about the accuracy of values resulting from calculations involving measurements (conservation of mass lab)
Assessment
Assessment of Students
1. If an energy term appears on the right side of a chemical equation the reaction must be:
a. complete b. incomplete c. exothermic d. endothermic
2. The products formed during a combustion reaction include:
a. H2O + CO2 b. H2 + CO2 c. C + H2 + O2 d.not enough information given
3. What mass of sodium must be added to water to produce 275 grams of sodium hydroxide?
2Na + 2H2O → 2NaOH + H2
4. 10 moles of hydrogen gas are reacted with 3 moles of oxygen gas. How many moles of water will be formed? What reactant is in excess? How many moles of the excess will remain?
2H2 + O2 → 2H2O
6 moles water; hydrogen in excess by 4 moles (molar ratio math should be shown)
5. Copper reacts with silver nitrate but silver does not react with copper II nitrate. Explain how this statement is not contradictory.
The activity series shows that copper is more reactive than silver and therefore copper will replace silver in solution but silver cannot replace copper in solution as it is a less reactive metal.
Assessment of Teachers
A student says that the evidence of a chemical change was the steam coming from the reaction. How might this statement be correct? How might this statement be incorrect?
Students sometimes see steam and smoke as being the same. Be sure they understand the importance of new gases (smoke) versus energy released (steam). Word must be accurate when explaining reaction evidence.
Are acid -base reactions a separate "type" of reaction or should they be placed into one of the five classifications of reactions? Explain your answer.
They are a subtopic within the double displacement category. They get special attention during the study of acids and bases.
Differentiation
Struggling and At-Risk
Chemical reactions is highly interesting to many at-risk students as it can explore very visual, dynamic reactions.
Using demonstrations daily can engage most students and seeing them invites students to attend class regularly.
Mathematical relationships is typically not a strength. More than three steps in dimensional analysis can be a challenge - slow and repetitive helps.
Teaching Science to ELL - part 1 and 2 - NSTA journal The Science Teacher articles available for free on ELL language and learning.
The Sourcebook for Teaching Science - Strategies, Activities, and Instructional Resources
The science classroom is often a frustrating place for English language learners. Science has a complex vocabulary that is difficult even for native English speakers to learn. Difficulty learning English should not be confused with an inability to think scientifically. Many of the strategies that are useful for English language learners are effective for differentiating instruction for others.
Teaching Science to English Language Learners: Building on Students' Strengths - Can a student's cultural background support learning in science? Or is concentrating on the specialized vocabulary of science the best way to help English language learners learn science? This book addresses these and other pressing questions you face when working with students whose linguistic and cultural backgrounds, as well as their languages, are different from your own.
Anytime lessons and activities can be posted online ahead of time or shortly after help those students who struggle with note taking and organization.
Give choices for possible products rather than having them predict simply from reactants.
Given possible math limitations, extra time and guidance is necessary for any stoichiometry.
Short quizzes often rather than one exam is necessary for limited math processing students.
Cornell Notes
Parents/Admin
Administrators
Students should be actively engaged in various labs demonstrating the idea of new substances being formed during a chemical reaction. Administration should expect to see student work that predicts outcomes of from particular reactants and conclusions drawn from laboratory evidence.
Safety followed at all times, students have goggles on.