By the time of the split, we'll have played 17 home games and 16 away matches.
That means the split will give us 2 more at home (most likely Hearts or whoever finishes 5th and against whoever finishes 6th) and 3 away (against Celtic, Hibs and Aberdeen).
The split is never perfect and in my opinion makes the league a bit of a laughing stock - I'd personally have a 10 team top tier and play 36 fixtures, with 2 home and away against each side. Expand the Championship and have 2 teams guaranteed to come up and go down, with a playoff for a third spot. The fixtures a split throws out will never be completely fair.