CH302 Chapter 6 notes part 2 K and Reaction Extent K > 1Equilibrium lies to the right: System will contain more product than reactant. (K >>> 1: reaction goes to completion) K < 1Equilibrium lies to the left: System will contain more reactant than product. (K <<< 1: very little reaction occurs) Reaction Quotient Looks very similar to the expression for K, BUT the concentrations are those of the INITIAL setup... For a simple reversible reaction: jA + kB « lC + mD The reaction quotient is: Q = [C]l[D]m[X] = INITIAL concentration of X [A]j[B]kQ vs. K: Shift in System Q = KReaction IS already at equilibrium: no shift. Q > KProduct concentration is too high: Reaction must shift to the left to reach equilibrium Q < KProduct concentration is too low: Reaction must shift to the right to reach equilibrium Example K = 49 at 450oC for this reaction: H2(g)+ I2(g)↔2HI(g)If 0.22 mole of I2, 0.22 mole of H2, and 0.66 mole of HI were put into an evacuated 1.00-liter container, would the system be at equilibrium? If not, what must occur to establish equilibrium? Equilibrium Calculations We are now ready for the tricky stuff! Two main types: 1. Given K and initial concentrations, find equilibrium concentrations. 2. Given initial concentrations and one of the equilibrium concentrations, find K BOTH involve setting up ICE tables (Initial, Change, Equilibrium) What follows are several examples to be done in class. We had to get to this point to be able to 'put it all together'
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