Question

What amount of $CaCl_{2}$ ($i = 2.47$) is dissolved in 2 litres of water so that its osmotic pressure is $0.5$atmat $27ºC$?

• A. $3.42g$
• B. $9.24g$
• C. $2.834g$
• D. $1.820g$

Answer 1

Answer: (D)

$1.820g$

Answer 2

$\pi = CRT = i\frac{n}{V}RT$

$n = \frac{\pi \times V}{i \times R \times T} = \frac{0.5 \times 2}{2.47 \times 0.0821 \times 300} = 0.0164mol$Amount of $CaCl_{2} = n \times M = 0.0164 \times 111 = 1.820g$