Question

Pour solutions $A,\,B,\,C,\,D$ has glucose $0.5\, M,\, NaCl\, 0.1\, M$, $BaCl _{2} 0.5\, M$ and $MgCl _{2} 0.1\, M$, then which of the following will have highest osmotic pressure?

• A. Glucose
• B. $ BaCl_{2}$
• C. $ MgCl_{2}$
• D. $ NaCl $

Answer 1

Answer: (B)

Molar concentration of glucose $=0.5\, M$ Molar
concentration of $NaCl =0.1\, M$
Molar concentration of $BaCl_{2}=0.5\, M$
and molar concentration of $MgCl_{2}=0.1\, M$
However as $NaCl,\, BaCl_{2}$ and $MgCl_{2}$ is an electrolyte.
One mole of $NaCl$ give two mole ions, therefore molar concentration of particles in the solution $=0.2\, M$
One mole of $BaC l_{2}$ give three mole ions,
therefore molar concentration of particles in the solution $=1.5\, M$.
and one mole of $MgCl _{2}$ give three mole ions,
therefore molar concentration of particles in solution $=0.3\, M$.
As, osmotic pressure is directly proportional to the number of particles in the solution,
hence, increasing order of osmotic pressure will be.
Glucose $< NaCl < MgCl _{2}< BaCl _{2}$