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Questions and Answers
What are the units for the rate of a reaction when concentration is measured in mol L–1 and time in seconds?
What are the units for the rate of a reaction when concentration is measured in mol L–1 and time in seconds?
- mol L–1
- atm s–1
- mol L–1s–1 (correct)
- L s–1
The average rate of a reaction does not depend on the change in concentration of the reactants or products.
The average rate of a reaction does not depend on the change in concentration of the reactants or products.
False (B)
What is the average rate of reaction in terms of concentration and time?
What is the average rate of reaction in terms of concentration and time?
change in concentration divided by time
The units of rate are expressed as concentration ______ time–1.
The units of rate are expressed as concentration ______ time–1.
Match the following types of reactions with their rate expression:
Match the following types of reactions with their rate expression:
What is the rate determining step in a reaction?
What is the rate determining step in a reaction?
Molecularity can be a fractional value.
Molecularity can be a fractional value.
What is the order of the reaction given the rate law r = k [A]^(1/2) [B]^2?
What is the order of the reaction given the rate law r = k [A]^(1/2) [B]^2?
The species IO- is known as an __________ in the reaction.
The species IO- is known as an __________ in the reaction.
Match the following terms with their definitions:
Match the following terms with their definitions:
How many steps are involved in the decomposition of hydrogen peroxide described?
How many steps are involved in the decomposition of hydrogen peroxide described?
For complex reactions, the molecularity is applicable.
For complex reactions, the molecularity is applicable.
If the concentration of molecule X is increased to three times, how will it affect the rate of formation of product Y in a second order reaction?
If the concentration of molecule X is increased to three times, how will it affect the rate of formation of product Y in a second order reaction?
What is the rate law in a chemical reaction?
What is the rate law in a chemical reaction?
Doubling the concentration of O2 while keeping NO constant will double the rate of formation of NO2.
Doubling the concentration of O2 while keeping NO constant will double the rate of formation of NO2.
In the given reaction 2NO(g) + O2(g) → 2NO2(g), what happens to the rate of reaction when the concentration of NO is doubled?
In the given reaction 2NO(g) + O2(g) → 2NO2(g), what happens to the rate of reaction when the concentration of NO is doubled?
The expression which relates the initial rate of a reaction to the concentration of reactants is called the rate _____ or rate expression.
The expression which relates the initial rate of a reaction to the concentration of reactants is called the rate _____ or rate expression.
Match the following experiments with their initial rates of formation of NO2:
Match the following experiments with their initial rates of formation of NO2:
From the given experimental data, how does the reaction rate relate to the concentrations of NO and O2 in this reaction?
From the given experimental data, how does the reaction rate relate to the concentrations of NO and O2 in this reaction?
The rate of a reaction can be influenced by changing the concentration of all reactants simultaneously.
The rate of a reaction can be influenced by changing the concentration of all reactants simultaneously.
What are the initial concentrations of NO and O2 in Experiment 3?
What are the initial concentrations of NO and O2 in Experiment 3?
What is the half-life period of a first order reaction with a rate constant of 60 s–1?
What is the half-life period of a first order reaction with a rate constant of 60 s–1?
After 10 years, the amount of 90Sr in the body will still be the same as the initial amount.
After 10 years, the amount of 90Sr in the body will still be the same as the initial amount.
What is the time required for 99% completion of a first order reaction in relation to the time for 90% completion?
What is the time required for 99% completion of a first order reaction in relation to the time for 90% completion?
For the decomposition of 90Sr, after 60 years, the remaining amount of the initial 1 mg will be ______ mg.
For the decomposition of 90Sr, after 60 years, the remaining amount of the initial 1 mg will be ______ mg.
Match the following decomposition rates with their periods:
Match the following decomposition rates with their periods:
What does the slope represent when plotting ln [R] against time (t)?
What does the slope represent when plotting ln [R] against time (t)?
The first order rate equation can be expressed as k = (2.303 * [R]0) / (t * [R]).
The first order rate equation can be expressed as k = (2.303 * [R]0) / (t * [R]).
What is the effect of taking the antilog of both sides of the equation ln [R] = -kt?
What is the effect of taking the antilog of both sides of the equation ln [R] = -kt?
The equation for calculating rate constant k in a first order reaction is k = __________.
The equation for calculating rate constant k in a first order reaction is k = __________.
Match the following components with their descriptions:
Match the following components with their descriptions:
Which of the following reactions is an example of first order kinetics?
Which of the following reactions is an example of first order kinetics?
Natural and artificial radioactive decay follows zero order kinetics.
Natural and artificial radioactive decay follows zero order kinetics.
What is the mathematical representation of a reaction that follows first order kinetics?
What is the mathematical representation of a reaction that follows first order kinetics?
What effect does lowering the activation energy (Ea) have on the rate of reaction?
What effect does lowering the activation energy (Ea) have on the rate of reaction?
The presence of a catalyst raises the activation energy required for a reaction.
The presence of a catalyst raises the activation energy required for a reaction.
Define the term 'steric factor' in the context of collision theory.
Define the term 'steric factor' in the context of collision theory.
The equation for the rate of reaction can be expressed as k = P Z A e^{-E_a / RT}. Here, P is the ______ factor.
The equation for the rate of reaction can be expressed as k = P Z A e^{-E_a / RT}. Here, P is the ______ factor.
Match the following reactions with their corresponding rate expression:
Match the following reactions with their corresponding rate expression:
What would be the order of the reaction for 2A + B ---> A2B if the rate is given as k[A][B]^2?
What would be the order of the reaction for 2A + B ---> A2B if the rate is given as k[A][B]^2?
For the decomposition of NH3 on a platinum surface, if the reaction is zero order, what is the relationship between the rate of reaction and the concentration of NH3?
For the decomposition of NH3 on a platinum surface, if the reaction is zero order, what is the relationship between the rate of reaction and the concentration of NH3?
In a reaction where k = 2.0 × 10–6 mol–2 L2 s–1, the initial rate when [A] = 0.1 mol L–1 and [B] = 0.2 mol L–1 is ______.
In a reaction where k = 2.0 × 10–6 mol–2 L2 s–1, the initial rate when [A] = 0.1 mol L–1 and [B] = 0.2 mol L–1 is ______.
Flashcards
Average Rate of Reaction
Average Rate of Reaction
The change in concentration of a reactant or product over a specific time interval, divided by the time interval.
Rate Units of Reaction
Rate Units of Reaction
Units of rate of a reaction are concentration time⁻¹, for example, mol L⁻¹s⁻¹, or atm s⁻¹ for gaseous reactions.
Instantaneous Rate
Instantaneous Rate
The rate of a reaction at a specific point in time. It is determined from the slope of the tangent to the concentration-time curve at that point.
Example 3.1 Calculation
Example 3.1 Calculation
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Reaction Rate Formula
Reaction Rate Formula
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Rate Law
Rate Law
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Rate Expression
Rate Expression
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Reaction Rate
Reaction Rate
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Initial Rate
Initial Rate
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Power on Concentration
Power on Concentration
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Stoichiometric Coefficient
Stoichiometric Coefficient
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Experiment 2 Rate
Experiment 2 Rate
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Order of reaction wrt NO
Order of reaction wrt NO
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Rate Determining Step
Rate Determining Step
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Rate Equation
Rate Equation
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Intermediate
Intermediate
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Elementary Reaction
Elementary Reaction
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Molecularity
Molecularity
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Order of Reaction
Order of Reaction
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Complex Reaction
Complex Reaction
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Second Order Kinetics
Second Order Kinetics
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Half-life period (t1/2)
Half-life period (t1/2)
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First-order reaction
First-order reaction
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Rate constant (k)
Rate constant (k)
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Radioactive decay
Radioactive decay
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Decomposition of N2O5
Decomposition of N2O5
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Activation Energy (Ea)
Activation Energy (Ea)
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Arrhenius Factor (A)
Arrhenius Factor (A)
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Rate of Reaction
Rate of Reaction
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Zero-Order Reaction
Zero-Order Reaction
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Second Order Reaction
Second Order Reaction
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Rate Law
Rate Law
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Order of Reaction
Order of Reaction
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Steric Factor (P)
Steric Factor (P)
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First-order rate equation
First-order rate equation
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Integrated rate law (1st order)
Integrated rate law (1st order)
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Rate constant (k)
Rate constant (k)
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ln[R] vs t plot
ln[R] vs t plot
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Half-life (t1/2)
Half-life (t1/2)
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log[R]0/[R] vs t plot
log[R]0/[R] vs t plot
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First-order reaction example
First-order reaction example
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Relationship between k and slope
Relationship between k and slope
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Study Notes
Reaction Rate Units
- The units for the rate of a reaction when the concentration is measured in mol L–1 and time in seconds are mol L–1 s–1.
- The average rate of a reaction is the change in concentration of a reactant or product over a specific time interval.
- The average rate of reaction can be calculated using the formula: average rate = (change in concentration) / (change in time).
Rate Law and Order of Reaction
- The rate law is an equation that describes the relationship between the rate of a reaction and the concentrations of the reactants.
- The order of a reaction with respect to a reactant is the exponent of the reactant's concentration term in the rate law.
- For a reaction with the rate law r = k [A]^(1/2) [B]^2, the overall order of the reaction is 2.5. This is calculated by adding the exponents of the reactant concentrations (1/2 + 2 = 2.5).
Rate Determining Step
- The rate determining step is the slowest step in a multi-step reaction and determines the overall rate of the reaction.
- The molecularity of a reaction refers to the number of molecules that collide and react in the rate determining step.
- The molecularity of a reaction can be determined from the rate law for an elementary step.
Catalyst and Intermediates
- A catalyst is a substance that increases the rate of a reaction without being consumed in the process.
- An intermediate is a species that is formed and consumed during a reaction but does not appear in the overall balanced equation.
- In the reaction involving IO-, the species IO- is known as an intermediate.
Complex Reactions
- Complex reactions involve multiple steps and can have different molecularities for each step.
- The molecularity of a complex reaction can be determined by examining the individual steps in the reaction mechanism.
Effect of Concentration on Reaction Rate
- In a second order reaction, the rate of the reaction is proportional to the square of the concentration of the reactant. Therefore, tripling the concentration of a reactant will increase the rate of formation of the product by a factor of 9.
- In the reaction 2NO(g) + O2(g) → 2NO2(g), doubling the concentration of NO will quadruple the rate of the reaction. This is because the rate of the reaction is second order with respect to NO.
Half-Life of a Reaction
- The half-life of a reaction is the time it takes for the concentration of a reactant to decrease to half its initial value.
- The half-life for a first-order reaction is independent of the initial concentration and can be calculated using the formula: t1/2 = 0.693/k, where k is the rate constant.
Collision Theory
- Collision theory states that for a reaction to occur, reactant molecules must collide with sufficient energy and correct orientation.
- The activation energy (Ea) is the minimum energy required for a reaction to occur.
- The steric factor (P) in collision theory accounts for the orientation of molecules during a collision.
- The equation k = P Z A e^(-E_a / RT) relates the rate constant (k) to the steric factor (P), the collision frequency (Z), the frequency factor (A), the activation energy (Ea), the gas constant (R), and the temperature (T).
Zero and First Order Reactions
- A zero-order reaction has a rate that is independent of the concentration of the reactants.
- A first-order reaction has a rate that is directly proportional to the concentration of one reactant.
- The equation for calculating the rate constant k in a first-order reaction is k = (ln [R]0 - ln [R]) / t, where [R]0 is the initial concentration, [R] is the concentration at time t, and t is the time.
Activation Energy and Catalysis
- Lowering the activation energy (Ea) increases the rate of a reaction, as it reduces the energy barrier that molecules must overcome to react.
- Catalysts speed up reactions by providing an alternative reaction pathway with a lower activation energy.
Summary of Key Concepts
- The rate of a reaction is determined by the rate law, which expresses the relationship between the rate of a reaction and the concentrations of reactants.
- The order of a reaction is determined by the exponents in the rate law and describes how the rate of a reaction changes with the concentrations of reactants.
- The rate of a reaction can be affected by factors such as temperature, concentration, and the presence of a catalyst.
- Collision theory explains the rate of a reaction in terms of collisions between reactant molecules.
- The steric factor accounts for the orientation of molecules during collisions.
- The activation energy is the minimum energy required for a reaction to occur.
- Catalysts increase the rate of a reaction by providing an alternative reaction pathway with a lower activation energy.
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Description
This quiz covers the fundamental concepts of chemical kinetics, including reaction rates, molecularity, and order. Explore how factors like concentration, temperature, and catalysts impact reactions, and learn to derive integrated rate equations. Test your understanding of collision theory and the feasibility of reactions.
