Question

At \(300\,K\), \(x\) moles of \(CaCl_2\) \((i=2.5;\ \text{molar mass}=111\,g\,mol^{-1})\) is dissolved in \(2.5\,L\) of water. The osmotic pressure of the resultant solution is \(0.75\,atm\). What is \(\Delta T_b\) of the solution? \[ (\text{density of water}=1\,g\,mL^{-1},\; K_b=0.52\,K\,kg\,mol^{-1},\; R=0.08\,L\,atm\,mol^{-1}K^{-1}) \]

• A. \(0.016\,K\)
• B. \(0.032\,K\)
• C. \(0.048\,K\)
• D. \(0.064\,K\)

Hint:

Use osmotic pressure first to find concentration: \[ \pi=iCRT \] Then use \[ \Delta T_b=iK_bm. \] For dilute aqueous solutions, \[ 1\,L\ \text{water}\approx1\,kg\ \text{water} \] when density is \(1\,g\,mL^{-1}\).

Answer 1

The Correct Option is A