This is a one molar solution of sodium bicarbonate. That is to say, one litre of this stuff contains one mole (84g ) of sodium bicarbonate.
Given that in solution it dissociates into two particles, the osmolality is actually 2 Osm/kg. Yes, 2000 mOsm/Kg. This is another solution which is unkind to peripheral veins. The 100ml bottles of 8.4% bicarbonate contain 100mmol.