04-12-2018, 05:09 AM

I'm being asked to find the volume of a NH3 solution (0.1 M) to be added to 10 mL of a AgNO3 solution (0.1 M) to assure the 'complete formation of [Ag(NH3)2]+' . Both constants of formation are given: β1=103.3; β2=107.2

As far as I know, a complete complexation would mean that [Ag+]<10−5. I tried working it out with the common method of solving those kind of complex equilibria, but the equations I get seem pretty much impossible to solve because of the volume that I have to find, which gets incorporated in them.

Their solution is really weird, but much simpler; they invoke this mathematical condition, which makes the problem easily solvable:

[Ag(NH3)+2][Ag(NH3)+]>102

Starting from this, I can find [NH3] present in the solution, therefore the volume.

Where did it came from?

As far as I know, a complete complexation would mean that [Ag+]<10−5. I tried working it out with the common method of solving those kind of complex equilibria, but the equations I get seem pretty much impossible to solve because of the volume that I have to find, which gets incorporated in them.

Their solution is really weird, but much simpler; they invoke this mathematical condition, which makes the problem easily solvable:

[Ag(NH3)+2][Ag(NH3)+]>102

Starting from this, I can find [NH3] present in the solution, therefore the volume.

Where did it came from?