Question

why will Na2CO3 + AgNO3 create a percipitate? I thought that one of the compounds has to be insoluble for it to form a percipitate?
but according to the solubility rules they both are soluble

Answer 1

It does and it is. You're not talking about JUST the solubility of Na2CO3 and AgNO3. When the two solutions are mixed they can interact to form NaNO3 (which is soluble) and Ag2CO3 (which is insoluble). All it takes is one insoluble material.

Answer 2

oh so even if the compound is soluble as long as it has a insoluble element(or ion) in either compounds it creates a percipitate 100% of the time?

Answer 3

oh or do you have to write out the products as if every equation produced something and if it produces an insoluble then that is the percipitate?

Answer 4

also do all strong acids and bases split?

Answer 5

I think you understand but I need to correct a slight misstatement. It isn't the element or ion that is insoluble; as you can see Ag^+ is soluble when in combination with some anions (AgNO3 etc) and CO3^2- is soluble with many cations (Na2CO3, K2CO3, etc). It's the combination of anion and cation that makes it insoluble. Ag2CO3 is always insoluble (unless the pH is too low of course). Here is a simplified set of solubility rules.
http://www.files.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html

And yes, Ag2CO3 is what causes the reaction to go essentially to completion. (formation of ppt is 1, formation of gas is 2, formation of slightly ionized substance is 3).

On the subject of strong acids and strong bases, remember this.
BY DEFINITION, a strong (or strong base) ionize 100%.