Osmotic pressure of 1 mol of ideal solute relative to pure water is:

1 mol of an ideal solute dissolved in 1000g of water (a 1m or molal solution) at 1 atm pressure yield a solution whose osmotic pressure relative to pure water is 22.4atm (250C). Ref: Principles of Medical Physiology by Sabyasachi Sircar, 2008/2-22