[JLA]

Would the rate of a precipitation reaction between potassium iodide and lead (II) nitrate solutions be increased by a catalyst?  I sort of think not, as they are nearly instantaneous anyway and not subject to the orientation of collisions that covalent compounds would be. 

[discodermolide]

Would the rate of a precipitation reaction between potassium iodide and lead (II) nitrate solutions be increased by a catalyst?  I sort of think not, as they are nearly instantaneous anyway and not subject to the orientation of collisions that covalent compounds would be. 

I would imagine that the rate of precipitation depends upon the solubility product of the particular compound. Therefore, I do not think that a catalyst will affect this. At least I can't think of one.

[JLA]

Thanks!  Couldn't seem to find any info on the internet one way or the other ... all too generalised or way over my head!

[Darren]

Im guessing that precipitation reactions dont have catalysts to speed up the reaction because precipitation is between two aqueous solutions containing certain ions that form a solid when the concentration is high enough. So this depends on how much or how easily the solutions mix. The more you shake the mixture or stir it, the faster it happens as there is a greater chance for the ions to come together to form the ppt. And there wouldnt be a need for catalysts, either homogeneous or heterogeneous catalysts because they will just cause the solution to have a greater disorder or a greater number of varying substances, resulting in a lower chance for the specific ions to meet to form the ppt. And in the case of a heterogeneous catalyst, there is no need for it because that kind of catalyst speeds up reactions by allowing the reactants to 'stick' to their solid surface so that there is a greater surface area for the reactants to meet and react, speeding up the reaction. This is not required for precipitation reactions since the original solutions are in the aqueous state and can already mix well enough without a solid catalyst interferring with the solution.