Question

why NaCl is more soluble then AgCl ?

Answer 1

Most compounds can be broadly classified into 2 groups.

Polar and Non-polar

1. Polar compounds:- these compounds show something called a charge separation where in one particular ion possesses a certain charge while another ion possesses the opposite charge. NaCl is made up of Na+ and Cl- ions which combine to form NaCl, and so therefore show a clear separation of positive and negative charge within the compound( charge separation). The same goes for H2O (water) which is made up of H+ and OH- ions again with a clear charge separation.
2. Non polar compunds:- these compounds don’t show a charge separation large enough to actually make a difference in their behaviour. AgCl is an example of this. Although Ag is more positive compared to Cl due to the nature of their bonding this difference isn’t large enough to really make a difference.

In solution chemistry we have a rule “like dissolves like”, which simply means that a polar compound(like NaCl) is soluble in a polar solvent(like water) and a non polar compound(like AgCl) is soluble in a non polar solvent(like CCl4). Apolar compound however doesn’t dissolve in a non polar solvent and a non polar compound doesn’t dissolve in a polar solvent.

There are special cases where this doesn’t apply but in this case and most cases out there it does and will.