Question

17. A 0.100 m solution of which one of the following solutes will have the lowest

vapour pressure?

A. KClO4
B. Ca(ClO4)2

C. Na3PO4

D. C6H12O6

E. NaCl

Answer 1

Solution

KClO_{4 =} 1K⁺ and 1ClO₄: i=2

2$\times 0.1= 0.2$

Ca(Cl0₄)= 1Ca²⁺ and 2ClO₄^- : i=3

$3\times 0.1= 0.3$

Al(ClO₄)₃= 1Al³⁺ and 3ClO₄^-: i=4

$4\times 0.1= 0.4$

Sucrose i= 1

$1\times0.1= 0.1$

1Na⁺ and 1Cl^- :i=2

$2\times0.1 =0.2$

Therefore Al(ClO₄)₃ has the lowest vapour pressure of 0.4