Synthesis

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Diffusion

An initial sample of two kinds of atoms is separated by an abrupt interface and contains a large concentration of vacancies. The random motion of the vacancies facilitates interdiffusion of the two layers. The right side shows a graph of the distribution of the two kinds of atoms. The motion of the vacancies is shown for the first 10% of each time period. (Companion Figure 10.1)

Lead iodide

Solid potassium iodide is added to solid lead nitrate. The mixture is stirred but little reaction is observed. Upon addition of water, the yellow product lead iodide immediately appears. (Companion Demonstration 10.2)

NiAl

A pressed bar containing equal moles of nickel and aluminum is attracted to a magnet (nickel is ferromagnetic). An exothermic reaction is initiated using a torch and the reaction front is seen to proceed down the bar. The nickel-aluminum alloy product is not attracted to the magnet. (Companion Demonstration 10.1)

Sol-gel rod

Silica Gel prepared by Sol-Gel synthesis in a test tube. (Companion Experiment 15)

Sol-gel shards

Silica Gel prepared by Sol-Gel synthesis in a petri dish. (Companion Experiment 15)

5 m fiber optic

Visible laser light is directed into a five meter long fiber optic and exits at the other end of the fiber optic.