7. Write a mass action expression for the reaction between marble (CaCO2) and hydrochloric acid. Solution CaCO3(s) + 2HCl(aq) ------------> CaCl2(aq) + H2O(l) Rate of forward reaction = Kf[HCl]^2 Rate of reverse reaction = Kb[CaCl2] At equilibrium rate of forward reaction = rate of reverse reaction Kf[HCl]^2 = Kb[CaCl2] Kf/Kb = [CaCl2]/[HCl]^2 Kc = [CaCl2]/[HCl]^2 >>>answer .