Fresh water is to be extracted from brackish water at 15oC with a salinity of 0.1% (by

Question:

Fresh water is to be extracted from brackish water at 15oC with a salinity of 0.1% (by mass). Determine
(a) The minimum work required to separate 1 kg of brackish water completely into pure water and pure salts, and
(b) The minimum work required to obtain 1 kg of fresh water.