Experimental Procedure for Calculating Ksp of PbCl2 at Lab Temperature

[humaders99]

What would be an experimental procedure to determine Ksp of PbCl2 at lab temp, I think 22-25 degrees (the reaction being PbCl2 (s) ---> Pb + 2 CL). I am thinking that you'd take random amounts of Pb and Cl and wait for it to reach equilibrium and then somehow figure out how much of each chemical there is and then solve for Ksp (using concentrations of course)

 

[humaders99]

the thing with my little procedure is that it doesn't seem right, it seems like I am missing something important, or what i think the procedure should be doesn't make any sense :S

 

[chaoseverlasting]

I guess you could take Pb(OAc)2 soln and add HCl to slowly and see how many drops you need to get a ppt.

 

[chemisttree]

the thing with my little procedure is that it doesn't seem right, it seems like I am missing something important, or what i think the procedure should be doesn't make any sense :S

Adding chloride as a neutral salt is more correct since some sparingly soluble chlorides are more soluble in acidic solution. Try an experiment that has you adding NaCl to a solution of a soluble lead salt (PbOAc has been mentioned) a little at a time until a ppt forms. You will need to accurately determine the Cl- and Pb+2 of the solution at the various concentrations of added Cl-. There are gravimetric methods and more sophisticated methods for this such as ICP/MS or ICP. The concentration of these two species should be plotted and their product determined (Ksp) at each concentration.

 

[Borek]

IIRC PbCl2 solubility is high enough to do the expreiment other way around - start with pure PbCl2, let it saturate water, then take known volume of the water, dry it and weight the residue.