The Physician has ordered a 4g loading dose of Magnesium sulfate IV to be given over a 30 minutes period. The IV solution has 40g of Mag Sulf in 1000ml.The nurse should infuse.......mls of Mag Sulf at a rate of .........ml/hr First you find the equivalent of 4g in ml If 40g = 1000 then 4g = 4/40 *1000 the answer is 100ml. That means you are supposed to give 100ml in 30 minutes. For an hour, it will be 200ml/hr. So the nurse will infuse 100ml of MgSo4 at a rate of 200ml/hr