soluble compound? HELP!?

Question

how is silver chloride is an insoluble compound when silver is insoluble, but chloride is soluble? does just one element have to be insoluble for the whole compound to be insoluble??!?

THANKS IN ADVANCE!

Answer 1

Sodium chloride is soluble.

Silver nitrate is soluble.

BUT silver chloride just happens to be insoluble.

So if solutions of sodium chloride and silver nitrate are mixed together, a white precipitate of insoluble silver chloride is produced.

See more information about solubility rules at

http://www.ausetute.com.au/solrules.html

Answer 2

Well, AgCl(s) is soluble enough if you put it into a solution of potassium cyanide or ammonia, but I presume that you are referring to solubility in just plain water or, preferably, slightly acidified water.

The key here to remember is that the salt's solubility is dependent upon the interaction of the metal and the halide, and perhaps more importantly the actual concentration of the silver and the chloride in the solution.

The solubility product for silver chloride is 1.8 x 10^-10. Remember that the formula for dealing with the solubility of silver chloride is roughly:

Ksp = [Ag+(aq)][Cl-(aq)]

If the product of the actual concentrations of the ions present in the solution for the silver ions and the chloride ions have a value less than the solubility product, you don't get a precipitate.

BUT, when the product of the concentrations exceed this value, you do get a precipitate. It just comes down to simply multiplying the concentrations of the two sets of ions.

Answer 3

Silver compounds are soluble. Consider AgNO3. Chlorides are soluble, as you point out. It's just that Ag+ and Cl- combine to form AgCl, one of the most water-insoluble compounds known. It's the same with Ba(NO3)2, Na2SO4, and BaSO4. One of the absolutely most insoluble compounds known is HgS, and yet...