Molten iron drops from the pots into a dish of sand. Explain buffer solutions as the color change slows. One liquid is added dropwise to another, forms a precipitate. Can be done with precipitates of different colors. Views nicely on the overhead projector using large well plates, but the color of the precipatates doesn't project.
Large flasks show colored precipatates well for large lecture halls.
Ionic vs. Covalent Bonding as Measured by Electrical Conductivity Procedure Check solutions and solids for conductivity using an apparatus that includes an incandescent lamp and an inert gas lamp in the circuit. Salts, sugars, weak and strong acids and bases all make good materials to check. When barium hydroxide solution is titrated with sulfuric acid, barium sulfate precipatates, and the lightbulb dims and then goes out. This demonstration, generally used in the organic chemistry courses, associates shapes of molecules with odors. Two solutions mix together to produce a fluorescent yellow glow that can be seen when the room lights are off.