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Questions and Answers
What is the average rate of change of [D] over the first 30 minutes?
What is the average rate of change of [D] over the first 30 minutes?
Which of the following statements about the rate of change is correct?
Which of the following statements about the rate of change is correct?
What is the relationship between the rate of consumption of Ag+(aq) and the rate of formation of [Ag(CN)2]−(aq)?
What is the relationship between the rate of consumption of Ag+(aq) and the rate of formation of [Ag(CN)2]−(aq)?
Which of the following is the correct expression for the instantaneous rate of change of D?
Which of the following is the correct expression for the instantaneous rate of change of D?
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What is the relationship between the initial rates of A and D?
What is the relationship between the initial rates of A and D?
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How does the rate of loss of CN−(aq) relate to the rate of loss of Ag+(aq)?
How does the rate of loss of CN−(aq) relate to the rate of loss of Ag+(aq)?
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Why is it important to properly balance a chemical equation when determining relative rates?
Why is it important to properly balance a chemical equation when determining relative rates?
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What is the difference between average rate and instantaneous rate?
What is the difference between average rate and instantaneous rate?
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Study Notes
Chemical Kinetics: Reaction Rates
- Respect Colleagues: Turn off cell phones, put aside personal materials, and refrain from using electronic devices (iPods, laptops, PDAs) for non-class-related activities during lectures and recitations.
General Chemistry II (Chem 1780-1) - January 22, 2025
- Course: General Chemistry II (Chem 1780-1)
- Date: Wednesday, January 22, 2025
- Topic: Chemical Kinetics: Reaction Rates (Module 1)
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Subtopic: Reaction Rates
- Understanding the distinctions between rate of change, rate of consumption, and rate of formation.
- Calculating relative rates using balanced chemical equations.
- Next Topic: Kinetics: Rate laws; Method of Initial Rates
- Assessments: Lecture Questions (Canvas; Due Jan 25 at 11:59 pm). OWL-01 and 02 (Saturday; single session only).
Average Reaction Rates
- Definition: Average rate of change is calculated as the change in concentration over the change in time.
- For a reaction A → D
- Average rate of Change of D over first 30 minutes (Δ[D]/Δt) = +0.020 M/min
- Average Rate of Change of A: (Δ[A]/Δt) = −0.020 M/min (negative because A is consumed).
- Rate of Formation (Product): Positive (e.g., +0.020 M/min)
- Rate of Consumption (Reactant): Negative (e.g., -0.020 M/min)
Instantaneous Reaction Rates
- Definition: Instantaneous rate measures the reaction rate at a specific moment in time.
- Representation: It’s represented by the instantaneous slope of the concentration vs. time graph, calculated as the derivative (d[D]/dt).
- Positive slope D > 0: Formation of product.
- Negative slope A < 0: Consumption of reactant.
- Fastest rate: (time difference or dt) approaching zero (Δt → 0).
Relative Reaction Rates
- Balanced Reactions: Essential for calculating relative rates (e.g., aA + bB → dD + eE).
- Relationships: The relationship between the rates of consumption of reactants and the rates of formation of products are proportional to the stoichiometric coefficients in the balanced reaction.
- Example: In the reaction: Ag⁺(aq) + 2CN⁻(aq) → [Ag(CN)₂]⁻(aq)
- Rate of consumption of CN⁻(aq) = 2 * Rate of consumption of Ag⁺(aq)
- Relative Rates = − 1/1 Δ[A]/Δt = − 1/2 Δ[CN⁻]/Δt
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Description
This quiz focuses on the topic of Chemical Kinetics, specifically reaction rates, as part of General Chemistry II (Chem 1780-1). You'll explore concepts such as the average rate of change, rate of consumption, and rate of formation. Prepare to calculate relative rates using balanced chemical equations and apply your understanding in various assessment scenarios.
