AP Chemistry FRQ Room

Acid-Base Titration Conceptual Error in Endpoint Determination

In an acid-base titration experiment to determine the concentration of acetic acid, a student uses a

Analysis of Periodic Trends: Atomic Radius and Ionization Energy

A table of data for elements in a period shows variations in atomic radii and ionization energies. U

Analyzing Periodic Trends: Electronegativity and Bonding

A table of electronegativity values for several elements is provided: | Element | Electronegativity

Application of Coulomb's Law and the Bohr Model

Apply Coulomb's law and the Bohr model to analyze atomic interactions.

Aufbau Principle and Electron Configuration Anomalies

Some transition metals exhibit electron configurations that deviate from the expected order. Answer

Average Atomic Mass Calculation from Isotopic Data

An element has the following isotopic data as shown in the table. Using the data, answer the followi

Catalytic Reaction Rate Experiment with Temperature Control Error

A chemical kinetics experiment is carried out to study the effect of various catalysts on the rate o

Comparative Analysis of Molarity and Percent Composition

In a laboratory setting, two methods are used to determine the concentration of a solution: one usin

Coulomb's Law and Electron Removal Energy

This question requires the application of Coulomb's Law to quantify the electrostatic force between

Coulomb's Law and Ionization Energy

Coulomb's law describes the electrostatic force between charged particles using the equation \(F =

Coulomb's Law and Ionization Energy

Consider an atom in which an electron is located at a distance of $$1.0\times10^{-10}$$ m from the n

Coulomb's Law in Atomic Ionization

Coulomb's law governs the force of attraction between electrons and the nucleus. This force plays a

Determining Empirical and Molecular Formulas

Solve a multi-part problem determining the empirical and molecular formulas from percent composition

Determining the Empirical Formula of an Unknown Hydrocarbon Using Combustion Analysis

A sample of an unknown hydrocarbon is subjected to complete combustion, and you are provided with th

Effects of Shielding on Atomic Radius

In an atomic physics study, the researcher examines how inner electrons affect the size of the atom

Electron Configuration and Orbital Filling

This question assesses your understanding of quantum mechanical principles as applied to electron co

Electron Configuration and Periodic Trends

Sulfur (atomic number 16) has electrons that fill various orbitals according to the Aufbau Principle

Empirical and Molecular Formula Determination from Percent Composition Data

Determining the empirical and molecular formulas of a compound from its percent composition is a fun

Empirical vs. Molecular Formulas of Organic Compounds

An organic compound is analyzed and determined to have the following percent composition: 80.0% C, 6

Interpreting Isotopic Mass Spectrum of Selenium

The following graph displays the mass spectrum of selenium, with peaks corresponding to its naturall

Mole-to-Particle Conversions and Stoichiometry

Convert between moles, number of particles, and mass, and analyze the impact of measurement uncertai

Moles and Avogadro's Number Applications

This question assesses your ability to use the mole concept in determining the number of particles a

Percent Composition of Calcium Nitrate

You will calculate the percent composition by mass for the compound calcium nitrate, Ca(NO₃)₂.

The Pauli Exclusion Principle and Hund's Rule

Understanding electron configuration requires an application of both the Pauli Exclusion Principle a

Titration and Molarity Determination with Indicator Misuse

In an experiment to determine the molarity of a hydrochloric acid solution, a student performs a tit

Transition Metals: Variable Oxidation States

A set of compounds formed by a transition metal (Element M) is summarized in the following table: |

Advanced Lewis Dot Structures and Geometry of Phosphorus Pentachloride

Phosphorus pentachloride (PCl5) involves interesting bonding features including resonance and an exp

Calculation of Lattice Energy Using Coulomb's Law

Use Coulomb's Law to calculate lattice energy for ionic compounds and analyze the effects of ionic c

Catalysis in Covalent Bond Formation Kinetics

A student investigates the role of a catalyst in a covalent bond-forming reaction by conducting para

Comparative Analysis of Alloy Types: Substitutional vs Interstitial

Different alloy types result from varying combinations of metals. Analyze the formation and properti

Comparative Analysis of Covalent and Ionic Bonding in Everyday Materials

This question asks you to compare the properties of substances with covalent and ionic bonds and to

Constructing Lewis Dot Structures with Incomplete Octets

Draw the Lewis dot structure for boron trifluoride (BF3) and explain its deviation from the octet ru

Covalent Bonding and Internuclear Distance Analysis

Analyze how the internuclear distance affects the potential energy in covalent bonds using a potenti

Designing an Experiment on Ion Mobility in Solutions

Design an experiment to investigate the factors influencing the mobility of ions in an aqueous solut

Electrostatic Attraction in Ionic Lattice Structures

A chemist is investigating the role of ionic charges and radii in lattice energy. Using the table pr

FRQ 8: Bond Strength and Internuclear Distance

A graph displaying potential energy versus internuclear distance for a diatomic molecule is provided

FRQ 18: Predicting Molecular Geometry from Hybridization

A table provides information on the hybridization and observed molecular geometries of several molec

FRQ10: Experimental Design – Ionic Bond Energy and Melting Points

A group of students is designing an experiment to explore the relationship between ionic bond energy

Interpreting Metallic Bonding Representations

Metallic bonding is characterized by a lattice of positive ions immersed in a 'sea of electrons'. An

Investigating Bond Energy and Reaction Kinetics in Ionic Compounds

This question examines the relationship between ionic bond energy and reaction kinetics, using disso

Investigating Metallic Alloys: Interstitial vs Substitutional

This question examines your understanding of the differences between interstitial and substitutional

Metallic Bonding and Alloy Conductivity Analysis

This question examines the role of metallic bonding in determining the conductive properties and mec

Molecular Geometry and VSEPR Analysis

A recent study challenges the predictive power of VSEPR theory by using examples of molecules with d

Molecular Geometry Determination and VSEPR Theory

A chemist is examining a molecule with the general formula $$AX_4E_1$$, where A is the central atom,

Molecular Modeling and Lone Pair Spatial Considerations

A student builds physical molecular models of water ($$H_2O$$) and ammonia ($$NH_3$$) to study the e

Multiple Bond Strength and Reactivity

A researcher examines how the number of bonds between atoms influences both the bond strength and th

Phase Transitions and Conductivity of Ionic Compounds

A physical chemist is examining how the electrical conductivity of an ionic compound changes as it t

Resonance and Bond Order Calculation

This question focuses on the effect of resonance on bond characteristics, particularly bond order, a

Resonance Stabilization and Formal Charge Distribution in $$NO_3^{-}$$

A researcher examines the nitrate ion $$NO_3^{-}$$ to understand how resonance stabilization affects

Resonance Structure Misinterpretation in Lewis Dot Structures

A student is assigned to draw the Lewis dot structures for the carbonate ion ($$CO_3^{2-}$$) and the

Solubility and Conductivity Comparison Misinterpretation

A student compares the electrical conductivity of aqueous solutions of sodium chloride (an ionic com

Understanding Conduction Mechanisms in Different Bonding Types

Electrical conductivity varies widely among compounds due to differences in bonding and structure. E

Vibrational Spectroscopy and Bond Force Constant Calculation

Vibrational spectroscopy can provide insight into bond strength. Using a diatomic molecule as a mode

Beer’s Law and Concentration Measurement

A solution containing a colored compound is analyzed using a spectrophotometer. The measured absorba

Chromatographic Separation of Mixtures

Apply principles of paper chromatography to separate a dye mixture and interpret the data to determi

Column Chromatography Process Analysis

Analyze the process of column chromatography for separating mixtures and discuss ways to improve its

Comparative Analysis of Boiling Points and Intermolecular Forces

Use the provided data to analyze the relationship between molecular structure, intermolecular force

Dalton's Law in Gas Mixtures

In an experiment, a container holds a mixture of gases at a total pressure of 3.0 atm. The moles of

Density and Molar Mass Calculation of Gases

Analyze the relationship between density and molar mass in gases and use this relationship to identi

Density Calculation of Gases

A chemist wishes to determine the molar mass of an unknown gas from its measured density. Answer the

Designing a Column Chromatography Experiment

Column chromatography utilizes polarity differences to separate mixtures. Develop an experimental de

Dipole–Dipole Interactions in Organic Molecules

Examine how dipole–dipole interactions influence physical properties such as boiling points in organ

Distillation and Boiling Point Separation

Distillation separates liquid mixtures based on boiling point differences. Analyze the distillation

Effusion and Gas Law Calculations

Investigate the relationship between molecular mass and the rate of effusion of gases, and apply gas

Effusion and Molar Mass Calculation

A researcher determines the molar mass of an unknown gas by measuring its rate of effusion compared

Effusion Rate Analysis Using Graham’s Law

Effusion is the process by which gas molecules escape through a small opening. Graham's Law, express

Effusion Rate Experiment: Investigating Gas Separation

A student proposes an experiment to measure the effusion rate of two different gases through a very

Gas-Phase Reaction Kinetics: Temperature and Pressure Dependence

A researcher aims to study the kinetics of a gas-phase reaction by investigating the influence of te

Molecular Polarity Analysis

A chemist is investigating how molecular geometry influences molecular polarity using the molecules

Non-Ideal Gas Behavior

Discuss the limitations of the ideal gas law by identifying the conditions that lead to deviations f

Phase Changes and Bond Energy Considerations

A chemist is investigating the energy requirements for phase transitions in substances characterized

Reaction Kinetics and Intermolecular Forces

A researcher investigates a multi‐step reaction in which intermolecular forces significantly affect

Reaction Mechanism and Solvent Effects

The polarity of a solvent can significantly influence the mechanism and rate of substitution reactio

Solvent Polarity and Solubility Relationship

The principle 'like dissolves like' suggests that polar solvents are more effective at dissolving po

Spectroscopy and Beer’s Law Analysis

A researcher uses UV-Vis spectroscopy to determine the concentration of a colored compound in soluti

Vapor Pressure and Phase Change Analysis

Discuss the relationship between intermolecular forces and vapor pressure, and how these factors con

Chemical Equilibrium in Acid-Base Reactions

A researcher examines the equilibrium established in the acid-base reaction of acetic acid with wate

Combustion Analysis of a Hydrocarbon

A hydrocarbon of unknown formula is completely combusted, producing 33.0 g of CO₂ and 14.0 g of H₂O.

Combustion Analysis of a Hydrocarbon

A 1.00 g sample of a hydrocarbon with formula $$C_xH_y$$ is completely combusted. The combustion pro

Combustion Analysis of a Hydrocarbon

Combustion analysis can be used to determine the empirical formula of an unknown hydrocarbon. Design

Comparing Reaction Yields: Theoretical vs. Actual

In a reaction, the theoretical yield of a product is calculated to be $$12.0$$ g, but the experiment

Decomposition Reaction Analysis

A decomposition reaction following the form AB → A + B was studied at various temperatures. The foll

Determination of Oxidation States in Complex Compounds

For the compounds \(H_2O\), \(H_2O_2\), \(FeCl_3\), and \(KMnO_4\), assign the oxidation state for e

Electrolysis and Faraday’s Laws

During the electrolysis of aqueous copper(II) sulfate using copper electrodes, a constant current of

Experimental Design: Effect of Concentration on Redox Kinetics

A research laboratory is investigating how the concentration of reactants affects the rate of a redo

FRQ 3: Gravimetric Analysis of an Unknown Alkali Hydroxide

A 4.33 g sample of an unknown alkali hydroxide is completely dissolved and reacted with copper(II) n

FRQ 5: Oxidation States and Redox Reaction Balancing

Consider the redox reaction $$Fe + 2\,HCl \rightarrow FeCl_2 + H_2$$. Analyze the oxidation states o

FRQ 8: Limiting Reactant and Yield in a Synthesis Reaction

Consider the synthesis reaction $$2\,A + 3\,B \rightarrow C$$. A student mixes 5.00 g of A (molar ma

FRQ 17: Combustion Analysis and Environmental Impact

A study compares the combustion of a hydrocarbon under complete and incomplete conditions. Complete

FRQ 18: Electrochemical Cell and Electrode Potentials

A galvanic cell is constructed using a $$Zn/Zn^{2+}$$ half-cell and a $$Cu/Cu^{2+}$$ half-cell, with

Gravimetric Analysis of an Unknown Salt

An unknown salt that contains chloride ions is analyzed by precipitating AgCl from a 1.00 g sample u

Interpreting Oxidation States in Redox Reactions

Examine the following redox reaction: $$Fe + 2*HCl → FeCl_{2} + H_{2}$$.

Investigation of Reaction Mechanisms

A researcher is studying the mechanism of a reaction that produces an intermediate species during th

Kinetics Data Analysis and Error Evaluation

A student investigates the decomposition of compound X and records the following data: | Time (s) |

Large Scale Combustion Reaction Analysis

Butane ($$C_4H_{10}$$) is combusted in an industrial furnace according to the balanced reaction: $$2

Oxidation State Determination and Redox Reaction Analysis

A researcher is investigating oxidation state changes in a redox reaction. Consider the reaction: $$

Precipitation Reaction and Gravimetric Analysis

Gravimetric analysis is a reliable method for quantitative determination through precipitation. Desi

Precipitation Reaction and Solubility Rules

A solution of 0.100 M $$Na_2SO_4$$ is mixed with 0.100 M $$BaCl_2$$. The reaction that occurs is the

Reaction Kinetics of a Decomposition Reaction

The decomposition of compound A follows first order kinetics. The following table provides the conce

Redox Titration Analysis Using KMnO4

In a redox titration, potassium permanganate ($$KMnO_{4}$$) is used to determine the concentration o

Synthesis of an Ester via Acid-Catalyzed Reaction

A student synthesizes an ester by reacting an alcohol with a carboxylic acid using sulfuric acid as

Synthesis Reaction for a Complex Salt

A laboratory procedure is designed to synthesize a complex salt by reacting a metal oxide with a car

Synthesis Reaction: Production of Compound AB

A chemist is designing a synthesis reaction to produce compound $$AB$$ by combining pure element $$A

Thermochemical Considerations in Synthesis and Decomposition

A synthesis reaction releases $$\Delta H = -200\,kJ$$ while a decomposition reaction absorbs $$\Delt

Thermochemistry of Benzene Combustion

Benzene ($$C_6H_6$$) combusts with oxygen to produce carbon dioxide and water. Using the standard en

Thermodynamics: Enthalpy Change in a Reaction

Consider the synthesis reaction: $$N_2 (g) + 3*H_2 (g) \rightarrow 2*NH_3 (g)$$. A calorimetry exper

Writing and Balancing Redox Reactions

Consider the unbalanced redox reaction: $$Fe + HCl \rightarrow FeCl_2 + H_2$$.

Advanced Data Analysis for Second-Order Reactions

An experiment investigating a second-order reaction provides a plot of $$1/[A]$$ versus time that sh

Analyzing Rate Law from Concentration Doubling Experiments

A reaction follows the rate law $$\text{Rate} = k [X]^m [Y]^n$$. The following experimental data wer

Arrhenius Plot Analysis

Arrhenius plots are a common graphical tool used to determine activation energy. Answer the followin

Arrhenius Plot and Activation Energy Determination

The Arrhenius equation relates the rate constant $$k$$ to temperature $$T$$ and activation energy $$

Collision Theory and Reaction Rates

For a gas‐phase reaction, collision theory postulates that the rate of reaction is proportional to t

Competing Steps in Reaction Mechanism

In the reaction $$A + B \to C$$, two competing pathways are proposed: Pathway 1 (fast): Step 1:

Complex Effects of Reactant Concentration on Reaction Mechanisms

A reaction is studied by varying the concentrations of reactants A and B. The following data were ob

Correlation between Reaction Mechanism Steps and Experimental Rate Law

A reaction is proposed to proceed by two different mechanisms. One mechanism is a single-step, bimol

Deriving Net Rate Law from Multi-Step Reaction Mechanism

Consider the following two-step reaction mechanism: I. $$M \rightarrow N$$ (fast equilibrium) II.

Designing a Kinetic Experiment: Second-Order Reactions

A chemist is designing an experiment to determine the kinetic parameters of a new reaction suspected

Determination of Reaction Order from Time-Concentration Data

A researcher investigates the decomposition of reactant A at constant temperature. The following dat

Determining Half-Life for a First-Order Reaction

A first-order reaction is monitored and the concentration of reactant A is measured over time. The e

Determining Reaction Mechanism from Kinetic Data

Experimental studies of the reaction 2A + B → C yield a rate law of the form Rate = k [A]^2[B]. a.

Identification of the Rate-Determining Step

A multi-step reaction has been proposed with the following mechanism: Step 1 (fast): $$A + B \to I$

Interpreting Reaction Energy Profiles

A reaction energy profile diagram is provided below. The diagram shows the energy of the reactants a

Investigating Reaction Mechanisms by Detecting Intermediates

In a reaction suspected to involve a short-lived intermediate, a researcher uses a radical scavenger

Investigation of an Intermediate in a Multi-Step Reaction

A reaction proceeds through the following mechanism: Step I: $$A \rightarrow X$$ (fast) Step II: $

Reaction Energy Profile and Catalysis

Examine the reaction energy profile provided and answer the following parts related to activation en

Reversible Reaction Kinetics: Neglecting the Reverse Reaction

An experiment was designed to study the kinetics of the reaction $$A \rightarrow B$$. The initial ra

Surface Area Effects in Heterogeneous Catalysis

A series of experiments were performed to study the effect of catalyst surface area on the rate of a

Surface Area Effects in Heterogeneous Catalysis: Error in Catalyst Characterization

In an experiment to study the effect of catalyst surface area on reaction rates, the researcher grou

Advanced Calorimetry: Non-Ideal Conditions

During an experiment in a poorly insulated calorimeter, the temperature vs. time data deviates from

Analyzing a Two-step Reaction: Applying Hess’s Law

A researcher asserts that a complex reaction can be decomposed into two steps, with the overall enth

Bond Energy Calculation and Reaction Enthalpy

Consider the reaction: $$2*H_2(g)+O_2(g)\rightarrow 2*H_2O(l)$$. Use the bond energies provided in t

Bond Energy Calculations in Reaction Thermochemistry

Using bond energy concepts, analyze the reaction $$N_2 + 3 H_2 \rightarrow 2 NH_3$$ by calculating t

Calculating Reaction Enthalpy using Bond Energies

For the combustion reaction: $$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$$, bond energy calculations can

Calorimetry Experiment Analysis

A student uses a calorimeter to measure the heat released during an exothermic reaction in water. Th

Comprehensive Analysis of a Multi-step Reaction Mechanism

This FRQ requires a thorough analysis of a multi-step reaction mechanism, including the identificati

Designing a Calorimetry Experiment

A researcher aims to measure the heat of reaction using a calorimeter.

Determination of Enthalpy of Formation (ΔHf)

A student carries out a multistep synthesis experiment to determine the enthalpy of formation (ΔHf)

Determination of Enthalpy of Formation from Experimental Data

Experimental data has been collected to study the formation of compound X from its elements. The for

Determining Reaction Enthalpy using Bond Energies

For the synthesis reaction of ammonia: $$\text{N}_2 + 3\,\text{H}_2 \rightarrow 2\,\text{NH}_3$$ cal

Effect of Surface Area on Reaction Rate in Heterogeneous Systems

Surface area of a solid reactant can significantly influence the rate of a heterogeneous reaction. D

Energy Changes and Molecular Stability

A series of reactions show different enthalpy changes. Consider a reaction where compound A has \(\D

Energy Diagram Analysis of an Exothermic Reaction

An experiment produced an energy diagram for a chemical reaction where the energy level of the react

Enthalpy Change Calculation from Bond Energies

Consider the combustion reaction of ethane given by $$C_{2}H_{6} + \frac{7}{2}O_{2} \rightarrow 2CO_

Enthalpy of Formation Calculations

Calculate the enthalpy change for the combustion reaction of carbon (graphite) to form carbon dioxid

Enthalpy of Formation Using Hess's Law

Consider the reaction for the formation of methanol: $$C(s) + \frac{1}{2}O_2(g) + 2H_2(g) \rightarro

Error Analysis in Calorimetry

A student recorded temperature vs. time data in a calorimetry experiment, with each data point accom

Evaluating Experimental Design in Calorimetry

A research group designed an experiment to measure the enthalpy change of a neutralization reaction

Interpreting Energy Flow in Exothermic Reaction Systems

In a laboratory demonstration, a beaker containing a chemical reaction shows a noticeable increase i

Investigating Heat Transfer in Liquid Mixtures

A researcher performs an experiment by mixing 50.0 g of water at 80.0°C with 50.0 g of water at 20.0

Investigating Specific Heat in Natural Water Bodies

Water bodies such as lakes and oceans have high specific heat, which influences their temperature re

Light-Driven Photochemical Reactions and Thermodynamic Changes

Photochemical reactions absorb light energy, leading to unique thermodynamic changes. Explain the th

Phase Change Analysis Using a Temperature-Time Graph

A heating curve for a substance is provided, showing a plateau region during the phase change from s

Thermodynamic Analysis of Bond Formation and Breaking

A chemical reaction involves breaking bonds in the reactants and forming bonds in the products. If t

Thermodynamics of Vaporization

An experiment is performed to study the vaporization of water. During the boiling process in a seale

Acid Dissociation Equilibrium Analysis

Consider the dissociation of a weak acid, HA, in water given by: $$HA(aq) \rightleftharpoons H^+(aq)

Acid-Base Equilibria and Dissociation Constants

Consider the ionization of a weak acid HA: $$\ce{HA (aq) <=> H+ (aq) + A^- (aq)}$$, where the acid d

Analyzing Kp and Kc in Gas-Phase Equilibria

A researcher studies the gaseous reaction: $$2*X(g) + Y(g) ⇌ 3*Z(g)$$. Considering the relationship

Application of the Reaction Quotient (Q) Analysis

In a chemical system not initially at equilibrium, the reaction quotient (Q) can be used to predict

Calculating Equilibrium Constant from Experimental Data

Outline the process for determining the equilibrium constant (Kₑ𝚚) from experimental concentration

Calculating Q for a Complex Reaction

For the reaction $$2*A + B \leftrightarrow 3*C + D$$, use the following data to calculate the reacti

Combined Equilibrium Reactions and Keq Calculation

Consider the following two reversible reactions with their respective equilibrium constants: Reacti

Common Ion Effect in Solubility Equilibria

Consider the salt $$CaF_2$$, which dissolves according to the reaction: $$CaF_2 (s) \rightleftharpoo

Common Ion Effect on Complex Ion Formation

The formation of the iron(III) thiocyanate complex is represented by the equilibrium reaction: $$\te

Common Ion Effect on Solubility Product

An experiment studies the solubility of silver chloride (AgCl) in pure water and in a solution conta

Comparative Analysis of Salt Solubilities

Two salts, Salt A and Salt B, have solubility product constants $$K_{sp,A}$$ and $$K_{sp,B}$$, respe

Computational Equilibrium Constant Derivation

Given the following reactions and their equilibrium constants: Reaction A: $$D \rightleftharpoons E$

Decomposition of PCl5: Misinterpretation of Pressure Effects

In an experiment investigating the equilibrium of the reaction $$PCl_5 (g) \rightleftharpoons PCl_3

Designing a Reaction Vessel Experiment for Yield Optimization

An industrial chemical process involves a reversible reaction whose yield depends on pressure, tempe

Designing an Experiment on the Common Ion Effect in AgCl Solubility

Silver chloride (AgCl) is sparingly soluble in water. When a salt containing a common ion, such as N

Designing an Experiment to Determine Keq

You are tasked with designing a laboratory experiment to determine the equilibrium constant (Kc) for

Determining Equilibrium Concentrations from Reaction Data

Consider the equilibrium reaction: $$A + B \rightleftharpoons C$$ with initial concentrations $$[A

Determining Molar Solubility and the Impact of the Common Ion Effect in Calcium Fluoride

Analyze the solubility characteristics of calcium fluoride (CaF2) in pure water and in the presence

Dilution Effects on Aqueous Equilibrium

For the equilibrium reaction $$Fe^{3+}(aq) + SCN^{-}(aq) \leftrightarrow FeSCN^{2+}(aq)$$, answer th

Distinguishing Reaction Kinetics from Equilibrium: Error Analysis

A researcher studies the reaction $$A + B \rightleftharpoons C$$ by measuring initial reaction rates

Dynamic Equilibrium and Reaction Quotient Analysis

For the reaction: $$2M(g) \rightleftharpoons N(g) + 3O(g)$$, at a given moment, the concentrations a

Effect of Noble Gases on Equilibrium

Consider the gaseous equilibrium: $$A (g) + B (g) \rightleftharpoons C (g)$$. (a) Describe the effec

Equilibrium Concentration Calculations Using ICE Tables

Consider the reaction $$\text{N}_2 + 3*\text{H}_2 \leftrightharpoons 2*\text{NH}_3$$. Initially, 1.0

Equilibrium Shifts in Response to External Stressors

Consider the equilibrium reaction: $$A + B \rightleftharpoons C + D$$. External changes in concentra

Evaluating Experimental Errors in Equilibrium Constant Determination

An experiment is performed to determine the equilibrium constant $$K_{eq}$$ for the reaction: $$\ce{

Experimental Design: Determining Ksp of a Sparingly Soluble Salt

Design an experiment to determine the solubility product constant (Ksp) of a sparingly soluble salt

Graph Analysis of Equilibrium Attainment

A graph depicting the concentration of reactants and products over time for a reversible reaction is

Graphical Analysis of Equilibrium Shifts

A reaction in a closed system exhibits varying concentrations over time. Analyze the provided graph

Haber Process Equilibrium Analysis

Consider the Haber process given by $$N_2 + 3*H_2 \leftrightharpoons 2*NH_3$$. This reaction is reve

Haber Process Equilibrium Calculation

In the Haber process, $$N_2 + 3*H_2 \leftrightarrow 2*NH_3$$, a container initially contains $$[N_2]

Haber Process Equilibrium Measurement Error

In a controlled experiment investigating the equilibrium constant for the Haber process, a chemist f

Heterogeneous Equilibria and Gas Addition: Error in Conceptual Approach

In an experiment involving the equilibrium of calcium carbonate decomposition $$CaCO_3 (s) \rightlef

Influence of Catalyst Presence on Reaction Dynamics

In an experiment studying the reaction $$D + E \rightleftharpoons F$$, two identical reaction mixtur

Le Chatelier's Principle: Effect of Concentration Changes

Consider the aqueous equilibrium: $$\mathrm{Fe^{3+} + SCN^{-} \rightleftharpoons FeSCN^{2+}}$$. Answ

Manipulating Equilibrium Constants via Hess’s Law

Design an experiment in which you measure the equilibrium constants of two simpler reactions and the

Manipulating Equilibrium Constants via Reaction Combination

Given the two reactions: 1) $$A \leftrightarrow B$$ with equilibrium constant $$K_1$$, 2) $$B \leftr

Manipulating Keq Using Hess’s Law

Consider the following hypothetical reactions: Reaction 1: $$CO(g) + \frac{1}{2}O_2(g) \rightarrow

Manipulation of Equilibrium Expressions: Coefficient Changes and Reversals

For the reaction $$X (g) + 2*Y (g) \rightleftharpoons 3*Z (g)$$, analyze how modifications affect th

Multiple Equilibria in Aqueous Systems

In an aqueous solution, two equilibria occur simultaneously: (1) $$C(aq) + D(aq) \rightleftharpoons

Noble Gas Effects on Reaction Equilibrium

Consider the gaseous reaction $$A(g) + B(g) \leftrightharpoons C(g)$$. Answer the following parts re

Precipitation Reaction Analysis: Mixing of Solutions

A solution of 0.050 M Na$_2$SO$_4$ is mixed in equal volumes with a 0.10 M BaCl$_2$ solution. Barium

Predicting Shifts in Complex Ion Formation Equilibria

Consider the complex ion formation equilibrium: $$\ce{Cu^{2+} (aq) + 4NH3 (aq) <=> [Cu(NH3)_4]^{2+}

Pressure Effects on Gaseous Equilibrium in the Haber Process

For the synthesis of ammonia $$N_2 + 3*H_2 \leftrightarrow 2*NH_3$$, consider how pressure changes a

Quantitative Analysis of the Common Ion Effect on Solubility

A salt, $$AB_{2}$$, dissolves in water according to: $$AB_{2}(s) ⇌ A^{2+}(aq) + 2*B^{-}(aq)$$ with a

Quantitative Equilibrium Calculation in a Weak Acid System

A weak acid, HA, dissociates according to $$HA \leftrightarrow H^{+} + A^{-}$$. In a 1.0 L solution,

Reaction Quotient vs. Ksp in Precipitation Reactions

When solutions of barium chloride (BaCl2) and sodium sulfate (Na2SO4) are mixed, barium sulfate (BaS

Role of Catalysts in Chemical Equilibrium

Explain the impact of catalysts on reaction rates and the position of chemical equilibrium in revers

Solubility and Temperature Variation

Explore the effects of temperature on the solubility of salts and the corresponding solubility produ

Solubility Changes with Temperature: An Experimental Analysis

A series of experiments measured the solubility of a sparingly soluble salt at various temperatures.

Solubility Product and Precipitation: Calculation Challenge

Consider the dissolution of calcium fluoride: $$CaF_2(s) \leftrightharpoons Ca^{2+}(aq) + 2*F^{-}(aq

Solubility Product Constant (Ksp) Calculation

Define and utilize the solubility product constant (Ksp) to predict the solubility of a sparingly so

Solubility Product Constant Calculations

For the dissolution of calcium fluoride, represented by $$CaF_2(s) \leftrightarrow Ca^{2+}(aq) + 2*F

Temperature and Reaction Energetics in Exothermic vs. Endothermic Reactions

Two reactions are studied under identical conditions. Reaction 1 is exothermic with $$\Delta H = -80

Temperature and Solubility

The following table provides the solubility of a salt in water at different temperatures: | Tempera

Uncertainty and Error Analysis in Equilibrium Studies

An experiment was conducted to measure the equilibrium concentrations for the reaction: $$G + H \rig

Analysis of Polyprotic Acids

Phosphoric acid (H₃PO₄) is a polyprotic acid with dissociation constants $$K_{a1} = 7.1 \times 10^{-

Autoionization of Water and pH Limits

Derive the classical relationship for water autoionization and discuss why pH values might fall outs

Buffer Capacity Under Acid Addition: Misinterpretation of Buffer Limits

A student prepared a buffer solution from acetic acid and sodium acetate and then incrementally adde

Buffer pH Calculation

A buffer solution is prepared by mixing 0.20 M acetic acid (HC2H3O2) with 0.15 M sodium acetate (NaC

Buffer Response in a Weak Acid–Strong Base Titration

During the titration of a weak acid with a strong base, the solution exhibits a buffer region where

Buffer System Experiment Design

A chemistry student aims to prepare a buffer solution using acetic acid (HC2H3O2) and its conjugate

Common Ion Effect and Its Impact on Solubility

The solubility of sparingly soluble salts can be substantially affected by the common ion effect.

Common Ion Effect on Solubility of Magnesium Hydroxide

An experiment investigates the solubility of magnesium hydroxide, $$Mg(OH)_2$$, in solutions with va

Determining pKb from a Known pKa

A study of conjugate acid-base pairs involves using the relation $$pK_a + pK_b = 14$$. For acetic ac

Impact of pH on Solubility of Mg(OH)2

This FRQ investigates how solution pH affects the solubility of the sparingly soluble hydroxide salt

Indicator Chemistry in Acid-Base Titrations

Indicators are weak acids that change color during a titration because of a change in their ionizati

Indicator Transition Misinterpretation in Acid–Base Titration

During a titration of a weak acid with a strong base, a student chose phenolphthalein as the indicat

Polyprotic Acid Titration Analysis

Polyprotic acids like H₃PO₄ dissociate in multiple steps, each with its own acid dissociation consta

Polyprotic Buffer Misapplication in pH Control

For a biochemical assay, a researcher attempted to prepare a buffer solution using phosphoric acid (

Strong Acid pH and Dilution Effects

A solution of a strong acid has an initial hydrogen ion concentration of $$[H^+] = 1.0 \times 10^{-2

Comparative Analysis of Galvanic vs. Electrolytic Cells

Compare and contrast the working principles of galvanic and electrolytic cells, especially in the co

Comparative Analysis of Reaction Spontaneity from Provided Data

The following table presents thermodynamic data for three different reactions at 298 K.

Comparative Analysis of Redox Reactions

A researcher is provided with several redox half-reactions and their standard reduction potentials.

Comparing Galvanic and Electrolytic Cells

A table below compares key properties of galvanic (voltaic) cells and electrolytic cells. Analyze th

Comparison Between Galvanic and Electrolytic Cells

Discuss the differences between galvanic (voltaic) cells and electrolytic cells in terms of cell con

Effect of Non-Standard Conditions on Cell Voltage Using the Nernst Equation

Consider the reaction $$Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)$$. Using the Nernst equa

Energy Efficiency Analysis in Electrochemical Cells

Compare the calculated energy efficiency (using thermodynamic data) with the actual measured efficie

Entropy Change Calculation and Interpretation

Consider the reaction: $$A_{(l)} + 2B_{(s)} \rightarrow 3C_{(g)}$$. A table of standard entropy valu

Entropy Change in a Reaction

A student investigates the entropy change for the reaction $$2*A(g) + B(l) \rightarrow 3*C(g) + D(s)

Evaluating Electrolysis Efficiency

An electroplating experiment operating at a current of 5.00 A for 2 hours resulted in 10.0 g of meta

Explaining the Role of the Salt Bridge in Galvanic Cells

Examine the provided schematic diagram focusing on the salt bridge in a galvanic cell.

FRQ 11: Relating Equilibrium Constants to Cell Potentials

A certain redox reaction in a galvanic cell involves an exchange of \(n = 3\) electrons and has a st

FRQ 13: Calculating Deposited Mass in Electroplating

In an electroplating experiment, silver is deposited according to the reaction: $$Ag^+ + e^- \right

Gibbs Free Energy and Equilibrium Constant

Investigate the relationship between the standard Gibbs free energy change (ΔG°) and the equilibrium

Gibbs Free Energy Correction Under Non-Standard Conditions

A redox reaction is observed under non-standard conditions and its cell potential is lower than the

Investigating Temperature Effects on Free Energy

A researcher examines how temperature influences the free energy change of a redox reaction. A table

Investigating the Effect of Pressure on Reaction Entropy

Design an experiment to measure the impact of pressure on the entropy change of a gas-phase reaction

Linking Equilibrium Constant and Gibbs Free Energy

A chemist uses equilibrium measurements to analyze a reaction at 298 K. The researcher intends to us

Phase Equilibria and Gibbs Energy

Water undergoes phase changes that can be analyzed using Gibbs free energy. Consider the liquid-gas

Predicting Spontaneity in Redox Reactions

Given the following half-reactions and their standard reduction potentials: (a) $$\text{Fe}^{3+} + e

Quantitative Analysis of Electron Flow in Electrolysis

An electrolytic cell is operated at a current of $$5*A$$ for 600 seconds, and the plating reaction r

Reduction Potential and Overall Redox Reaction

Analyze the overall redox reaction using provided half-reactions and discuss the implications of ele

Reduction Potentials and Reaction Feasibility

A researcher analyzes two half-reactions with standard reduction potentials provided below. Using th

Standard Free Energy Change from Equilibrium Constant

A particular reaction at 298 K has an equilibrium constant $$K = 150$$. Determine the standard free

Temperature Dependence of Redox Potential

A researcher studies how changing the temperature affects the cell potential in a galvanic cell.

Understanding Charge Flow and Faraday’s Law in Electrolysis

In an electrolytic cell, charge flow is critical for the deposition of material on an electrode. A s