The amount of Fe in a 0.4891-g sample of an ore was determined by a redox titration with K2Cr,0,. All the Fe was initially converted to Fe2+ followed by titration with 0.02153 M K,Cr207, which required 36.92 mL. The titration reaction is: Cr,0,2- + 6Fe?+ + 14H* - 20r+ + 6FE3+ + 7H20 How many millimoles of Fe2+ is present in the sample? a) 4.769 mmol b) 2.385 mmol c) 1.590 mmol d) 0.3974 mmol e) 0.1325 mmol If Fe in the sample exists as Fe203 (159.69 g/mol), what is the percentage by weight Fe2O3? a) 25.97% b) 38.93% c) 52.91% d) 76.45% e) 77.86% Based on the titration reaction, which of the following statements is TRUE? a) The species oxidized is Cr20,2-. b) The oxidation number of iron decreased. c) Chromium (VI) is converted to chromium (III). d) The reaction occurs under neutral conditions. e) None of the above.

The amount of Fe in a 0.4891-g sample of an ore was determined by a redox titration with K2Cr,0,. All the Fe was initially converted to Fe2+ followed by titration with 0.02153 M K,Cr207, which required 36.92 mL. The titration reaction is: Cr,0,2- + 6Fe?+ + 14H* - 20r+ + 6FE3+ + 7H20 How many millimoles of Fe2+ is present in the sample? a) 4.769 mmol b) 2.385 mmol c) 1.590 mmol d) 0.3974 mmol e) 0.1325 mmol If Fe in the sample exists as Fe203 (159.69 g/mol), what is the percentage by weight Fe2O3? a) 25.97% b) 38.93% c) 52.91% d) 76.45% e) 77.86% Based on the titration reaction, which of the following statements is TRUE? a) The species oxidized is Cr20,2-. b) The oxidation number of iron decreased. c) Chromium (VI) is converted to chromium (III). d) The reaction occurs under neutral conditions. e) None of the above.

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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