Question

Assuming each salt to be 90% dissociated, which of the following will have highest boiling point?

• A. Decimolar $A{l}_2(S{O}_4{)}_3$
• B. Decimolar $BaC{l}_2$
• C. Decimolar $N{a}_{2}S{O}_4$
• D. A solution obtained by mixing equal volumes of (B) and (C)

Answer 1

Answer: (A)

Decimolar $A{l}_2(S{O}_4{)}_3$

One molecule of $A{l}_2(S{O}_4{)}_3$ on dissociation gives 5 particles.

One molecule of $BaC{l}_2$ on dissociation gives 3 particles.

One molecule of $N{a}_{2}S{O}_4$ on dissociation gives 3 particles.

The concentration of three solutions is same. The degree of dissociation is also same.

The boiling point will be highest for $A{l}_2(S{O}_4{)}_3$ as it gives the maximum number of particles on ionization.

Option D is not correct because the number of particles obtained per molecule will be 3 which is lower than 5.