JEE Main 2014 · 19 Apr · Shift 1 · Chemistry Q38

← JEE Main 2014 · 19 Apr · Shift 1

ChemistrySingle correct+4 / -1Question 38 of 90

The observed osmotic pressure for a 0.10 M solution of $\ce{Fe(NH4)2(SO4)2}$ at 25°C is 10.8 atm. The expected and experimental (observed) values of Van't Hoff factor (i) will be respectively :

(R = 0.082 L atm k $^{-1}$ mol $^{-1}$ )

5 and 4.42

4 and 4.00

5 and 3.42

3 and 5.42

Answer and worked solution

Official answer: A

Mohr's salt gives $\ce{Fe^2+ + 2NH4+ + 2SO4^2-}$ : 5 ions, so the expected $i=5$ .
$i_{obs}=\frac\pi{CRT}=\frac{10.8}{0.10\times0.082\times298}\approx4.42.$

Topics:van't Hoff factor Colligative properties

← Previous question Next question →

JEE Main 2014 · 19 Apr · Shift 1, Chemistry question 38