A three-dimensional heat transfer model is built according to the rotor structure of an asynchronous motor, and three-dimensional temperature fields of the rotor under different working conditions, such as the unloaded, rated loaded and that with broken rotor bars, are studied based on the finite element numerical method and experiments. The…

This article explores heterogeneity as fundamental to learning. Inspired by Bakhtin's notion of heteroglossia, a design team consisting of an experienced classroom teacher and 2 researchers investigated how a class of 3rd and 4th graders came to understand disciplinary points of view on heat, heat transfer, and the particulate nature of matter.…

Curzon and Ahlborn achieved finite power output by introducing the concept of finite rate of heat transfer in a Carnot engine. The finite power can also be achieved through a finite speed of the piston on the four branches of the Carnot cycle. The present paper combines these two approaches to study the behaviour of output power in terms of…

A simple experiment about thermal effects in chemical reactors is described, which can be used to illustrate chemical reactor models, the determination and validation of their parameters, and some simple principles of heat transfer and sensor dynamics. It is based in the exothermic reaction between aqueous solutions of sodium thiosulfate and…

The International Boiling Point Project is an online, collaborative project for students in grades 6-12 in which they investigate the impact of four factors (room temperature, elevation, volume of water and heating device) on the boiling point of water. A detailed procedure is provided for students in order to limit the number of variables…

"Science Learning and Instruction" describes advances in understanding the nature of science learning and their implications for the design of science instruction. The authors show how design patterns, design principles, and professional development opportunities coalesce to create and sustain effective instruction in each primary scientific…

To determine the carbonation degree of materials used in mineral carbonation experiments, a fast, simple, and sufficiently accurate method is required. For this purpose, a method based on the reaction between carbonates and hydrochloric acid was developed. It was noted that this method could also be used to teach undergraduate students some basic…

In this article we examine three approaches, leading to different conclusions, for answering the question "Does the addition of inert gases at constant volume and temperature modify the state of equilibrium?" In the first approach, the answer is yes as a result of a common students' alternative conception; the second approach, valid only for ideal…

We analysed the heating curve of water which is described in textbooks. An experiment combined with some simple heat transfer calculations is discussed. The theoretical behaviour can be altered by changing the conditions under which the experiment is modelled. By identifying and controlling the different parameters involved during the heating…

This paper discusses how the Carnot engine led to the formulation of the second law of thermodynamics and entropy. The operation of the engine is analysed both in terms of heat as the caloric fluid and heat as a form of energy. A keystone of Carnot's thinking was the absolute conservation of caloric. Although the Carnot analysis was partly…

Melting temperatures of oligonucleotides are useful for a number of molecular biology applications, such as the polymerase chain reaction (PCR). Although melting temperatures are often calculated with simplistic empirical equations, application of thermodynamics provides more accurate melting temperatures and an opportunity for students to apply…

The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer…

Liquid 2-chlorobenzaldehyde was converted, by grinding with potassium hydroxide pellets, into equimolar quantities of solid 2-chlorobenzoic acid and solid 2-chlorobenzyl alcohol in a Cannizzaro reaction. TLC, IR, and NMR experiments, using authentic samples for comparison, confirmed the identity and purity of the two products. Guided-inquiry…

A computational experiment aimed to create and systematically analyze models of simple cation hydrates is presented. The changes in the structure (bond distances and angles) and the electronic density distribution of the solvent and the thermodynamic parameters of the hydration process are calculated and compared with the experimental data. The…

When most materials are heated they expand. This concept is usually demonstrated using some type of mechanical measurement of the linear expansion of a metal rod. We have developed an alternative laboratory method for measuring thermal expansion by using a Michelson interferometer. Using the method presented, interference, interferometry, and the…