Question

What is the correct order of osmotic pressure of $0.01M$ aqueous solution of
$\left(\right.1\left.\right)$ $Al_{2}\left(\right.SO_{4}\left(\left.\right)_{3}$
$\left(\right.2\left.\right)$ $K_{3}PO_{4}$
$\left(\right.3\left.\right)$ $BaCl_{2}$
$\left(\right.4\left.\right)$ Urea

• A. $\pi _{4}>\pi _{3}>\pi _{2}>\pi _{1}$
• B. $\pi _{1}>\pi _{2}>\pi _{3}>\pi _{4}$
• C. $\pi _{1}=\pi _{2}=\pi _{3}=\pi _{4}$
• D. $\pi _{2}>\pi _{4}>\pi _{1}>\pi _{3}$

Answer 1

Answer: (B)

At same molar concentration, the osmotic pressure will depend on van't Hoff factor 'i'.
$\pi =iCRT$
i.e., more the value of 'i' more will be the value of osmotic pressure.
Thus, osmotic pressure will lie in the sequence.
$\underset{A l_{2} \left(\right. S O_{4} \left(\left.\right)_{3}}{\left(\pi \right)_{1} \left(\right. i = 5 \left.\right)}>\underset{K_{3} P O_{4}}{\left(\pi \right)_{2} \left(\right. i = 4 \left.\right)}>\underset{B a C l_{2}}{\left(\pi \right)_{3} \left(\right. i = 3 \left.\right)}>\underset{U r e a}{\left(\pi \right)_{4} \left(\right. i = 1 \left.\right)}$