The UV--vis absorption of cyanine dyes is a common experiment in many physical chemistry teaching laboratories. As part of the analysis, students are often asked to hypothesize why the predicted absorption differs from the measured values and why dyes which are predicted to have the same absorption have measured values which differ from each…

In school chemistry, the oxyhydrogen or "Knallgas" reaction is used to provide evidence of hydrogen gas in the squeaky pop test. However, the test actually indicates the presence of an explosive gas mixture of hydrogen and oxygen (oxyhydrogen gas) rather than pure hydrogen. The sheer observations of an explosive reaction and the…

A simple, safe, and easy demonstration of the reaction of sodium peroxide with water is presented. The reaction is performed in a plastic bottle by adding water to sodium peroxide supported in a rubber "thimble"; oxygen is detected by the reignition of a glowing splint, while the generation of sodium hydroxide is indicated by…

The preparation of ethyl acetoacetate is a distinctive, century-old classic organic chemistry laboratory project. Ethyl acetate and sodium metal (sodium ethoxide) are reacted by Claisen ester condensation to produce the sodium salt of ethyl acetoacetate and then obtain the refined product by acidification as well as washing, drying, and…

The area of application of electrospray ionization mass spectrometry (ESI-MS), usually coupled with liquid chromatography, seems to be much larger than those of any other ionization method. It gives rise to the demand for new teaching methods that would effectively help students to master the principles of working with and making full use of the…

Experiments that explore quantum principles while utilizing and reinforcing previous synthesis skills are excellent for engaging students and promoting the interconnected nature of chemistry. This experiment utilizes sophomore-level organic synthesis techniques to have students produce their own "meso" substituted porphyrins. The UV-vis…

Colloidal stability is one of the most important criteria in the application strategy of colloidal nanoparticles in the continuous phase. The branches include ecology, involving coagulation as a purification method; medicine as nanocarriers; biology as blood coagulation, etc. A chemist versed in these concepts is a high-performing chemist in…

In the environment, communication among microorganisms is a key aspect of their lives. Through communication, single cells of a microbial population can coordinate their gene expression and, in consequence, their physiology. Quorum sensing systems (QS) are one of these mechanisms that allow this communication through the production and detection…

At-home chemistry experiments are increasingly important to enable high-quality online and hybrid instruction. These class modalities provide significant challenges and also dramatically expand the accessibility of education to those who work or care for family during traditional school hours or have significant commutes to campus. This work…

The importance of teaching the Luria-Delbrück experiment to biology students is increasingly recognized by educators, and improved pedagogical methods for teaching the classic experiment have been proposed and tested in the classroom. However, there are still obstacles that impede the proper teaching of the classic experiment. This note proposes…

It is well known that the needle of a compass in a magnetic field deflects, and that a compass near a conductive wire carrying a stable electric current deflects its needle. The only explanation of this observation is that the current-carrying wire creates a magnetic field around it. The strength of the magnetic field at any point near the wire…

If a ball rolls in a circular path on a horizontal surface at constant speed then its horizontal rotation axis changes direction with time. A simple experiment is presented showing that the torque applied to the ball is equal to the rate of change of its angular momentum, even though the magnitudes of its angular velocity and angular momentum…

Ion transport, involving the diffusion and migration of ions within the electrolyte, stands as a fundamental concept in electrochemistry and serves as the driving force for electrochemical reactions. Electric double layers are critical in the fields of electrochemical energy storage and chemical conversion, constituting a central focus of…

Experiments involving RC circuits are an integral part of introductory physics courses. Previous articles using RC circuits describe determining the charge on a Van de Graaff generator, measuring currents and voltages in a charging RC circuit using a multimeter or an Arduino, measuring the decay constants of complex RC circuits, and using the…

A smartphone is a powerful learning aid in the hands of a large section of students around the world. The camera of the phone can be used for several learning purposes apart from its obvious purpose of photographing. If the focal length of the lens of the camera can be determined, several experiments in optics can be performed with it. In some…