General chemistry ii part 2. the equilibrium constant. k: every equilibrium reaction has an equilibrium constant k, that gives us information about how far in the forwards direction a reaction will proceed until it reaches equilibrium. k can be calculated using the ratio of the concentrations of species present at equilibrium, raised to the power of the stoichiometric coefficients. for our generic equilibrium, az(9) + 2b9) zab9), the equilibrium constant, k =[ab]/([a2][b]). the numerical value of k is a constant for a given reaction at a fixed temperature. when you manipulate the reaction, you also have to manipulate the value of k. you should know the following 3 rules pertaining to this: • when you reverse a reaction the value of k for the reverse reaction, kry1/k. when you multiply the stoichiometric coefficients in a reaction by n. know (old) • when you add 2 reactions, the value of k for the new reaction, knew = (komi)(kouz) 2. let's consider the reaction 4no (9) + 6h20 (1) 4nh3(g) +502 (9) (k) a) write an expression for the equilibrium constant (1) b) now write expressions for the following equilibrium constants in terms of k. this means that your final answer should have ki in it. 2no(g) + 3h20 (1) 2nh3(g) + 2.50z (6) (k2) 2nh3(g) +2.502 (9) 2no(g) + 3h20 (1) (k3)