At 21 °C, a solution of 12 mL each of 0.00200 M Fe3+ and 0.001000 M SCN- was mixed and brought to 25.0 mL with 0.1 M HNO3. The absorbance at 450 nm was measured to be 0.350 (A450 = 0.350). This solution was then heated to 45 °C and the absorbance at 450 nm was measured to be 0.142 (A450= 0.142). Is the reaction: Fe3+(aq) + SCN -(aq) → FeSCN2+(aq) exothermic or endothermic? Explain.

At 21 °C, a solution of 12 mL each of 0.00200 M Fe3+ and 0.001000 M SCN- was mixed and brought to 25.0 mL with 0.1 M HNO3. The absorbance at 450 nm was measured to be 0.350 (A450 = 0.350). This solution was then heated to 45 °C and the absorbance at 450 nm was measured to be 0.142 (A450= 0.142). Is the reaction: Fe3+(aq) + SCN -(aq) → FeSCN2+(aq) exothermic or endothermic? Explain.

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter14: Applications Of Ultraviolet-visible Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 14.9QAP

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