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Chemistry 14: 1-2

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Reaction Rates

Chapter 14: 1-2 Homework

Reading Preparation

Textbook assignment: Read Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 14: Sections 1 and 2.

Study Notes
  1. 14.1 The rate of a reaction can be measured by the change in concentration of the reactants or products as time passes. By convention, concentration is represented with brackets: [NO2] means concentration of nitrogen dioxide, so the formula takes the form rate = Δ[substance]/Δt. The reaction rate itself will change over time, usually decelerating with decreasing reactant concentration. The rate of disappearance of reactants will be balanced by the rate of appearance of products, in the ratio of moles specified by the stoichiometric coefficients of the balanced reaction equation.
  2. 14.2 Reaction rates can be affected by several factors, including concentration, temperature, and the presence of catalysts that can lower the activation energy level required for a reaction to occur.

Key Formula

Rate of Reaction rate   =   Δ c Δ t   = Δ [ substance ] Δ t Δc: change in concentration
Δt: period of time
General reaction rate equation, the relative rates are aA   +   bB   cC   +   Dd   1 a Δ A Δ t   = 1 b Δ B Δ t   =   + 1 c Δ C Δ t   =   +   1 d Δ D Δ t   A, B: reactants
C, D: products
a, b, c, d: stoichiometric coefficients
Δt: time over which reaction occurs

Web Lecture

Read the following weblecture before chat: Measuring and Quantifying Reaction Rates

Study Activity

Videos for Chapter 14: The Rates of Chemical Reactions

Review the Videos at Thinkwell Video Lessons.

  • Under "Chemical Kinetics"
    • Reaction Rates
      • An Introduction to Reaction Rates
      • Rate Laws: How the Reaction Rate Depends on Concentration
      • Determining the Form of a Rate Law

Use the Rates of Reactions Simulation Rates of Reactions Simulation to explore a single collision.

  • Accept the default initial scenario.
    • Pull the red nob at the bottom of the plunger down and let go to release the first molecule into the chamber. Observe the interactions. Does the first molecule break and reform with the second molecule?
    • Vary the temperature. Can you break up the initial molecule?
    • Look at the Separation distance and the potential energy graph for the first reaction. How much does potential energy need to increase for the reaction to occur?
  • Try each of the reactions. How do they differ? What changes do you have to make in temperature (aka available energy) for the reaction to take place?

Chat Preparation Activities

Chapter Quiz

(Aligns to) AP #10 GUIDED INQUIRY — Determination of solution concentration of copper sulfate solutions using visual colorimetry. — Phase III

Use your set of calibrated solutions to estimate the molarity of a sample of unknown concentration. Submit a formal report of your work for this laboratory experience.