1 Volt and potential difference?

[p.tryon]

How far do you need to separate two opposite 1C charges inorder for the potential difference to be 1v?

 

[Born2bwire]

It's completely arbitrary as the potential would vary with distance from the charges. When you say potential difference though, what is your reference potential then? Is it assuming 0 V at infinity? If so then the potential that results from a point charge is trivial:

\Phi = \frac{1}{4\pi\epsilon_0}\frac{q}{r}