Course Hero Logo

1B,EXP 0,Kinetics,F19.pdf - CHEMISTRY 1B Experiment 0...

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 1 - 2 out of 10 pages.

CHEMISTRY 1BExperiment 0KineticsIntroduction.Kinetics is the study of the rates of chemical reactions.In this experiment you will bestudying the rate of the redox reaction between the peroxidisulfate ion and the iodide ion in aqueous solution.You will investigate how the rate changes when you vary the concentration of the reactants and also whenyou vary the temperature.You will use these experimental measurements to determine the rate law and tocalculate the activation energy for the reaction.You can read about the basic ideas of kinetics- including ratelaws, rate constants, mechanisms, and activation energy- in the Kinetics chapter of your textbook.The Reaction.The reaction that you will measure the rate of is the reaction between peroxydisulfate ion(often called persulfate for short) and iodide ion :(rxn #1)In order to time the progress of this reaction, you will run a "clock" reaction simultaneously in the samesolution.The clock reaction is a rapid reaction between the thiosulfate ion and iodine:(rxn #2).Note that iodine is produced in reaction #1 andconsumed in reaction #2.Here's how the reaction timing works.The initial reaction mixture will contain relatively large amounts ofpersulfate and iodide; a small, precisely known amount of thiosulfate; plus a few drops of starch indicator(which will turn blue in the presence of iodine).When all the reagents are mixed together at time zero,reaction #1 will begin and I2will be created as a product.But all of the I2created will quickly be consumedin reaction #2 and it will not have time to interact with the starch.This will be the situation until all thethiosulfate (S2O32-) is used up.Once the thiosulfate is gone, the I2created in reaction #1 will begin toaccumulate in the solution and the iodine and starch will stick together to make a blue-colored complex.So,when your reaction solution turns blue, you are really measuring the time it takes for all the thiosulfate to beconsumed. Because you know precisely the moles of thiosulfate you started with, you should be able to usethe stoichiometric relationship between thiosulfate and persulfate to calculate how many moles of persulfatewere consumed in that same interval of time, which will allow you to calculate the initial rate of the reaction.(Note that during this short time interval, the [S2O82–] and the [I] change very little compared to their initialconcentrations.)You will then repeat the experiment using different initial concentrations of persulfate and iodide to see howthat affects the rate of the reaction.This information will allow you to determine the experimental rate lawfor the reaction.Finally, you will repeat the experiment at different temperatures to see how that affects therate of reaction and the rate constant, k.By plotting a graph of ln k as a function of 1/T, you will be able tocalculate the activation energy for the reaction.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 10 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Spring
Professor
Ansari,A
Tags
Chemical reaction, Rate equation, beaker

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture