Question

A $0.010g$ sample of $Cr{\left({NH}_3\right)}_4\left({SO}_4\right)Cl$ is dissolved in $25.0mL$ of water and the osmotic pressure of the solution is $59.1\text{torr}$ at ${25}^{\circ }C.$ How many moles of ions are produced per mole of compound?

• A. $1$
• B. $4$
• C. $2$
• D. $3$

Answer 1

Answer: (C)

$2$

solution:

$\pi =iCRT=\frac{59.1}{760}atm$

$c=molarity=\frac{no.ofmoles}{volume}\times 1000$

$c=$ (weight of given solute / (mol. mass x 25) ) x 1000

$\pi =\frac{59.1}{760}=i\times \frac{0.010\times 1000}{251.5\times 25}\times 0.0821\times 298$

$i=\frac{59.1\times 251.5\times 25}{0.010\times 1000\times 0.0821\times 298}$

$i=2$

Hence the correct option: C