Kinetics Summery
Big Idea #4: Rates of chemical reactions are determined by details of the molecular collisions.
Chemical changes occur over a wide range of time scales. Practically, the manner in which the rate of change is observed is to measure changes in concentration of reactant or product species as a function of time. There are a number of possible factors that influence the observed speed of reaction at the macroscopic level, including the concentration of reactants, the temperature, and other environmental factors. Measured rates for reactions observed at the macroscopic level can generally be characterized mathematically in an expression referred to as the rate law. In addition to these macroscopic -level characterizations, the progress of reactions at the particulate level can be connected to the rate law. Factors that influenced the rate of reaction, including speeding of the reaction by the use of a catalyst, can be delineated as well.
Enduring Understanding 4A: Reaction rates that depend on temperature and other environmental factors are determined by measureing changes in concentrations of reactants or products over time.
Enduring Understanding 4B: Elementary reactions are mediated by collisions between molecules. Only collisions having sufficient energy and proper relative orientation of reactants lead to products.
Enduring Understanding 4C: Many reactions proceed via a series of elementary reactions.
Enduring Understanding 4D: Reaction rates may be increased by the presence of a catalyst.
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Objectives:
Reaction mechanics
- Students will be able to determine what components of the collision theory are needed to spark a reaction
- Students will be able to describe the conditions needed to speed up a chemical reaction as related to the collision theory.
Tracking Rate
- Students will be able to set up a reaction to test the rate of a reaction.
- Students will be able to determine the appearance or disappearance of individual components of a chemical reaction.
Rate law and initial rate
- Students will be able to write the rate laws for a specific reaction
- Students will be able to determine the order of the reaction. (concentration vs. initial rate)
- Students will be able to determine the rate constant and its units.
- Students will be able to use the rate law to predict the initial rate at various concentrations.
Integrated Rate law
- Using the integrated rate laws students will be able to solve for various concentrations and times as a reaction progresses.
- Students will be able to describe and calculate half lives of 1st order reactions.
- Students will be able to graph each type of order of reactions.
- Students will be able to determine the order of a reaction based on the graphical representations.
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