Changes in the microstructure of oil-in-water microemulsions were identified electrochemically by using ferrocene derivatives, methyl viologen, and ferricyanide as the electroactive probes. Microdroplets as well as the bicontinuous microstructure were detected. This was accomplished by determining diffusion coefficients of the probes. Use of probes of different hydrophobicity/hydrophilicity and charge made it possible to investigate different microenvironments of microemulsions including oil, water, and surfactant/cosurfactant interface. Electrochemical reversibility of the probes was affected by the structure and appeared to reflect the ease of mobility across interphases. Reaction potential (E1/2) of the probes depended on the composition of the microemulsion.

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The relationship between apparent diffusion coefficients, D', of electroactive probe and thc microstructure of an oil-in-water anionic microemulsion, sodium dodecyl sulfate (SDS)/dodecane/I-pentanol/0.1 M NaCI,, has been investigated. Three probes, ferroceiie (Fc), Fe(CN)i-and methyl viologen (MV2+) allowed the effect of ditrerent microstructure and interactions on the d-values to be investigated. The results indicate that the droplet as well as hicontinuous microemulsion structures can be identified and point to the effects of crossphase exchange, partitioning, and multiple binding on the D'-values.

The Molecular Model Game is used to review Lewis structures and VSEPR theory. In this game, teams of students compete to complete problems quickly. Variations with other types of problems involving stoichiometry or equilibria are also possible.

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