Equilibrium

[idkididk]

---

Members don't see this ad.

http://i.imgur.com/FlifzHS.png

Why will adding ammonia NOT drive the reaction to the right? I understand that the equilibrium constant is only equal to the concentration of NH4+ times concentration of NH2-, and that the equilibrium constant does not depend on liquids or solids.

I'm thinking of an analogous reaction where I'm dissolving some solid. The equilibrium constant does not depend on the solid, but if my solution isn't saturated, wouldn't I drive the equation to the right by adding more solid?

 

[JMMTB]

Adding NH3 does cause more NH4+ and NH2- to form, but their concentrations are still the same so the Keq is fixed. Think if for every 10 NH3 molecules 2 dissociated. If we add 5 more NH3 molecules, 1 would dissociate, but our ratio (concentration) is still 1 dissociated/5 NH3 molecules.

Just like with distilled water adding more does not change the pH which is a result of the OH and H concentrations.

As for solids, like you said adding solid to a unsaturated solution will cause more to dissolve. This is because our Q value would be less than our Keq.