Chem 113 1st Edition Lecture 15 Outline of Last Lecture I. Probability of a mechanismII. Determining rate law from multi-step reactionsIII. Decomposition of O3 to O2IV. Catalysis: speeding up a reactionOutline of Current Lecture V. Chemical EquilibriumVI. The synthesis of AmmoniaVII. The Equilibrium Constant (K)VIII. K and the extent of reactionCurrent LectureI. Chemical Equilibriuma. Our understanding of thermodynamics, kinetics and equilibrium of chemical reactions helps us to develop the most efficient process for the production of NH3b. Reactions are reversiblei. The reaction reaches a state of equilibrium between the reactants and the productsc. At equilibriumi. [reactant]=constant (not changing)ii. [product]=constant (not changing)iii. Rateforward=Ratereverse; k1 vs. k-1d. Chemical equilibrium= dynamic state (molecular level)i. Reactions continue to occurThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. No net change on the macroscopic levelII. The synthesis of Ammoniaa. Ammonia is synthesized industrially via the Haber-Bosch processb. Ways of increases the rate i. Increasing temperature 1. Increases the average kinetic energy in the system’2. Increases the rate constant (k)ii. Adding a catalyst1. Lowers the activation energy (Ea) via alternate reaction mechanismIII. The Equilibrium Constant (K)a. The ratio of constants (k in individual reaction rates) gives a new constant the Equilibrium Constant (K)i. Base on the equation: N2O4 (g)2NO2 (g)ii.K=kfwdkrev=[NO2]eq2[ N2O4]eqIV. K and the extent of reactiona. K reflects a particular ratio of product concentrations to reactant concentrations for a reactionb. K therefore indicates the extent of a reaction (how far a reaction proceeds towards the products at a given temperature)c. A small value for K (<<1) indicates that the reaction yields little product before reaching equilibrium. The reaction favors the reactants (lies far to the left)d. A large value for K (>>1) indicates that the reaction reaches equilibrium with verylittle reactant remaining. The reaction favors the products (lies far to the
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