One important application of reverse osmosis is the desalination of seawater. To extract pure water from seawater using a semi-permeable membrane, pressure must be exerted on the seawater to exceed its osmotic pressure. Osmotic pressure is a colligative property, which depends only on the total molar concentration (M) of solutes: = MRT.
The following table lists the five most abundant salts in seawater and their amounts per cubic meter of seawater.
Salt Amount (kg / m3 seawater)
NaCl 28.014
MgCl2 3.812
MgSO4 1.752
CaSO4 1.283
K2SO4 0.816
Assuming that the other salts present in seawater are in negligible amounts, determine the pressure that must be exerted on seawater to desalinate it using reverse osmosis at 25oC.