Question

Determination of an Activation Energy-An Application of Kinetics Postlab B Date Name CHM123L section Instructor 1. Label the energy diagrams with the following: Reactants. Products, Activation energy include arrow) Heat absorbed or Heat released include arrow) Potential Energy Potential Energy Reaction Progress Reaction Progress Exothermic Endothermic reaction reaction 2. During this experiment, the absorbance of solutions of iron (11) phenanthroline was monitored at various temperatures. At all temperatures the absorbance of the solution decreased over time. a. Explain what was happening to the iron (1) phenanthroline complex ion to account for the decrease in absorbance b. Look at your data from page 10-9. Subtract the absorbance value from your first and last measurement to determine the change in absorbance during the course of the experiment. Show work c. Use the change in absorbance from above and the molar absorptivity for the iron (II) phenanthroline complex ion, E = 1.14 x 10(mol cm), along with the Beer-Lambert Law to calculate the change in concentration during the experiment. Show work.

Answer 1

1. A reaction always go from reactant to products. Activation energy = Energy of transition state - Energy of C reactant. Heat absorbed/released - Energy 9 product - Energy I recckant Exothermic reaction: o energy is released Reactant has higher energy than - products Endothermic reaction : energy is absorbed • Product has higher energy than reactants. Energy A Activation Energy actants L Activation - Energy _*----- Heat released -- Products Potential Energy Proclucts 1 Heat absorbed Polential Reactants Reaction progress Exothermic reaction Reaction Endothermic progress reaction