Suppose that one wishes to use reverse osmosis to reduce the salt content of brackish water containing 0.22 M total salt concentration to a value of 0.01 M, thus render- ing it usable for human consumption. What is the mini- mum pressure that needs to be applied in the permeators (Figure 18.20) to achieve this goal, assuming that the oper- ation occurs at 298 K? (Hint: Refer to Section 13.5.)

Video transcript

Hi everyone here we have a question telling us that domestic reverse osmosis systems are becoming more and more common in cities where access to clean drinking water is limited. Assume that the feed water for such a system has a salt concentration of 0.345 polarity. What is the minimum pressure that needs to be applied to the membrane of the system to reduce the salt concentration to 0.113 molar itty at 28.0°C. So our change in polarity Equals 0.345 Polarity -0.113 Molar itty Equals 0.232 More Clarity. So our temperature Needs to be in Kelvin. So that's going to equal 28.0°C plus 273. Equals 301 . Kelvin. Our osmotic pressure equals are changing polarity times are constant times our temperature in kelvin. So our osmotic pressure Equals 0.232 More clarity Times. 206 l times, atmospheres divided by moles times, kelvin Times .15 Kelvin. And that gives us osmotic pressure Equalling 5.73 Atmospheres. And that is our final answer. Thank you for watching. Bye