Question

$0.6MKCl$ and $0.07MMgC{l}_2$ solution are separated by semi-permeable membrane in a container. For this system, choose the correct answer:

• A. There is no movement of any solution across the membrane
• B. Osmotic pressure of $0.6MKCl$ is lower than the osmotic pressure of $MgC{l}_2$
  (assume complete dissociation)
  
• C. Water flows from $MgC{l}_2$ solution towards $KCl$ solution
• D. Water flows from $KCl$ solution towards $MgC{l}_2$ solution

Answer 1

The correct option is C Water flows from $MgC{l}_2$ solution towards $KCl$ solution

Osmotic pressure is the spontaneous movement of water across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration.

$\pi v=iCRT...\left(1\right)$
For $KCl,i=2andMgC{l}_2,i=3$
Given

$C_{KCl}=0.6M$
$C_{MgC{l}_2}=0.07M$
Put all values in equation $\left(1\right)$, we get

$\pi v_{KCl}=2\times 0.6\times RT=1.2RT$
$\pi v_{MgC{l}_2}=3\times 0.07\times RT=0.21RT$
It is clear that,

$\pi v_{KCl}>\pi v_{MgC{l}_2}$
So, water flows from $MgC{l}_2$ solution towards $KCl$ solution.