93 CHAPTER-7 EQUILIBRIUM ? Equilibrium state-When rate of formation of a product in a process is in competition with rate of formation of reactants, the state is then named as “Equilibrium state” . ? Equilibrium in physical processes: solid ? liquid ? gas H2O(s )? H2O(l) ? H2O(vap) ? Law of chemical equilibrium: At a given temperature, the product ofconcentrations of the reaction productsraised to the respective stoichiometriccoefficient in the balanced chemicalequation divided by the product ofconcentrations of the reactants raised totheir individual stoichiometric coefficientshas a constant value. This is known asthe Equilibrium Law or Law of ChemicalEquilibrium. aA +bB?cC + dD Kc =[C]c [D]d/[A]a [B]b Chemical equation Equilibriumconstant aA + b B?c C + D K cC + d D?a A + b B K’c=(1/Kc) na A + nb B ?ncC + ndD K’?c= (Kcn) Concentrations or partial pressure of pure solids orliquids do notappear in the expression of the equilibriumconstant. In the reaction, Ag2O(s) + 2HNO3(aq) ?2AgNO3(aq) +H2O(l) ? If Qc >Kc, the reaction will proceed in thedirection of reactants (reverse reaction).If Qc 103; Kc is very high i.e. the reaction proceeds nearly to completion. ? If Kc