The correct answer is option: 4. B < A < C < D.
Let us go through the detailed explanation step by step:
1. Formation of Colloidal Solution:
When a highly diluted solution of \(KI\) is added to \(AgNO_3\) solution, a precipitation reaction occurs, forming \(AgI\) as a colloidal solution.
\[ Ag^+_{(aq)} + I^-_{(aq)} \rightarrow AgI_{(colloidal)} \]
2. Charge of Colloidal Particles:
In this process, iodide ions (\(I^-\)) from \(KI\) react with silver ions (\(Ag^+\)) from \(AgNO_3\), resulting in the formation of \(AgI\) colloidal particles.
The excess \(Ag^+\) ions in the solution lead to a positive charge on the colloidal particles.
3. Coagulation of Colloidal Particles:
To coagulate the positively charged colloidal particles, an electrolyte with negatively charged ions (anions) is required.
The anions in the added electrolyte will neutralize the positive charges on the colloidal particles, leading to coagulation or precipitation.
4. Selection of Coagulating Electrolytes:
The ease of coagulation depends on the nature and charge of the anion in the added electrolyte.
Anions with higher negative charge are more effective in neutralizing and coagulating the positively charged colloidal particles.
5. Comparison of Anions in Options:
The given options include different anions in the electrolytes: \(Cl^-\), \(SO_4^{2-}\), \(PO_4^{3-}\), and \([Fe(CN)_6]^{4-}\).
Comparing their negative charges, we have \(Cl^- < SO_4^{2-} < PO_4^{3-} < [Fe(CN)_6]^{4-}\).
6. Order of Increasing Ease of Coagulation:
The order of increasing ease of coagulation is \(NaCl < BaSO_4 < Na_3PO_4 < K_4[Fe(CN)_6]\).
In summary, the positively charged colloidal solution formed by adding \(KI\) to \(AgNO_3\) can be coagulated by anions from different electrolytes. The order of increasing ease of coagulation is determined by the negative charge of the anions in the electrolytes. The explanation considers the charge interactions and the principles of colloid chemistry. |
