3 P4 + 5O2 W P4O10 K= [P4O10]/ [P4] [O2]5 Calculating equilibrium Constants Lets look at the equilibrium that describes waht happens when acetic acid dissociates in water. What do you think the expression for the reverse reaction lC + mDW jA + kB is? 4 Along the same lines, what is we have a multiplier for the entire equation i.e. N2 + 3H2 W2NH3 ; K=[NH3]2/[N2][H2]3 = 3.8×104 L2/mol2 (previous example) Suppose we want the equilibria expression of the reaction N2 + 3/2 H2 WNH3 instead?