The Scorpion whip says:
http://www.d20pfsrd.com/equipment—final/weapons/weapon-descriptions/whip-scorpion
This whip has a series of razorsharp blades and fangs inset along its tip.
Benefit: It deals lethal damage, even to creatures with armor bonuses. If you are proficient with whips, you can use a scorpion whip as a whip.
Weapon Feature(s): performance (plus disarm, reach, and trip if you are proficient with whip.)
This seems very unclear though.
Does it have 15' reach?
Does it threaten? (At 5'? At 10'? At 15'?)
Does it do nonlethal damage if used at 15'?
I've found quite a bit of discussion online but mostly people arguing, nothing definitive.
Best Answer
There are two Scorpion Whips. The UC whip is not longer legal in PFS. Instead they use the AA whip. See this reddit post for the full explanation. I have put the relevant bits below. Technically the UC whip is the later printed item and thus supersedes the AA whip, but it is a horrible mess of confusion. I recommend you follow the PFS lead on this and stay the hell away from it.
Since Jacob James's posts talk about the Scorpion Whip from Ultimate Combat (and I'm not touching on the UC whip) his clarifications are not relevant to my answer.
Additional Resources Page
And thus the rules are as follows:
and S K Reynolds clarifies
Which means that the reach is 15 ft and it does not threaten.