Chem 130 Chp. 15

Chp. 15 Chemical equilibrium Occurs when a reaction and its reverse reaction (opposing reactions) proceed at the same set At equilibrium the rate at which harvest-festivals are produced from reactants equals the rate at which reactants are produced from products At equilibrium a particular dimension of concentration terms equals a constant The composition of an equilibrium mixture does not win over with duration Kc equilibrium constant 15. 2 Law of mass action expresses the relationship between the concentrations of the reactants and products enter at equilibrium 5. 3 * * LARGE VALUE OF Kc Equilibrium mixture contains more products than reactants = product face (right side) K 1 *SMALL VALUE OF Kc Equilibrium mixture contains less products than reactants = reactant side (left side) K 1 The equilibrium-constant expression for a reaction written in one flush is the reciprocal of the one for the reaction written in the reverse direction Multiplying all the stoichiometric coeffi cients by a number gives the equilibrium constant for the original reaction raised to that number 15. 4Concentrations of PURE SOLIDS and LIQUIDS DO non appear in equilibrium expression L S 15. 5 ICE TABLS 15. 6 15. 7 Le chateliers principle IF a system at equilibrium is disturbed by a change in temperature, pressure, or the concentration of one of the components, the system will shift its equilibrium position so as to counteract the effect of the disturbance % of NH3 at equilibrium decreases with increasing temperature and maturations with increasing pressure * * endoergic reaction increase in temperature shifts equilibrium to right reactant bsorbs heat change magnitude T results in an increase K * Exothermic reaction Temperature increase shifts equilibrium to left product gives off heat Increasing T results in decreasing K * * Increasing pressure ( decreasing volume) equilibrium shifts in the direction producing the smaller number of moles of gas will reduce the pressure * * De creasing pressure (increasing volume) equilibrium shifts in the direction producing the larger number of moles of gas produces more pressure