Question

What is the minimum pressure in kPa that must be applied at 25 °C to obtain pure water by reverse osmosis from water that is 0.227 M in sodium chloride and 0.078 M in magnesium sulfate? Assume complete dissociation for electrolytes.

Answer 1

This is an application of osmotic pressure which is one of the colligative properties of substances. The formula of osmotic pressure is expressed as P = MRT where M is molarity , R is the gas constant and T is temperature. When M is equal to a total of 0.305 M and T is equal to 298 K , P should be equal to 7.46 atm