Question

Which of 0.1 M urea and 0.1 M NaCl will have more osmotic pressure? Explain with reason.

Hint:

Electrolytes give higher colligative properties due to dissociation (\(i>1\)).

Answer 1

Step 1: Recall osmotic pressure formula.
\[ \pi = i C R T \] where \(i\) = van’t Hoff factor.
Step 2: For urea.
Urea is non-electrolyte → \(i=1\).
Step 3: For NaCl.
NaCl dissociates completely → \(i=2\). So effective concentration doubles.
Step 4: Conclusion.
Osmotic pressure of NaCl solution is higher than that of urea.