The concept of "like dissolves like" is explored using a solvent extraction demonstration appropriate for first-year chemistry students. Equal volumes of aqueous methyl red and blue copper(II) sulfate form a purple solution. 1-Pentanol is added and floats on top as a clear layer due to its lower density and low water solubility. Vigorous shaking for a few seconds causes the alcohol to mix with the other reagents and extract the methyl red. Upon standing, the alcohol layer reseparates as a red layer floating on top of the now blue layer of aqueous copper(II). The demonstration is easy to prepare and perform and has an impressive visual impact.

The catalytic hydrogenation of alkenes and alkynes is an important part of the undergraduate chemistry curriculum and is a fundamental process in chemical industry. Inquiry-based laboratory activities are presented that investigate the hydrogenation of alkynes on a nanoparticle palladium surface to form alkenes, which go on to form alkanes. Alkyne hydrogenation using H2 and/or D2 proceeds via a vinyl–palladium intermediate to form a π-bonded alkene–Pd species that can desorb or remain on the palladium surface and undergo further hydrogenation via the Horiuti–Polanyi mechanism, associated with extensive deuterium–hydrogen exchange. Central to the experiments is an inexpensive, easy-to-build glass tube containing palladium nanoparticles on alumina beads that can be used indefinitely. A total of seven inquiry-based questions are discussed regarding hydrogenation of alkynes. A similar number of open questions are discussed for further investigations by interested persons. These activities are suitable as guided research projects for science majors. Each experiment is performed by groups of two or three students in about an hour including analysis by mass spectrometry. An additional hour is allowed for student analysis and discussion of the mass spectral results, writeup, and future planning followed by about 30 min with the mentor for group presentation and discussion of the results. Results often lead to additional questions, either for clarification or for new exploration and form the basis for inquiry-based learning and problem-solving.

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Thomas Graham discovered the law that bears his name while studying gas diffusion into air and other gases. He also found that the same relationship held with gas effusion, the movement of gases through a pinhole into a vacuum. Modern understanding of diffusion and effusion is based on kinetic-molecular theory, and it is generally accepted that Graham's law as originally stated holds for effusion. Diffusion is more complicated, involving intermolecular collisions and composition gradients. This article describes a simple laboratory activity in which diffusion of gases into air though an open syringe is studied over time. The activity could be adapted and modified into an inquiry-based independent study activity or undergraduate research project.