AP Chemistry Flashcards: Reaction Rates

Study Reaction Rates in AP Chemistry with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.

AP Chemistry

Reaction Rates

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QUESTION
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Identify the rate-determining step in a reaction mechanism.

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ANSWER

The slowest step in the mechanism. Controls overall reaction rate.

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Flashcard 1: Identify the rate-determining step in a reaction mechanism.

Answer: The slowest step in the mechanism. Controls overall reaction rate.

Flashcard 2: How do you experimentally determine the rate law of a reaction?

Answer: Using the method of initial rates. Measure initial rates at different concentrations.

Flashcard 3: Define rate constant in the context of reaction rates.

Answer: The proportionality constant (k) in the rate law. Units depend on reaction order.

Flashcard 4: What is the effect of increasing concentration on reaction rate?

Answer: Increases the reaction rate. More reactant molecules available for collision.

Flashcard 5: What is the role of intermediates in a reaction mechanism?

Answer: Species that appear in the mechanism but not in the overall equation. Formed and consumed during reaction pathway.

Flashcard 6: What is the typical unit for reaction rate?

Answer: Molarity per second (M/s). Change in concentration per unit time.

Flashcard 7: What is the half-life formula for a first-order reaction?

Answer: t1/2=0.693kt_{1/2} = \frac{0.693}{k}. Time for concentration to drop to half initial value.

Flashcard 8: Which factors influence the activation energy of a reaction?

Answer: Nature of reactants and presence of a catalyst. Intrinsic properties determine energy barrier height.

Flashcard 9: What affects the frequency factor (A) in the Arrhenius equation?

Answer: Orientation and frequency of collisions. Pre-exponential factor in Arrhenius equation.

Flashcard 10: What does the term 'molecularity' refer to?

Answer: The number of molecules involved in an elementary step. Can be 1, 2, or 3 for elementary reactions.

Flashcard 11: What is the relationship between temperature and the rate constant?

Answer: Rate constant increases with temperature. Exponential relationship from Arrhenius equation.

Flashcard 12: State the Arrhenius equation.

Answer: k=AeEa/RTk = Ae^{-E_a/RT}. Relates rate constant to temperature and activation energy.

Flashcard 13: What is the effect of a catalyst on the rate constant?

Answer: Increases the rate constant. Provides lower activation energy pathway.

Flashcard 14: Identify the rate-determining step in a reaction mechanism.

Answer: The slowest step in the mechanism. Controls overall reaction rate.

Flashcard 15: Identify the rate-determining step in a reaction mechanism.

Answer: The slowest step in the mechanism. Controls overall reaction rate.

Flashcard 16: What is the relationship between temperature and the rate constant?

Answer: Rate constant increases with temperature. Exponential relationship from Arrhenius equation.

Flashcard 17: How does a catalyst affect the activation energy of a reaction?

Answer: Lowers the activation energy. Provides alternative pathway with lower energy barrier.

Flashcard 18: What is the integrated rate law for a first-order reaction?

Answer: [A] = [A]_0 e^{-kt}. Shows exponential decay of concentration.

Flashcard 19: How does surface area affect the rate of a heterogeneous reaction?

Answer: Increasing surface area increases the rate. More contact area means more collision sites.

Flashcard 20: What is the effect of temperature on the activation energy?

Answer: No effect; activation energy is constant. Activation energy is an intrinsic property.

Flashcard 21: What does the term 'reaction mechanism' refer to?

Answer: The step-by-step sequence of elementary reactions. Shows how overall reaction occurs at molecular level.

Flashcard 22: What is the relationship between temperature and the rate constant?

Answer: Rate constant increases with temperature. Exponential relationship from Arrhenius equation.

Flashcard 23: What is the effect of temperature on the activation energy?

Answer: No effect; activation energy is constant. Activation energy is an intrinsic property.

Flashcard 24: How do you experimentally determine the rate law of a reaction?

Answer: Using the method of initial rates. Measure initial rates at different concentrations.

Flashcard 25: What is the physical significance of the rate constant (k)?

Answer: Indicates speed of reaction at a given temperature. Larger k means faster reaction at same conditions.

Flashcard 26: What is the collision theory of reaction rates?

Answer: Reactions occur when particles collide with sufficient energy. Effective collisions have proper orientation and energy.

Flashcard 27: How do you experimentally determine the rate law of a reaction?

Answer: Using the method of initial rates. Measure initial rates at different concentrations.

Flashcard 28: How can the order of a reaction be determined experimentally?

Answer: By measuring how rate changes with concentration. Compare rates at different concentrations.

Flashcard 29: Which factor does not affect the rate constant?

Answer: Concentration of reactants. Rate constant only depends on temperature and catalyst.

Flashcard 30: What is the typical effect of a catalyst on reaction equilibrium?

Answer: No effect on equilibrium position. Speeds both forward and reverse reactions equally.

Flashcard 31: What is the effect of pressure on the rate of a gaseous reaction?

Answer: Increasing pressure increases the rate. Higher pressure increases concentration of gases.

Flashcard 32: What is the unit of the rate constant for a zero-order reaction?

Answer: M/s. Rate is independent of concentration.

Flashcard 33: Identify the units of the rate constant for a second-order reaction.

Answer: M^{-1} s^{-1}. Units are M1ns1M^{1-n}s^{-1} where n is overall order.

Flashcard 34: What is the effect of a catalyst on the rate constant?

Answer: Increases the rate constant. Provides lower activation energy pathway.

Flashcard 35: How do you determine the overall order of a reaction?

Answer: Sum the exponents of all reactants in the rate law. Add all concentration exponents in rate law.

Flashcard 36: Identify the unit of the rate constant for a third-order reaction.

Answer: M2s1M^{-2} s^{-1}. Pattern: M1ns1M^{1-n}s^{-1} where n=3.

Flashcard 37: Identify the rate-determining step in a reaction mechanism.

Answer: The slowest step in the mechanism. Controls overall reaction rate.

Flashcard 38: What is the typical effect of a catalyst on reaction equilibrium?

Answer: No effect on equilibrium position. Speeds both forward and reverse reactions equally.

Flashcard 39: Which graph is linear for a first-order reaction?

Answer: ln[A] vs. time. Integrated rate law form for first-order kinetics.

Flashcard 40: Identify the unit of the rate constant for a third-order reaction.

Answer: M^{-2} s^{-1}. Pattern: M1ns1M^{1-n}s^{-1} where n=3.

Flashcard 41: Identify the order of reaction if rate = k[A]^0[B]^1.

Answer: First order with respect to B. Zero order in A, first order in B.

Flashcard 42: What is the effect of temperature on the activation energy?

Answer: No effect; activation energy is constant. Activation energy is an intrinsic property.

Flashcard 43: What is the relationship between reaction rate and concentration for a zero-order reaction?

Answer: Rate is independent of concentration. Constant rate regardless of concentration changes.

Flashcard 44: What is the typical effect of a catalyst on reaction equilibrium?

Answer: No effect on equilibrium position. Speeds both forward and reverse reactions equally.

Flashcard 45: Define activation energy.

Answer: The minimum energy required to initiate a reaction. Energy barrier that must be overcome.

Flashcard 46: What affects the frequency factor (A) in the Arrhenius equation?

Answer: Orientation and frequency of collisions. Pre-exponential factor in Arrhenius equation.

Flashcard 47: What is the formula for the rate law of a reaction?

Answer: Rate = k[A]^m[B]^n. Where m and n are orders determined experimentally.

Flashcard 48: What is the effect of pressure on the rate of a gaseous reaction?

Answer: Increasing pressure increases the rate. Higher pressure increases concentration of gases.

Flashcard 49: What is the effect of pressure on the rate of a gaseous reaction?

Answer: Increasing pressure increases the rate. Higher pressure increases concentration of gases.

Flashcard 50: What is the typical effect of a catalyst on reaction equilibrium?

Answer: No effect on equilibrium position. Speeds both forward and reverse reactions equally.

Flashcard 51: State the expression for the half-life of a zero-order reaction.

Answer: t1/2=[A]02kt_{1/2} = \frac{[A]_0}{2k}. Half-life depends on initial concentration.

Flashcard 52: Identify the unit of the rate constant for a third-order reaction.

Answer: M^{-2} s^{-1}. Pattern: M1ns1M^{1-n}s^{-1} where n=3.

Flashcard 53: Identify the order of reaction if rate = k[A]^2.

Answer: Second order with respect to A. Exponent of [A] is 2.

Flashcard 54: What effect does increasing temperature generally have on reaction rate?

Answer: Increases the reaction rate. Higher temperature means faster molecular motion.

Flashcard 55: What is the role of a catalyst in a chemical reaction?

Answer: Speeds up the reaction without being consumed. Lowers activation energy but remains unchanged.

Flashcard 56: What is the purpose of a rate law?

Answer: To express how the rate depends on concentrations. Mathematical relationship between rate and concentration.

Flashcard 57: What is the effect of pressure on the rate of a gaseous reaction?

Answer: Increasing pressure increases the rate. Higher pressure increases concentration of gases.

Flashcard 58: Identify the order of reaction if rate = k[A][B].

Answer: Second order overall. Sum of exponents: 1 + 1 = 2.

Flashcard 59: How do you experimentally determine the rate law of a reaction?

Answer: Using the method of initial rates. Measure initial rates at different concentrations.

Flashcard 60: What is the relationship between temperature and the rate constant?

Answer: Rate constant increases with temperature. Exponential relationship from Arrhenius equation.