AP Chemistry Guided Inquiry Activities for the Classroom PROFESSIONAL DEVELOPMENT AP® Chemistry Guided Inquiry Activities for the Classroom CURRICULUM MODULE For the redesigned course launching Fall 2[.]
Representing Chemical Equations and Stoichiometry
Renée Cole University of Iowa Iowa City, Iowa
• How do you represent what occurs in a chemical reaction?
• What determines how much product can be produced in a chemical reaction? For example, given the balanced chemical equation
2A + B → 3P: if six atoms of “A” react with two atoms of “B,” how many atoms of “P” can be made?
Stoichiometry is a fundamental concept in understanding the quantitative aspects of chemical reactions, which involves analyzing the relationships between reactants, products, and balanced chemical equations Despite its importance, stoichiometry is often perceived as challenging and sometimes tedious by both teachers and students Traditional teaching methods tend to focus on teaching a series of calculation algorithms, which may help students perform computations but can also lead to misconceptions about the underlying principles To foster a deeper understanding, educators should emphasize conceptual clarity alongside calculation skills in stoichiometry instruction.
The lack of conceptual understanding of stoichiometry is also problematic when students work with acid-base titrations, gas laws, and equilibrium concepts
Students require a solid understanding of stoichiometry to effectively solve numerical problems related to reactant and product quantities, symbolic equations, and particulate drawings Utilizing physical models like nuts and bolts can enhance comprehension of atomic and molecular arrangements, making abstract concepts more tangible and facilitating better learning.
LEGO® pieces, or other manipulatives is an additional strategy to help students better understand what a chemical equation represents This leads to a better understanding of stoichiometry.
Acid-Base Neutralization Reactions
Renée Cole University of Iowa Iowa City, Iowa
• How do you represent what occurs in a chemical reaction?
• What determines how much product can be produced in a chemical reaction? For example, given the balanced chemical equation
2A + B → 3P: if six atoms of “A” react with two atoms of “B,” how many atoms of “P” can be made?
Stoichiometry is a fundamental concept in understanding the quantitative aspects of chemical reactions, involving the relationships between reactants, products, and balanced chemical equations Although it is essential for mastering chemistry, many students and teachers find stoichiometry challenging and sometimes tedious Traditional teaching methods often focus on algorithms for calculations, which can help students perform computations but may also lead to misconceptions about the actual concepts To foster a deeper understanding, it is important to emphasize the core principles behind stoichiometry rather than just procedural steps, ensuring students grasp the significance of quantitative relationships in chemical reactions.
The lack of conceptual understanding of stoichiometry is also problematic when students work with acid-base titrations, gas laws, and equilibrium concepts
Students require a solid understanding of stoichiometry to effectively solve numerical problems involving reactant and product quantities, symbolic equations, and particulate representations Utilizing physical models, such as nuts, bolts, or other tangible objects, can enhance comprehension by providing a hands-on approach to visualizing chemical reactions and molecular interactions Mastering stoichiometry is essential for accurately calculating reactant and product amounts, which is fundamental in chemistry education and practical applications.
LEGO® pieces, or other manipulatives is an additional strategy to help students better understand what a chemical equation represents This leads to a better understanding of stoichiometry
X X Connections to the AP Chemistry Curriculum Framework
Understanding the interaction of atoms and molecules on the atomic level is fundamental in chemistry Balanced chemical equations are crucial because they indicate the precise number of particles involved in reactions and those produced afterward To accurately analyze chemical processes, it is essential to express the amount of a substance in terms of particles or moles, enabling a clearer understanding of reaction stoichiometry and chemical behavior.
Understanding essential knowledge 1.E.1 is crucial: physical and chemical processes can be symbolically represented, but these representations must accurately conserve all atoms involved Different types of symbols and diagrams can effectively illustrate how matter is conserved during chemical and physical changes, emphasizing the importance of atom conservation in scientific visualizations.
Understanding the conservation of atoms is essential for calculating the masses of substances involved in both physical and chemical processes In chemical reactions, new substances are formed, and their quantities depend on the number, types, and masses of the reactant elements, along with the efficiency of the transformation The coefficients in a balanced chemical equation indicate the relative numbers of particles consumed and produced during the reaction.
• Enduring understanding 3.A: Chemical changes are represented by a balanced chemical equation that identifies the ratios with which reactants react and products form
Understanding chemical changes requires recognizing that they can be represented by molecular, ionic, or net ionic equations These equations illustrate the process by which substances undergo chemical reactions, emphasizing the conservation of atoms, as they must contain equal numbers of each element on both sides of the equation to accurately depict the transformation.
A balanced chemical equation is essential for accurately representing chemical reactions at any level of chemistry It must be capable of being translated into a symbolic depiction at the particulate level, where much of the reasoning and understanding of chemical processes take place This balance ensures that the law of conservation of mass is maintained and facilitates deeper insights into chemical behavior and reactions.
As a result of this lesson, students should be able to:
• connect the number of particles, moles, mass, and volume of substances to one another, both qualitatively and quantitatively [LO 1.4, see SP 7.1]
• translate among macroscopic observations of change, chemical equations, and particle views [LO 3.1, see SP 1.5, 7.1]
Lesson 1: Representing Chemical Equations and Stoichiometry
This activity will be most effective if students are familiar with:
• the Law of Conservation of Matter
• the use of formulas to represent molecules and compounds
To strengthen understanding of chemical reactions, students should practice drawing reactants and accurately counting the number of each atom type in both compounds and molecules After sketching the products, students need to compare the atom counts in the reactants and products to observe how atoms are conserved during the reaction This approach enhances comprehension of chemical equations, atom conservation, and the process of balancing chemical reactions.
There have been many research studies focused on identifying student misconceptions and their difficulty understanding concepts related to stoichiometry Some of these include:
• Equating the mole ratio of molecules with the mass ratio of molecules in a reaction (Schmidt 1990)
• Understanding the role of the coefficient in a chemical-reaction equation and frequently including it in determining the molar mass of a substance (BouJaoude and Barakat 2000)
• Conserving atoms but not conserving molecules in a chemical reaction
• Understanding the concept of “limiting reagent” when one of the substances is added in excess (Huddle and Pillay 1996)
• Understanding the mole concept (Lazonby et al 1982)
A guided-inquiry approach to teaching stoichiometry effectively addresses common student difficulties by using robust models and scaffolded questions that promote active engagement Encouraging students to reflect on the relationships involved, rather than solely memorizing algorithms, enhances their conceptual understanding of both the qualitative and quantitative aspects of chemical reactions This method fosters deeper comprehension and helps students develop both conceptual clarity and problem-solving skills in chemistry.
This lesson aims to enhance your ability to effectively implement guided-inquiry activities in your teaching You will learn to create detailed plans for integrating guided inquiry into your course curriculum and identify strategies to facilitate engaging classroom activities Additionally, the included student activity is designed to help students explore, develop, and apply core concepts related to stoichiometry, fostering deeper understanding through active learning.
Lesson 1: Repr esent ing Chemical eq ua tions and s toic hiome tr y
A solid understanding of stoichiometry is essential, including the Law of Conservation of Mass, balancing chemical equations, and calculating moles based on the mass and chemical formulas Mastering mole ratios and molecular weight enables accurate chemical calculations Using simple shapes to represent atoms and molecules in particle-view diagrams helps visualize reactions, ensuring atoms are conserved during initial and final particle representations Translating between macroscopic observations, symbolic chemical equations, and particle-view diagrams is crucial for a comprehensive understanding of chemical reactions Being aware of common student misconceptions and typical errors in mathematical setup and calculations is important for mastering stoichiometry effectively.
XX Materials or Resources Needed
• LEGOs, chemistry model kits, or toothpicks and gummy bears (optional)
• Small (2’ × 3’) whiteboards, one for each group (optional)
Activity: Facilitating Guided Inquiry in the Classroom: Chemical-Reaction Equations
Effective facilitation of guided-inquiry activities and laboratories involves two essential phases: the first focusing on overall classroom structure and implementation, and the second on executing activities within the classroom Both phases are vital to ensure that guided-inquiry approaches successfully achieve meaningful learning outcomes.
XX Phase One: Getting Ready for Guided-Inquiry Learning
The first step in planning to use guided inquiry in your class is to ask yourself a series of questions:
To effectively engage students in guided-inquiry activities, it is essential to incorporate them regularly into your teaching routine These activities can be integrated daily, weekly, or at the start of each major topic to promote active learning and deepen understanding Consistent use of guided inquiry ensures students develop critical thinking skills and maintain sustained interest in the subject matter.
To maximize the effectiveness of guided-inquiry activities, it is recommended to structure learning teams with three to five students This team size fosters collaborative discourse, which has been shown to enhance students' conceptual understanding of science (Asterhan & Schwarz, 2007; Osborne, 2010; Zohar & Nemet, 2002).
Lesson 1: Representing Chemical Equations and Stoichiometry
Assessing group work requires effective strategies to evaluate collective outcomes, which can be more challenging than assessing individual performance To promote teamwork and skill development, accountability for group results is essential Effective assessment options include collecting a single completed activity per group, requiring groups to submit a recorder’s report with answers to key concepts and reflections, or implementing peer evaluations where members assess each other's contributions These methods ensure fair evaluation while fostering collaboration skills.
School Process Oriented Guided-Inquiry Learning (POGIL) Initiative
Valence Shell Electron Pair Repulsion (VSEPR) Model
Thomas J Greenbowe Iowa State University
Marian L DeWane University of California–Irvine
The calculation of the acid's concentration is influenced by the balanced chemical equation, the volume of acid used, and the volume and concentration of the base required to reach the equivalence point Accurate stoichiometric ratios derived from the balanced equation ensure precise determination of the acid's concentration The volume of acid and base titrated during neutralization directly affect the calculation, as they are essential for applying the titration formula Additionally, knowing the concentration of the base and the volume needed to neutralize the acid allows for accurate computation of the acid's molarity, highlighting the importance of precise measurements in titration procedures.
• How does the particle drawing of an acid and a base affect the particle drawing of the resultant solution?
Strong acids react with strong bases to produce a salt and water through neutralization For example, when hydrochloric acid reacts with sodium hydroxide in a 1-to-1 molar ratio, the resulting solution differs from the original reactants Neutralization occurs at the equivalence point, where the initial moles of hydronium ions (H₃O⁺) from the acid equal the moles of hydroxide ions (OH⁻) from the base The balanced chemical equation indicates the mole ratio between acid and base, enabling precise titration calculations Acid-base titrations provide valuable opportunities for students to connect macroscopic observations, symbolic chemical equations, and their particulate representations, enhancing their understanding of the underlying chemical processes.
To differentiate instruction, some students might gain a better understanding by using a graphing approach, others may benefit from using molecular model kits
To enhance understanding of AP Chemistry, students should engage with the curriculum module complemented by picture diagrams and additional end-of-chapter problems Hands-on experience with acid-base titrations using different acids and bases in the laboratory reinforces theoretical concepts and improves practical skills Utilizing diverse learning methods benefits all students, enabling a deeper grasp of acid-base reactions through both visual aids and experimental practice.
XX Connections to the AP Chemistry Curriculum Framework
In big idea 1 of the curriculum framework, students are expected to design and interpret data from an experiment to determine the concentration of an analyte
In order to accomplish this, they need to have mastered background knowledge from these other sections of the curriculum framework:
Understanding atoms and molecules is fundamental, as they interact at the atomic level Balanced chemical equations are crucial because they illustrate the precise number of particles that react and are produced during a chemical reaction To accurately analyze these processes, it is essential to express the amount of a substance in terms of the number of particles or moles, providing a clear understanding of chemical interactions and ensuring proper stoichiometric calculations.
• Essential knowledge 1.E.1: Physical and chemical processes can be depicted symbolically; when this is done, the illustration must conserve all atoms of all types
Understanding the conservation of atoms is essential for accurately calculating the masses of substances involved in both physical and chemical processes Since chemical reactions produce new substances, the quantities of these products depend on the types and amounts of elements present in the reactants, as well as the efficiency of the transformation This principle allows us to predict reactant and product masses by considering atomic conservation, ensuring precise analysis of chemical reactions.
• Enduring understanding 3.A: Chemical changes are represented by a balanced chemical equation that identifies the ratios with which reactants react and products form
As a result of this lesson, students should be able to:
• design and/or interpret data from an experiment that uses titration to determine the concentration of an analyte in a solution [LO 1.20, see
• express the Law of Conservation of Mass quantitatively and qualitatively using symbolic representations and particulate drawings [LO 1.17, see
Understanding how to identify solutions as mixtures of strong acids and/or bases is essential for accurately calculating or estimating the pH and the concentrations of all chemical species present Proper analysis involves assessing the initial concentrations of the acids and bases, then determining the extent of their neutralization reactions to find the resulting pH This process enables precise characterization of the final solution's acidity or alkalinity, which is critical for various chemical applications and laboratory procedures Mastering these calculations supports better predictions of solution behavior and compliance with safety and experimental standards.
Understanding how to relate quantities such as measured masses, solution volumes, and gas volumes and pressures is essential for identifying stoichiometric relationships in chemical reactions This includes analyzing reactions that involve limiting reactants, where one reactant is completely consumed, and recognizing situations where the reaction has not yet gone to completion, affecting the proportions of reactants and products Mastering these concepts allows for accurate determination of reactant and product quantities, enabling precise calculation of reaction yields and efficiencies.
• apply conservation of atoms to the rearrangement of atoms in various processes [LO 1.18, see SP 1.4]
• translate among macroscopic observations of change, chemical equations, and particle views [LO 3.1, see SP 1.5, 7.1]
This activity will be most effective if students are familiar with:
• using stoichiometry (balancing chemical equations, calculating moles, and identifying limiting reagents)
• classifying acids and bases, naming common inorganic acids and identify strong and weak acids and bases
• acid-base titrations and acid-base indicators
Students seeking to understand acid-base reactions can benefit from engaging in a short online simulation, which allows them to add indicators, identify acids and bases, and observe their reactions firsthand This interactive tool enhances comprehension of acid-base chemistry concepts and provides a practical, visual learning experience Access the simulation at http://www.wisc-online.com/Objects/ to reinforce your understanding of acids and bases.
• Thinking a neutral solution is formed when any acid reacts with a base
• Thinking that increasing the number of hydrogen atoms within a molecule increases the acidity of the compound
• Assuming it takes less base to neutralize a weak acid than is required to neutralize a strong acid, given the two acids have the same initial concentration
To address common misconceptions about neutralization reactions, students should perform simple titrations involving different acids and measure the pH at the point of neutralization, followed by a discussion on the hydrolysis of the resulting salt Additionally, testing the pH of weak and strong acids and bases—while comparing the number of hydrogen atoms in Lewis structures to the amount needed for neutralization—can clarify these concepts Handout 2, Activity 1, offers an effective activity to enhance students’ conceptual understanding of neutralization reactions between acids and bases.
This lesson will enhance your ability to effectively implement guided-inquiry activities, enabling you to create engaging lesson plans You will learn to design and utilize guided inquiry strategies to teach acid-base neutralization reactions By the end of this course, you will be capable of applying these techniques to promote active student learning and understanding of chemical concepts.
Lesson 2: A cid-Base neutr ali za tion Reac tions
This handout identifies effective strategies to facilitate classroom activities focused on understanding acid-base neutralization reactions The included student activities are designed to guide students through exploring, developing, and applying key stoichiometry concepts, enhancing their comprehension of acid-base chemistry These targeted approaches help students actively engage with the material, improving their ability to analyze and solve problems related to acid-base neutralization processes.
A comprehensive understanding of stoichiometry, acid-base reactions, and titrations is essential for mastering college-level chemistry Key concepts include the role of acid-base indicators in determining pH endpoints, Lewis diagrams for visualizing acid and base structures, and the behavior of simple acids like carboxylic acids and bases such as ammonia Additionally, grasping acid-base equilibria systems, salt formation, and particulate drawings enhances comprehension of acid-base reactions in aqueous solutions These foundational topics are crucial for success in general chemistry courses and are commonly illustrated through detailed diagrams and explanations in college textbooks.
XX Materials or Resources Needed
• Computers and Internet access to the acid-base titration computer simulation (or the computer simulation, which can be downloaded prior to class)
Step 1 Have students write the Law of Conservation of Matter, and then ask them the following:
• If matter is neither created nor destroyed during a chemical reaction, what can you say about the atoms involved in a chemical reaction?
• How can you determine when all of the acid reacts with the base, at the atom level, given the following chemical reaction:
HClO 4 (aq) + NaOH(aq) → NaClO 4 (aq) + H 2 O(l)?
• Draw a diagram representing a small portion of the initial system with
10 HClO 4 (aq) units: How many NaOH(aq) units would be needed to react with all of the acid? Explain what you did and what it indicates
Distribute Handout 2 and instruct students to complete Activities 1 and 2, integrating hands-on learning with computer simulations Students will work in pairs to perform titrations, utilizing a variety of acids and bases with different amounts and concentrations Assigning specific acids and bases to pairs ensures that at least four acids and four bases are titrated, enabling students to explore multiple concentrations and their effects This interactive activity is designed to be completed in approximately 20 minutes, providing a practical understanding of titration concepts.
Step 3 Direct students to complete Activity 3 This activity will require students to think about mole ratios in acid-base reactions, as well as developing particulate representations of such reactions
Step 4 Direct students to complete Activities 4 and 5 Students will need to transfer the content and skills learned in the prior activities to new data and new lab situations
During Activity 2, circulate around the room to assess students’ understanding of acid-base stoichiometry as they work with partners Upon completion, students record their data on the board, including acid type, initial concentration, volume, moles of H₃O⁺, base concentration, volume, and moles of OH⁻ ions They then create aligned graphs and atomic-level diagrams from their collected data to identify patterns If students struggle with the concepts or calculations, pose guiding questions—such as emphasizing that the initial moles of hydronium ions should equal the moles of hydroxide ions needed for neutralization—to reinforce understanding of the target stoichiometry principles.
XX Reflection on Formative Assessment
Ensure students’ calculations, graphs, and diagrams align accurately with the data when teaching acid-base titrations If students struggle to grasp the core concepts or their work appears inconsistent, consider revisiting foundational topics such as balancing chemical equations, basic stoichiometry, and molarity calculations to strengthen their understanding.
Lesson 2: A cid-Base neutr ali za tion Reac tions
Lesson 3: Valence Shell Electron Pair
Laura Trout Lancaster Country Day School
• What factors determine the three-dimensional shape of molecules?
• How does the shape of a molecule, along with intermolecular forces, affect its macroscopic properties?