Which one of the following electrolytes has the same value of van't Hoff's factor (i) as that of Al2(SO4)3 (if all are 100% ionised) ?
Al(NO3)3
K4[Fe(CN)6]
K2SO4
K3[Fe(CN)6]
As we learned in concept:
Vant Hoff factor for dissociation -
Where
is the no. of dissociated particles
degree of association
- wherein
Let's check Van't Haff factor for each option.
Al(No3)3 -> Al3+ + 3(No3)-, i = 4
K4[ Fe (CN)6] -> 4K+ + [ Fe (CN)6]4-, i = 5
K2So4 -> 2K+ + So42-, i=3
K4[Fe (CN)6] -> 3K+ + [Fe (CN)6]3-, i = 4
Al2(So4)3 -> 2Al3+ + 3 So42-, i = 5
Clearly, answer is K4[Fe(CN)6]
Option 1)
Al(NO3)3
this is the incorrect option
Option 2)
K4[Fe(CN)6]
this is the correct option
Option 3)
K2SO4
this is the incorrect option
Option 4)
K3[Fe(CN)6]
this is the incorrect option