Question

Determine the amount of $CaC{l}_2$ dissolve in 2.5 L of water such that its osmotic pressure is 0.75 atm at ${27}^{0}C$. Assuming the degree of dissociation of $CaC{l}_2$ is 75%.

• A. 3.38 gm
• B. 5.27 gm
• C. 4.25 gm
• D. 52.7 gm

Answer 1

The correct option is A 3.38 gm

$i=1+\alpha (n-1)$

$i=1+\frac{3}{4}(3-1)$

$i=1+\frac{3}{2}=2.5$

Let $w$ be the amount of $CaC{l}_2$ dissolved.

$0.75=2.5\times \frac{w}{111}\times \frac{1}{2.5}\times 0.0821\times 300$

$w=3.38gm$