Phase 1: Grasping Colloidal Systems
Colloidal particles constitute heterogeneous mixtures where dispersed-phase particles measure between 1 nm and 1000 nm.
Their inherent electrical charge is crucial for stability, averting coagulation.
Phase 2: Charge Origin Mechanism
The electrical charge on colloidal particles predominantly results from ion adsorption from the surrounding solution.
When a colloidal particle interacts with a solution, selective adsorption of specific ions takes place.
Phase 3: Illustrative Charge Formation Scenarios
- In the preparation of AgI sol with excess KI, the colloidal particles adsorb \( I^- \) ions, resulting in a negative charge: \[ AgI + I^- \rightarrow {Negatively charged AgI colloid} \] - Conversely, if AgI sol is prepared with excess AgNO$_3$, the colloidal particles adsorb \( Ag^+ \) ions, acquiring a positive charge: \[ AgI + Ag^+ \rightarrow {Positively charged AgI colloid} \] Phase 4: Charge's Role in Colloidal Stability
- The electrostatic repulsion between colloidal particles bearing identical charges inhibits coagulation, maintaining dispersion. - Mixing colloids with opposing charges can lead to coagulation (precipitation).
Conclusion: Colloidal particle charge is an outcome of ion adsorption from the solution.