Where does this tube go?
 

Noticed that this was unplugged today, but couldn't figure out where it connects. It passes through the passenger strut area next to a condenser pipe.
Battery vent maybe?
Attachment 19344Attachment 19345

Yes, its the battery vent.

If the battery doesn't require a vent tube, then simply tie wrap it back out of the way.

There should be a small hole on the end of the battery near the top.

Some of the newer batteries have the vent hole in the middle back area where the decal of the car is. Your tube has the elbow in it indicating it was connected there at one time. If the opening is on the side it would not have the elbow.