Question

Which of the following order is true about the flocculation power in the coagulation of negative solution?

• A. ${\mathrm{Al}}^{3+}>{\mathrm{Ba}}^{2+}>{\mathrm{Na}}^{+}$
• B. ${\mathrm{Ba}}^{2+}>{\mathrm{Na}}^{+}>{\mathrm{Al}}^{3+}$
• C. ${\mathrm{Na}}^{+}>{\mathrm{Al}}^{3+}>{\mathrm{Na}}^{+}$
• D. ${\mathrm{Na}}^{+}>{\mathrm{Al}}^{3+}>{\mathrm{Ba}}^{2+}$

Answer 1

The correct option is A

${\mathrm{Al}}^{3+}>{\mathrm{Ba}}^{2+}>{\mathrm{Na}}^{+}$

Explanation for the correct option:

A) ${\mathrm{Al}}^{3+}>{\mathrm{Ba}}^{2+}>{\mathrm{Na}}^{+}$

• A positive ion is necessary for flocculation with a negative sol.
• The ability of the additional flocculating ion to precipitate increases with valence. The flocculation power of a cation decreases with a decrease in the cation's valence.
• So the flocculating power will be more for the cation that carries a more positive charge.
• Hence, ${\mathrm{Al}}^{3+}$ comes first, then comes ${\text{Ba}}^{2+}$ and then last ${\text{Na}}^{+}$.

Explanation for the correct options:

The flocculation power in the coagulation of the negative solution follows this trend ${\mathrm{Al}}^{3+}>{\mathrm{Ba}}^{2+}>{\mathrm{Na}}^{+}$. Thus, options B, C, and D are incorrect.

Hence, option (A) is correct i.e. ${\mathrm{Al}}^{3+}>{\mathrm{Ba}}^{2+}>{\mathrm{Na}}^{+}$