On 01/03/2010, at 13.55, Boaz Shaanan wrote:
As for equilibrium constants, I'm somewhat puzzled by your remark on their lack of units (I'm a chemist by the way). Is the equilibrium constant (or dissociation constant) of the reaction A+B<->AB identical to that of the reaction: A+2B <--> AB2 ? I didn't think so. I could of course misunderstand your statement, so please correct me.
The equilibrium constant is defined as a ratio of the products of the chemical activities on the right and left sides of the equilibrium, and chemical activities themselves are dimensionless. In practical work, we use concentrations, which do have dimensions, but are multiplied by an activity factor which is usually ignored because it is very close to 1. For this reason, it appears that K has a unit, but it's only nominal.
Cheers, Morten
