1 / 14

Chemical Kinetics

Chemical Kinetics. Reaction rate - the change in concentration of reactant or product per unit time. Factors Affecting Rates. Temperature Concentration of reactants Particle size Presence of a catalyst. Rates.

Download Presentation

Chemical Kinetics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chemical Kinetics • Reaction rate - the change in concentration of reactant or product per unit time.

  2. Factors Affecting Rates • Temperature • Concentration of reactants • Particle size • Presence of a catalyst

  3. Rates • Average rates - the difference in concentration over a set amount of time. Table 12.2 • Instantaneous rates - calculated from the slope of the line tangent to the curve at a certain point.

  4. Reaction rates • Rates are not constant. • Rates vary with time because concentrations vary with time.

  5. Rate Laws • Rate = k[A]n[B]m[C]p • k = rate constant • n,m,p = order ; must be determined by experiment.

  6. Differential rate law • Expresses how a rate depends on concentration. • Often this is just called the rate law.

  7. Integrated rate law • Expresses how the concentration depends on time.

  8. Reaction Mechanism • The series of elementary steps by which a reaction occurs. • An elementary step is a step whose rate law can be determined from its molecularity.

  9. Molecularity • The number of species that must collide to produce the reaction in that step. • Unimolecular involves one molecule. • Bimolecular and termolecular involve 2 and 3 species respectively

  10. Intermediate • A species that is neither a reactant or a product. This species is produced and consumed in the reaction.

  11. Rate Determining Step • This is the slowest step of the mechanism. The reaction can only proceed as fast as this rate determining step will allow.

  12. Requirements of Mechanisms • The sum of the elementary steps must give the overall balanced equation. • The mechanism must agree with the experimentally determined rate law. The rate determining step.

  13. Collision model for kinetics • Reactant molecules must collide in order to react. • Concentration • Particle size • Temperature • Molecular orientation

  14. Requirements for reaction • The collision energy must equal or exceed the activation energy. • The orientation of the reactants must allow the formation of new bonds.

More Related