Question

Which of the following solutions have the lowest osmotic pressure and why ?
1)0 1M NaCl 2) 0 1 M glucose 3) 0 1 M BaCl2

Answer 1

Osmotic pressure is equal to (i×C×R×T)
Since C,R AND T are same for all we need to consider i here ,which is the vant Hoff factor.
For NaCl it is 2 (as it dissociates into 2 ions )
For glucose it is 1.
For BaCl2 It is 3.
Therfore glucose has the lowest osmotic pressure among all.

Answer 2

Answer:

Glucose will have the lowest osmotic pressure because it has the lowest i value.

Explanation:

Osmotic pressure π = i×C×R×T

Where,

i       =       Van't Hoff factor

C = molar concentration of solute

R = ideal gas constant

T = temperature in Kelvin

In the given problem, C,R and T are same for all three solutions. Therefore we have to consider only i.

In case of NaCl, it dissociates into 2 ions.

NaCl → $Na^{+} + Cl^{-}$

⇒i = 2

In case of glucose, it is a covalent compound and thus will not dissociate into its respective ions.

⇒i = 1

In case of $BaCl_{2}$, it dissociates into 3 ions.

$BaCl_{2}$ → $Ba^{2+} +2Cl^{-}$

⇒i = 3

Since glucose has the lowest i, it will have the lowest osmotic pressure.