Question

For a dilute aqueous solution, density is $1.00 \,g \,cm ^{-3}$ and $g$ (acceleration due to gravity) is $10.0 \,ms ^{-2}$. Then, osmotic pressure set up at highest of $0.14\, m$ is

• A. 0.0138 atm
• B. $1.4 \times 10^{3} Pa$
• C. Both (a) and (b)
• D. None of these

Answer 1

Answer: (C)

At a column of height $h$,

Osmotic pressure $ \pi=\rho gh$

$=$ density $\times g \times h$

Density, $ \rho=1 \,g \,cm ^{-3} $

$\rho=\left(\frac{1}{1000} kg \right) 10^{6} m ^{-3} $

$\rho=10^{3} \,kg\, m ^{-3} $

$g =10.0 \,ms ^{-2} $

$h =0.14 \,m $

$\therefore \pi=10^{3} \times 10 \times 0.14 \,kg\, m ^{-1} s ^{-2}$

$=1.4 \times 10^{3} Pa $

$\pi=\frac{1.4 \times 10^{3} Pa }{1.013 \times 10^{5} \,Pa\, atm ^{-1}}$

$=0.0138 \,atm$

Thus, (a) and (b) both are correct.