# Adding more solid to a solid/gas equilibrium

$$\ce{CaCO3(s)<=> CO2(g) + CaO(s)}$$

In this equation, what happens if you increase the amount of one of the solids while there are existing quantities of everything else?

According to the calculation for the equilibrium constant, equilibrium is only dependent on the concentration of $\ce{CO2}$, so it technically should not change anything, right? However, if you decrease the pressure of the $\ce{CO2}$ enough, then shouldn't there be a point where the equilibrium constant can no longer be met because there aren't enough moles of $\ce{CO2}$?

Additionally, at this point, shouldn't adding more $\ce{CaCO3}$ change the point of equilibrium?

• Feb 11 '20 at 10:08

$\mathrm{K = constant}\times \ce{[CO2]}$
If one of the reactants ($\ce{CaCO3, CaO, CO2}$) is not present, there is no equilibrium.