I really don't understand equilibrium constants: they seem to change nonstop! Can someone clarify the definition of equilibrium constants and give me examples of them?
Also, I looked in my textbook and the explanation for heterogeneous equilibrium used an example of decomposing calcium carbonate.
$$\ce{CaCO3 (s) <=> CaO(s) + CO2(g)}$$
The textbook continued to explain that $K^{'}_{c} = \frac{[\text{CaO}][\text{CO}_{2}]}{[\text{CaCO}_3]}$
There is my first obstacle: What is the meaning of $K^{'}$ (I don't think they're talking about the reverse process equilibrium constant)? And the next part to me is even stranger...
I do get that the concentration of the two solids are basically constants, so we can treat those parts as constants.
But why would you do $K^{'} \times \frac{[\text{CaCO}_{3}]}{[\text{CaO}]}$, which equals $K$, according to the textbook, the actual equilibrium constant of this reaction?