Question

Solution A has ${\Psi }_S=–30$ bars and ${\Psi }_P=5$ bars. Solution B has ${\Psi }_S=–10$ bar and ${\Psi }_P=0$ atm. The two are separated by semipermeable membrane. Flow of water will be

• A. B to A
• B. A to B
• C. Equal in both directions
• D. No flow of water

Answer 1

The correct option is A

B to A

Water flows from a system with higher water potential to a system with lower water potential.

Solution A has ${\Psi }_S$ = – 30 and ${\Psi }_P$ = 5 bars

Solution B has ${\Psi }_S$ = – 10 and ${\Psi }_P$ = 0

${\Psi }_W={\Psi }_S+{\Psi }_P$ So, for solution A ${\Psi }_w$ = – 30 + 5 = – 25

For solution B ${\Psi }_w$ = – 10 + 0 = – 10

So, flow of water is from ‘B’ to ‘A’ i.e., – 10 to – 25