[masteroc]

My general question is: what does Kc tell you about a reaction? I know that it is the equilibrium constant and that it is products over reactants, etc. But my question is more based on what does it mean? Again I know that it can mean that a reaction favors reactants or products...but what does this mean specifically as well.

Thanks

[Borek]

It describes equilibrium quantitatively - that means you can calculate equilibrium concentrations.

[Schrödinger]

The definition of Kc can probably help you understand better.
Usually (or always) Kc = Rate of forward reaction/rate of backward reaction.

The best part about Kc is that it is a link between thermodynamics and kinetics.