Question:medium

Calculate osmotic pressure of 0.1 M aqueous solution of an electrolyte at 300 K if van't Hoff factor is 1.125. [R = 0.0821 atmdm$^3$ K$^{-1}$ mol$^{-1}$]

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The value of $RT$ at 300 K (with $R=0.0821$) is approximately 24.63.
Updated On: May 14, 2026
  • 2.15 atm
  • 2.41 atm
  • 2.77 atm
  • 3.25 atm
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The Correct Option is C

Solution and Explanation

Step 1: Understanding the Question:
We need to calculate the osmotic pressure ($\pi$) for an electrolyte solution using the van't Hoff factor ($i$).
Step 2: Key Formula or Approach:
The formula for osmotic pressure is:
\[ \pi = iCRT \] where $i$ is the van't Hoff factor, $C$ is molarity, $R$ is the gas constant, and $T$ is temperature in Kelvin.
Step 3: Detailed Explanation:
Given:
$i = 1.125$
$C = 0.1$ M
$T = 300$ K
$R = 0.0821$ atm$\cdot$L/(mol$\cdot$K)
\[ \pi = 1.125 \times 0.1 \times 0.0821 \times 300 \] \[ \pi = 1.125 \times 0.1 \times 24.63 \] \[ \pi = 0.1125 \times 24.63 \] \[ \pi \approx 2.770875\text{ atm} \] Step 4: Final Answer:
The osmotic pressure is approximately 2.77 atm.
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