Because 500 or 1000 ml of 0.9 NS have the same concentration of NaCL relative to the water amount, I can make a 500 ml bag of NS in two ways: 1. Mix 4.5 gm of NaCl in 500 ml of free water, that will still give me 154 meq of Na + 154 meq of Cl = 308 meq. 2. Mix 9 gm of NaCl in 1000 ml of free water then split the 1000 ml bag into two halves 500 ml each. It will result in the same 154 meq of Na + 154 meq of Cl = 308 meq.