For which reaction will kp = kc? for which reaction will kp = kc? h2co3(s) ? h2o(l) + co2(g) 2 h2o(l) ? 2 h2(g) + o2(g) 2 hgo(s) ? hg(l) + o2(g) caco3(s) ? cao(s) + co2(g) c(s) + o2(g) ? co2(g)

Kp and Kc are both equilibrium constants however these do not mean the same things. Kp is an equilibrium constant based on the partial pressures of the substances in equilibrium while Kc is the equilibrium constant that is based on the concentrations of the substances in equilibrium. These two constants are related by the equation Kp = Kc (RT)^Δn. So, they can only be equal when Δn is zero. This happens when the number of total moles of the products is equal to the total number of moles of the reactants. Thus, the answers are the reactions:

 2 HgO(s) = Hg(l) + O2(g)
CaCO3(s) = CaO(s) + CO2(g)