HardChemistryHigh School (11–12)Solutions › Colligative Properties and the van 't Hoff FactorNumericalAP NEET

Well water has dissolved particles, ions and molecules together, at a total concentration of 0.25…

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Well water has dissolved particles, ions and molecules together, at a total concentration of $0.25\ \text{mol/L}$ at $298\ \text{K}$ . A reverse osmosis unit is to make fresh water from it. Find the least pressure that the pump must supply, in kPa. Then find the height of a column of fresh water that has this pressure at its base, in metres. Does a pump that supplies $1500\ \text{kPa}$ work?

Need a reminder? The key ideaShow

The osmotic pressure of a dilute solution is $\pi = CRT$ , with $C$ in mol/L and $T$ in kelvin. $R = 0.0821\ \text{L atm K}^{-1}\text{mol}^{-1}$ gives atm, and $R = 8.314\ \text{J K}^{-1}\text{mol}^{-1}$ gives kPa. Isotonic solutions have equal $\pi$ . A column of height $h$ of a liquid of density $\rho$ gives a pressure $\rho g h$ .

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

← All Problems

← A solution of glucose has 22.5 g in each litre…A solution has 4.35 g of potassium sulphate, K₂SO₄, of molar mass 174 g/mol, in 500 g of water… →

More onSolutions › Colligative Properties and the van 't Hoff Factor

Discussion (0)

Loading…