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Questions and Answers
What is the area of chemistry concerned with reaction rates called?
What is the area of chemistry concerned with reaction rates called?
- Thermodynamics
- Physical chemistry
- Chemical kinetics (correct)
- Analytical chemistry
The rate of a chemical reaction is determined solely by the increase in concentration of the products.
The rate of a chemical reaction is determined solely by the increase in concentration of the products.
False (B)
What formula expresses the rate of a chemical reaction?
What formula expresses the rate of a chemical reaction?
Rate = ∆c/∆t
In the reaction A → B, the concentration of A decreases during the time interval, therefore ∆[A] is a ______ quantity.
In the reaction A → B, the concentration of A decreases during the time interval, therefore ∆[A] is a ______ quantity.
Match the following examples with their respective rates of reaction:
Match the following examples with their respective rates of reaction:
Which reaction would likely have the fastest rate?
Which reaction would likely have the fastest rate?
Chemical kinetics only studies reactions that occur within a few seconds.
Chemical kinetics only studies reactions that occur within a few seconds.
What does ∆c represent in the rate of reaction formula?
What does ∆c represent in the rate of reaction formula?
What is the average rate of formation of NO2 during the time period 300 – 400 s?
What is the average rate of formation of NO2 during the time period 300 – 400 s?
The concentration of NO2 increases with time as the reaction proceeds.
The concentration of NO2 increases with time as the reaction proceeds.
What is the molarity of O2 produced when [N2O5] = 1.20 × 10–2 mol L−1 at 300 s?
What is the molarity of O2 produced when [N2O5] = 1.20 × 10–2 mol L−1 at 300 s?
The molarity of NO2 produced per liter is calculated using the factor of _______ moles of NO2 per mole of N2O5.
The molarity of NO2 produced per liter is calculated using the factor of _______ moles of NO2 per mole of N2O5.
Match the following terms with their definitions:
Match the following terms with their definitions:
Which statement best explains why the rate of reaction decreases over time?
Which statement best explains why the rate of reaction decreases over time?
How is the average rate of O2 formation determined during a specific time period?
How is the average rate of O2 formation determined during a specific time period?
At time t = 350 s, the rate of formation of NO2 can be calculated using the initial concentration of N2O5.
At time t = 350 s, the rate of formation of NO2 can be calculated using the initial concentration of N2O5.
What is the rate expression for the reaction 3O2(g) → 2O3(g)?
What is the rate expression for the reaction 3O2(g) → 2O3(g)?
The rate of a reaction is always expressed as a positive quantity without needing adjustments for reactant disappearance.
The rate of a reaction is always expressed as a positive quantity without needing adjustments for reactant disappearance.
If the rate of disappearance of I− is 2.0 × 10–5 mol L–1 s–1, what would be the rate of appearance of OI− in the reaction I−(aq) + OCl−(aq) → Cl−(aq) + OI−(aq)?
If the rate of disappearance of I− is 2.0 × 10–5 mol L–1 s–1, what would be the rate of appearance of OI− in the reaction I−(aq) + OCl−(aq) → Cl−(aq) + OI−(aq)?
The rate of formation of N2 from the reaction 2NO(g) + 2H2(g) → N2(g) + 2H2O(g) can be expressed as ___.
The rate of formation of N2 from the reaction 2NO(g) + 2H2(g) → N2(g) + 2H2O(g) can be expressed as ___.
Match the following reactions with their correct rate expressions:
Match the following reactions with their correct rate expressions:
For the reaction aA + bB → cC + dD, which expression correctly represents the rate?
For the reaction aA + bB → cC + dD, which expression correctly represents the rate?
An observable property that can indicate the rate of reaction must be something that can be directly calculated as a concentration.
An observable property that can indicate the rate of reaction must be something that can be directly calculated as a concentration.
What common observable properties can be used to determine the change in concentration over time?
What common observable properties can be used to determine the change in concentration over time?
What is the term for the minimum amount of energy needed for a reaction to occur?
What is the term for the minimum amount of energy needed for a reaction to occur?
Ineffective collisions can result in the formation of desired products.
Ineffective collisions can result in the formation of desired products.
What factor increases the reaction rate by causing particles to collide more frequently?
What factor increases the reaction rate by causing particles to collide more frequently?
The reaction between an acid and a base, such as HCl and NaOH, occurs rapidly compared to the decomposition of ________.
The reaction between an acid and a base, such as HCl and NaOH, occurs rapidly compared to the decomposition of ________.
Match the following reactions with their characteristics:
Match the following reactions with their characteristics:
Which factor does NOT affect the rate of a chemical reaction?
Which factor does NOT affect the rate of a chemical reaction?
Homogeneous reactions occur in different phases.
Homogeneous reactions occur in different phases.
What type of collisions lead to reactions forming new products?
What type of collisions lead to reactions forming new products?
What type of reaction occurs only at the interface between two phases?
What type of reaction occurs only at the interface between two phases?
An increase in concentration of reactants generally decreases the rate of reaction.
An increase in concentration of reactants generally decreases the rate of reaction.
What is the effect of temperature on the rate of reaction?
What is the effect of temperature on the rate of reaction?
A __________ is a substance that increases the rate of a reaction by providing a different reaction mechanism with lower activation energy.
A __________ is a substance that increases the rate of a reaction by providing a different reaction mechanism with lower activation energy.
Match the following factors with their effects on reaction rates:
Match the following factors with their effects on reaction rates:
Which of the following statements is true regarding the effect of pressure on reaction rate?
Which of the following statements is true regarding the effect of pressure on reaction rate?
Finely divided solids react more slowly than larger bodies of the same substance.
Finely divided solids react more slowly than larger bodies of the same substance.
What is activation energy in the context of chemical reactions?
What is activation energy in the context of chemical reactions?
What is the initial rate of reaction calculated from?
What is the initial rate of reaction calculated from?
According to collision theory, all collisions between molecules result in a reaction.
According to collision theory, all collisions between molecules result in a reaction.
What must happen for a chemical reaction to take place according to collision theory?
What must happen for a chemical reaction to take place according to collision theory?
The rate of reaction is directly proportional to the number of ______ per second.
The rate of reaction is directly proportional to the number of ______ per second.
At what time is the instantaneous rate of reaction calculated in the given example?
At what time is the instantaneous rate of reaction calculated in the given example?
The slope of the tangent drawn to the curve represents the instantaneous rate of reaction.
The slope of the tangent drawn to the curve represents the instantaneous rate of reaction.
In the provided gas-phase reaction, what compounds are being produced?
In the provided gas-phase reaction, what compounds are being produced?
Flashcards
Chemical Kinetics
Chemical Kinetics
The study of how fast chemical reactions happen and the factors that influence their speed.
Rate of reaction
Rate of reaction
The change in the concentration of a reactant or product over a period of time.
Half-life
Half-life
The time it takes for the concentration of a reactant to decrease to half its initial value.
Factors affecting reaction rate
Factors affecting reaction rate
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Temperature effect
Temperature effect
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Concentration effect
Concentration effect
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Surface area effect
Surface area effect
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Catalyst
Catalyst
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Why does the rate of reaction decrease over time?
Why does the rate of reaction decrease over time?
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What is the rate of reaction?
What is the rate of reaction?
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What is the average rate of reaction?
What is the average rate of reaction?
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What is the instantaneous rate of reaction?
What is the instantaneous rate of reaction?
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How do you find the instantaneous rate of reaction?
How do you find the instantaneous rate of reaction?
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How do concentrations change during a reaction?
How do concentrations change during a reaction?
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What is the relationship between the chemical equation and the rate of reaction?
What is the relationship between the chemical equation and the rate of reaction?
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How do you calculate the rate of reaction from the concentration of reactants and products?
How do you calculate the rate of reaction from the concentration of reactants and products?
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Instantaneous Rate
Instantaneous Rate
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Initial Rate
Initial Rate
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Collision Theory
Collision Theory
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Effective Collisions
Effective Collisions
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Ineffective Collisions
Ineffective Collisions
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Rate Expression for Reactants
Rate Expression for Reactants
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Rate Expression for Products
Rate Expression for Products
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Stoichiometry and Rate
Stoichiometry and Rate
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General Rate Expression
General Rate Expression
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Determining Reaction Rate
Determining Reaction Rate
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Rate of Reaction Measurement
Rate of Reaction Measurement
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Rate of Reaction Summary
Rate of Reaction Summary
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Molecular Orientation
Molecular Orientation
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Activation Energy
Activation Energy
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Nature of Reactants
Nature of Reactants
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Surface Area
Surface Area
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Homogeneous Reactions
Homogeneous Reactions
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Heterogeneous Reactions
Heterogeneous Reactions
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Study Notes
Chemical Kinetics Introduction
- Chemical reactions occur at varying speeds
- Some reactions take days, others seconds
- Chemical kinetics studies reaction rates
- "Kinetic" implies movement or change
- Chemical kinetics measures how fast reactant/product concentrations change
Reaction Rate
- Measures the change in reactant or product concentration per unit time
- Determined by monitoring reactant decrease or product increase
- Expressed as ∆c/∆t
- ∆c = Change in concentration, ∆t = Change in time
- Rate is positive, ∆[A]/∆t or -∆ [A]/∆t
Rate Expressions for Complex Reactions
- For more complex reactions, rate expressions consider stoichiometric coefficients
- Rate = -1/a∆[A]/∆t = 1/b ∆[B]/∆t = 1/c ∆[C]/∆t= 1/d ∆[D]/∆t
Determining Reaction Rate
- Observable property changes over time (e.g., color, pressure, mass)
- Measurements track concentration changes over time
- Example: Thermal decomposition of Nâ‚‚Oâ‚… to NOâ‚‚ + Oâ‚‚
- Concentration changes can be monitored using pressure, color, or other measurable properties
- Rate is calculated using concentration data, and time
- Average rate is calculated using two concentration values in time interval ∆t
Instantaneous Rate of Reaction
- Rate at a specific time, t
- Calculated from the slope of a tangent line to a concentration vs. time graph at point t.
- Initial rate is the slope of a tangent at t = 0
Factors Affecting Reaction Rates
- Nature of Reactants: Some reactions are faster than others due to chemical nature
- Surface Area: Larger surface area increases reaction rate for heterogeneous reactions
- Concentration: Higher concentration of reactants leads to more frequent collisions, hence faster reaction
- Temperature: Higher temperatures increase kinetic energy, leading to more frequent and energetic collisions, and thus a faster reaction
- Presence of a Catalyst: Catalysts reduce activation energy; speeding up the reaction but are not consumed in the process.
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