BR test 1 physical sciences q 8

[2010premed]

Which salt is the MOST difficult one from which to extract silver cation from its ionic lattice into solution?

• AgBr</SPAN>
• Ag2CO3

</SPAN>
A: A

First of all, I don’t understand how this question is asking for the LEASt soluble salt, I thought it was asking for the most soluble salt, since then it would be hard to extract the AG from, b/c it’s mixed in the solution. Second of all, the molar solubility value for AgBr is given as 9.6 x 10^-7. Why isn’t Ag2CO3 even less soluble, b/c I thought that according the solubility rules CO3 salts are not soluble?? (The value for Ag2CO3 is not given in the table)

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[fizzgig]

if it's difficult to break out of its lattice (as it exists as a solid), it doesn't want to break down into ions. more difficult to break out of lattice = less soluble.

i dont know about the second part. dunno what other info there is. but keep in mind for 2 cpds with very similar Ksp values, the one with 3 ions is going to be more soluble. that may be part of it...

 

[2010premed]

Thanks a lot