Liquids, Solids, and Materials

 

Ammonia Fountain – Show the solubility of NH3 (g) in H2O due to hydrogen-bonding.

Boiling Water at Room Temperature – Show water boiling at room temperature in a beaker in an evacuated bell jar, then put your hand in the water after boiling to convince students of its low temperature.

Combustion of Ethanol Vapors – Allow a small amount of ethanol to vaporize in a large carboy, pour out the excess liquid, and hold a lighted splint to the mouth of the container – the impressive reaction also demonstrates the flammability of organic vapors.

Diffraction of Light  – Use a laser pointer and a slide containing eight different arrays of dots to simulate x-ray diffraction experiments.

Disappearing Styrofoam Cup – Make a styrofoam (expanded polystyrene) cup disappear by placing it in a dish of acetone.

Dry Ice Sublimation – Make the sublimation of dry ice “visible” by dropping a piece of dry ice in a beaker of water. (Optional: place a piece of dry ice in a glove, tie it off, and allow the dry ice to sublime, inflating the glove.)

Effect of Pressure on the Melting Point of Ice – Hang a wire weighted at both ends over a cylinder of ice; eventually the wire passes through the ice and the weights fall, leaving the ice intact. The ice below the wire melts due to pressure from the weights, and the water above the wire refreezes as the pressure is relieved.

Ether Fire – Demonstrate the high vapor pressure of diethyl ether by allowing the vapor to flow from a can down a trough to a candle, resulting in a vapor flashback fire.

Gooyuck-Oobleck – Pass around bowls of a cornstarch-water mixture; the properties of this non-Newtonian fluid challenge our traditional definitions of liquid and solid (and is awesome).

Meissner Effect – Demonstrate the levitation of a tiny magnet over a superconductor.

Negative Volume of Mixing – Mix ethanol and colored water in a graduated cylinder to demonstrate their miscibility and negative volume of mixing due to hydrogen bonding.

Nylon 6-10 – Demonstrate the polymerization of hexamethylenediamine with sebacoyl chloride to produce the polyamide Nylon 6-10.

Polarity and Geometry – Show the dependence of dipole-dipole forces on geometry by contrasting the effect of a charged rod on streams of H2O and “CCl4” (actually hexane) flowing from burets.

Polarity and Solubility –  Add acetone to a saturated solution of CuSO4(aq) causing CuSO4(s) to crystallize out – the solubility of CuSO4 decreases as the polarity of the solvent is decreased

Slime! – Make a cross-linked gel by mixing solutions of polyvinyl alcohol and borax; use this demo to relate concepts such as polymers and hydrogen-bonding to a commercial product students are familiar with.

Vapor Pressure Evaporation – Show the effect of intermolecular forces on vapor pressure by letting students make streaks of water, methanol, and acetone on the blackboard and then observing the relative rates of evaporation.

Viscosities of Liquids – Compare the viscosity of various liquids on the overhead projector and relate the differences to strength of attractive forces.