6 | FRQ (Long) | Practice Sessions | AP Chemistry

Advanced Placement
24 Apr 202312:05
EducationalLearning
32 Likes 10 Comments

TLDRIn this AP Daily practice session six, Kristen Cacciatore guides students through the process of tackling long free response questions, focusing on the element aluminum (Al). The session begins with writing the electron configuration for an aluminum atom, which has 13 electrons arranged as 1s^2, 2s^2, 2p^6, 3s^2, 3p^1. The video then explains why the radius of an Al atom is larger than that of an Al^3+ ion, using atomic structure principles. A lab scenario involving the reaction between solid aluminum and an aqueous solution of silver ions is discussed, with instructions on preparing a precise concentration of silver nitrate solution using a volumetric flask. A particle diagram is completed to represent the reaction's outcome, ensuring conservation of mass and considering the balanced chemical equation. The video also covers calculating the cell potential (E°) for the reaction using standard reduction potentials and determining the standard free energy change (ΔG°), which is negative when E° is positive, indicating a thermodynamically favorable reaction. Finally, it addresses the change in free energy (ΔG) when the reaction stops, which is zero at equilibrium. The session concludes with review tips and resources for further study.

Takeaways
  • 📚 Start with the basics: The video begins by discussing the importance of understanding long free response questions, which are a part of the AP exam.
  • 🔬 Atomic Structure: The ground-state electron configuration of an aluminum atom is explained, highlighting the atomic number and electron distribution.
  • 🚀 Ions vs Atoms: The video explains why the radius of an Al atom is larger than that of an Al 3+ ion, using principles of atomic structure.
  • 🧪 Lab Preparation: A detailed procedure for preparing a precise volume of an aqueous solution of silver nitrate is provided, emphasizing the use of a volumetric flask.
  • 🧬 Particle Diagram: The video instructs on completing a particle diagram to represent a chemical reaction, focusing on conservation of mass and balanced chemical equations.
  • ⚖️ Redox Reactions: It is shown how to determine the limiting reactant in a reaction between aluminum and silver ions, leading to the formation of solid silver and aqueous aluminum ions.
  • 🔋 Cell Potential: The concept of standard reduction potentials is introduced, and the video demonstrates how to calculate the cell potential for a given reaction.
  • ⚡️ Energy Change: The video explains the relationship between cell potential and the standard free energy change of a reaction, indicating that a positive cell potential implies a negative free energy change.
  • ⚖️ Equilibrium: The script clarifies that when a reaction stops progressing, it has reached equilibrium, where the change in free energy (delta G) is zero.
  • 📈 Review Tips: The presenter offers suggestions for further review, linking to specific topics and additional resources for AP exam preparation.
  • 📅 Additional Resources: The video mentions that more AP Daily practice sessions and exam reviews for previous years are available on the YouTube channel for comprehensive exam preparation.
Q & A

  • What is the atomic number of aluminum?

    -The atomic number of aluminum is 13, which means it has 13 electrons.

  • How is the complete ground-state electron configuration of an aluminum atom written?

    -The complete ground-state electron configuration of an aluminum atom is written as 1s^2, 2s^2, 2p^6, 3s^2, 3p^1.

  • Why is the radius of the Al atom larger than the radius of the Al^3+ ion?

    -The radius of the Al atom is larger than that of the Al^3+ ion because when Al loses its three valence electrons to become Al^3+, its outermost electron shell becomes closer to the nucleus, resulting in a smaller size.

  • What is the correct equipment to prepare a precise 200.0 milliliters of an aqueous solution?

    -The correct equipment to prepare a precise 200.0 milliliters of an aqueous solution is a volumetric flask with a volume of exactly 200.0 milliliters.

  • What is the limiting reactant in the reaction between aluminum and silver ions?

    -The limiting reactant in the reaction between aluminum and silver ions is silver ions (Ag+), as there are only 8 silver ions available to react with aluminum atoms.

  • How many silver ions will react with aluminum in the given reaction?

    -Six silver ions (Ag+) will react with aluminum in the given reaction, as the largest multiple of 3 in 8 is 6, and the reaction ratio is 3 Ag+ to 1 Al.

  • What is the cell potential (E0) for the reaction between aluminum and silver ions?

    -The cell potential (E0) for the reaction between aluminum and silver ions is 2.46 volts, calculated by reversing the aluminum reduction half-reaction and adding the standard reduction potential of silver (0.8 volts) to the oxidation potential of aluminum (1.66 volts).

  • Is the standard free energy change (ΔG0) for the reaction positive, negative, or zero?

    -The standard free energy change (ΔG0) for the reaction is negative, as indicated by the positive cell potential (E0).

  • When the reaction stops progressing, what is the change in free energy (ΔG)?

    -When the reaction stops progressing, the change in free energy (ΔG) is zero, indicating that the reaction has reached equilibrium.

  • What is the significance of the cell potential (E0) being positive in the context of the reaction?

    -A positive cell potential (E0) indicates that the reaction is thermodynamically favorable, meaning it can proceed spontaneously under standard conditions.

  • What is the relationship between the cell potential (E0) and the standard free energy change (ΔG0)?

    -The relationship between the cell potential (E0) and the standard free energy change (ΔG0) is given by the equation ΔG0 = -nFE0, where n is the number of moles of electrons transferred and F is Faraday's constant. A positive E0 results in a negative ΔG0.

  • How can one enhance their understanding of the concepts discussed in the video script?

    -One can enhance their understanding by reviewing the suggested topics such as 1.5 and 1.7 for atomic structure, 4.5 for stoichiometry, 4.3 for particle representations, 9.8 for cell potential and free energy, and 9.9 for cell potential under non-standard conditions.

Outlines
00:00
📚 AP Daily Practice Session 6: Long Free Response Questions

Kristen Cacciatore introduces the sixth AP Daily practice session, focusing on long free response questions which are a key component of the AP exam. She provides a link to download a PDF of the questions for independent practice. The session begins with a question about the electron configuration of an aluminum atom, which is explained using the periodic table and atomic number. The session continues with a discussion on atomic structure, specifically why the radius of an aluminum atom is larger than that of an Al 3+ ion. The explanation involves the electron configuration and the valence shell. Subsequently, the script outlines a lab procedure for preparing a silver nitrate solution with a specific concentration, emphasizing the precision required and the use of a volumetric flask. The steps include partially filling the flask with distilled water, dissolving a measured solid, and adding water up to the calibration mark for an exact volume.

05:01
🧪 Completing Particle Diagrams and Understanding Redox Reactions

The video script continues with instructions to complete a particle diagram representing a reaction involving aluminum and silver ions. It emphasizes the need to maintain the conservation of mass and to consider the balanced chemical equation. The ratio of reactants is analyzed to determine the limiting reactant, which in this case is Ag+. The resulting products and remaining reactants are depicted in the diagram. Following this, the script discusses the use of standard reduction potentials to calculate the cell potential for the reaction. The aluminum reduction is reversed to form an oxidation half-reaction, and the potentials are summed to find the cell potential. The script concludes with a question about the standard free energy change of the reaction, explaining that a positive cell potential indicates a thermodynamically favorable reaction with a negative standard free energy change.

10:02
🔋 Cell Potential and Equilibrium in Redox Reactions

The final paragraph of the script addresses what happens when a reaction stops progressing. It clarifies that when a reaction reaches equilibrium, the cell potential (e) and the change in free energy (delta G) are both zero. This indicates that there is no longer a driving force for the reaction to proceed. The script then offers advice for exam review, suggesting specific topics to review based on the content covered in the session. It also directs viewers to additional AP Daily practice sessions and exam review material available on their YouTube channel. The session concludes with well wishes for the viewers' upcoming exams.

Mindmap
Keywords
💡Aluminum
Aluminum, denoted as Al, is a chemical element with an atomic number of 13. In the video, it is used as a central example for discussing various chemical concepts such as electron configuration and reactions. The video explains how to write the complete ground-state electron configuration for an aluminum atom, which is '1s^2 2s^2 2p^6 3s^2 3p^1', and also discusses the reaction of aluminum with silver ions.
💡Electron Configuration
Electron configuration refers to the arrangement of electrons around the nucleus of an atom. It is crucial in understanding the chemical properties of elements. In the video, the electron configuration of aluminum is used to explain why the radius of an aluminum atom is larger than that of an Al^3+ ion, due to the loss of valence electrons in the latter.
💡Valence Electrons
Valence electrons are the outermost electrons in an atom that are involved in chemical bonding. The video uses the concept of valence electrons to explain the difference in size between an aluminum atom and an Al^3+ ion, highlighting that the loss of valence electrons in the ion brings the remaining electrons closer to the nucleus, thus reducing the size.
💡Silver Nitrate
Silver nitrate is a chemical compound often used in laboratories. In the video, a student plans to combine solid aluminum with an aqueous solution of silver ions, which involves determining the mass of solid silver nitrate needed to prepare a solution with a specific concentration. This is part of the lab procedure discussed in the video.
💡Stoichiometry
Stoichiometry is the calculation involving the quantities of reactants and products in a chemical reaction. The video outlines the steps necessary to prepare a precise volume of an aqueous solution of silver nitrate, which is an application of stoichiometric principles. The procedure involves using a volumetric flask to ensure the exact volume and concentration of the solution.
💡Volumetric Flask
A volumetric flask is a piece of laboratory glassware used to prepare solutions of precise volume and concentration. In the video, it is used to demonstrate how to prepare a 200.0 milliliters solution of silver nitrate, highlighting its importance in achieving precise measurements in chemical procedures.
💡Particle Diagram
A particle diagram is a visual representation of the particles involved in a chemical reaction. The video uses a particle diagram to illustrate the incomplete reaction between aluminum and silver ions, and then completes the diagram to represent the system after the reaction has occurred, showing the conservation of mass and the products formed.
💡Standard Reduction Potential
Standard reduction potential is a measure of the tendency of a chemical species to be reduced, and it is used to calculate the cell potential of a redox reaction. In the video, the standard reduction potentials for silver and aluminum are given, and the video explains how to use these values to calculate the cell potential for the reaction between aluminum and silver ions.
💡Cell Potential
Cell potential, denoted as E°cell, is the difference in electrical potential between the two half-reactions in a redox reaction. The video calculates the cell potential for the reaction between aluminum and silver ions, showing that a positive cell potential indicates a thermodynamically favorable reaction.
💡Standard Free Energy Change
The standard free energy change (ΔG°) is a measure of the maximum reversible work that a thermodynamic system can perform at constant temperature and pressure. In the video, it is explained that a positive cell potential correlates with a negative standard free energy change, indicating that the reaction is thermodynamically favorable.
💡Equilibrium
Equilibrium in chemistry refers to a state in a reversible reaction where the forward and reverse reactions occur at the same rate, resulting in no net change in the system. The video discusses that when a reaction stops progressing, it has reached equilibrium, at which point the change in free energy (ΔG) is zero.
💡AP Daily Practice Sessions
AP Daily Practice Sessions are study aids designed to help students prepare for the AP (Advanced Placement) exams. The video is part of such a session, focusing on long free response questions related to chemistry. It provides a structured approach to understanding and solving complex chemistry problems, which is a key component of AP exam preparation.
Highlights

Introduction to AP Daily practice session six focusing on long free response questions

Link provided to download a PDF of the questions for self-study

Writing the complete ground-state electron configuration for an aluminum atom

Explanation of why the radius of an Al atom is larger than the Al 3+ ion based on atomic structure

Procedure for preparing a 200.0 mL aqueous solution of silver nitrate with precise steps

Use of a volumetric flask for precise volume and concentration of the solution

Completion of a particle diagram representing the system after a reaction occurs

Conservation of mass in the particle diagram with correct type and number of particles

Balancing the chemical equation and identifying the limiting reactant

Calculation of the cell potential (E°) for the reaction using standard reduction potentials

Determination of the standard free energy change (ΔG°) based on the cell potential

Explanation that a positive cell potential indicates a thermodynamically favorable reaction

Analysis of whether ΔG would be positive, negative, or zero when the reaction stops progressing

Understanding that ΔG equals zero at equilibrium when the reaction stops progressing

Suggestions for further review topics related to the session's content

Availability of additional AP Daily practice sessions and exam review resources on YouTube

Encouragement for exam preparation and well wishes for the viewers

Transcripts

Browse More Related Video

8 | FRQ (Long) | Practice Sessions | AP Chemistry

2021 Live Review 7 | AP Chemistry | Everything You Need to Know about Electrochemistry

2 | FRQ (Short) | Practice Sessions | AP Chemistry

Gibbs Free Energy - Entropy, Enthalpy & Equilibrium Constant K

4 | MCQ | Practice Sessions | AP Chemistry

Molecular, complete ionic, and net ionic equations | AP Chemistry | Khan Academy

Rate This

5.0 / 5 (0 votes)

Thanks for rating:

Related Tags
AluminumElectron ConfigurationAtomic StructureLab PreparationSilver NitrateRedox ReactionStandard ReductionCell PotentialFree EnergyEquilibriumAP Chemistry