Amounts of iodine dissolved in aqueous solution, Iz(aq), can be determined by titration with thiosulfate ion (S2O³¯). The thiosulfate ion is oxidized to S40; while the iodine is reduced to iodide ion. Starch is used as an indicator because it has a strong blue color in the pres- ence of dissolved iodine. (a) Write a balanced equation for this reaction. (b) If 56.40 mL of 0.100 M S20;¯ solution is used to reach the endpoint of a titration of an unknown amount of iodine, calculate the number of moles of iodine originally present. (c) Combine the appropriate half-cell potentials from Appendix E with thermodynamic data from Appen- dix D for the equilibrium I2 (s)=1½(aq) to calculate the equilibrium constant at 25°C for the reaction in part (a).

Amounts of iodine dissolved in aqueous solution, Iz(aq), can be determined by titration with thiosulfate ion (S2O³¯). The thiosulfate ion is oxidized to S40; while the iodine is reduced to iodide ion. Starch is used as an indicator because it has a strong blue color in the pres- ence of dissolved iodine. (a) Write a balanced equation for this reaction. (b) If 56.40 mL of 0.100 M S20;¯ solution is used to reach the endpoint of a titration of an unknown amount of iodine, calculate the number of moles of iodine originally present. (c) Combine the appropriate half-cell potentials from Appendix E with thermodynamic data from Appen- dix D for the equilibrium I2 (s)=1½(aq) to calculate the equilibrium constant at 25°C for the reaction in part (a).

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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