Question

Which of the following would exert maximum osmotic pressure?

• A. Decinormal aluminium sulphate
• B. Decinormal barium chloride
• C. Decinormal sodium chloride
• D. A solution obtained by mixing equal volumes of and and filtering

Answer 1

Answer: (A)

Osmotic pressure is a colligative property, ie, depends upon the number of particles of solute. Thus, the solution in which solute gives maximum number of ions, exerts maximum osmotic pressure. Number of particles, [a] In decinormal aluminium sulphate,
$A{l}_2{(S{O}_4)}_3\to \underset{5particles}{\underbrace{2A{l}^{3+}+3S{O}_4^{2-}}}$
[b] In decinormar^barium chloride, $BaC{l}_2\to \underset{3particles}{\underbrace{B{a}^{2+}+2C{l}^{-}}}$
[c] In decinormal sodium chloride, $NaCl\to \underset{2particles}{\underbrace{N{a}^{+}+C{l}^{-}}}$
[d] When equal volumes of [b] and [c] are mixed, the concentration becomes half of present concentration. Thus, decinormal aluminium sulphate exerts maximum osmotic pressure.