The dehydration of 2- or 4-methylcyclohexanol to obtain isomers of methylcyclohexene is a classic organic chemistry experiment. Students perform a distillation, collecting samples to analyze the progress of the reaction. The reaction produces a major product that can be explained on the basis of the regiochemistry of the [pi] bond formation for…

We describe an educational activity that can be done by using smartphones to collect data in physics experiments aimed to measure the oscillating period of a spring-mass system and the elastic constant of the helicoidal spring by the dynamic method. Results for the oscillating period and for the elastic constant of the spring agree very well with…

Supersonic free-fall jumps are excellent examples of kinematics in the context of drag. They have attracted a lot of media, public, and scientific interest. In 2012, Felix Baumgartner jumped from a height of approximately 38.969 km. During his flight he reached a top speed of 373 m/s, becoming the first human to travel faster than the speed of…

In this paper, we show a laboratory experience describing the possibility to build a sensor using a coil to measure small thicknesses of materials with the possibility of measuring temperature simultaneously, with the same built sensor. Its operation is based on the following facts: An electric current (a.c), flows through a coil and a magnetic…

We report on a simple, rapid, and room-temperature undergraduate-level experiment for gold nanoparticle synthesis, analysis, and utilization as a catalyst for the sodium-borohydride-assisted reduction of methylene blue and Congo red dyes. Typical procedures toward gold nanoparticle formation require an elaborate, lengthy synthesis (some requiring…

The concept of equilibrium vapor pressure plays a key role in the general chemistry curriculum; it is among the first and most easily demonstrated examples of equilibrium and frequently caps off the first semester of general chemistry where it illustrates the properties of liquids and intermolecular forces. We report here simple modifications of…

All-solid-state polymer electrolytes (SPEs) have been regarded as an advisible alternative for simultaneously overcoming the safety issues and high energy density demands presented in traditional lithium batteries, and they represent the development orientation of energy storage devices. This course describes the preparation of a cross-linked and…

According to the definition, surface tension could be affected not only by intermolecular interaction but also by molecular area. However, in chemistry textbooks, surface tension is mainly explained only in terms of intermolecular interaction. Although the existing surface tension concept in the textbooks can lead to a variety of counterexamples,…

A classic undergraduate introductory experiment is to measure the diffraction and interference pattern from single and double slits to determine slit width and separation. Studies show that Course-based Undergraduate Research Experiences (CUREs) can make science more inclusive when offered at the undergraduate level. Additionally, CUREs help…

A laboratory exercise for the synthesis of a sulfonated styrene-"co"-maleic anhydride polymer and its application as a stain blocker on nylon-6,10, is described. The effectiveness of the sulfonated polymer to prevent the conjugate base of an acid dye from staining the polyamide is demonstrated. This experiment is designed for…

To study the absorption of ultrasound in plexiglas we propose to use gadgets that are available to each student: an ultrasound humidifier, a liquid crystal display of a pad, a polaroid analyzer, a digital camera, a multimeter with thermocouple, and a stopwatch. These devices allow us to visualize a region in plexiglas where ultrasound is absorbed…

A simple method is described for measuring liquid density based on stretching of the spring and equilibrium of weight and elastic force. The method involves placing a container with liquid under test on the spring causing a stretch of the spring that is directly proportional to the weight of the liquid. With this technique, the liquid density can…

Studying the dynamics of beams is considered an indispensable field for mechanical and civil engineering students. This paper describes, in detail, the use of smartphones in educational practical works to determine and examine the dynamic characteristics of beams subjected to free vibration. Where the smartphone is equipped with a mobile…

Although it originates from the ancient Greeks, optics still arouses a lot of scientific interest, mainly due to the technological innovation associated with it. One of its most interesting applications is related to optical metrology and the characterization of materials through optical techniques. While some of these processes can be explained…

Research into seed germination classroom activities has been common in the last few decades. Didactic proposals have generally focused on the implementation of guided activities in a specific educational stage and context, and an evaluation of the results. However, it is not evident that students approach seed and germination concepts with a…