Colloids: preparation and purification
Surface Chemistry and Colloids · Chemistry
Molecule viewer
Interactive 3DBall-and-stick models with true bond angles — switch molecule to compare shapes.
Controls
Drag the sliders or type a value — the simulation updates live.
Study notes
Make a gold sol by reduction: how would you prepare and purify it? Step 1: Reduce dilute HAuCl₄ with formaldehyde → ruby-red gold sol (condensation). Step 2: The sol contains K⁺, Cl⁻ impurities — these cause coagulation. Step 3: Dialyse: sol in a parchment bag in running water — ions diffuse out, gold stays. Step 4: Electrodialysis speeds it with an electric field. Pure sol: stable for months; impure: coagulates in days.