Area Of Chemical Kinetics Research Articles

Examining Students’ Ability to Solve Algorithmic and Pictorial Style Questions in Chemical Kinetics

The published study of Nurrenbern and Pickering in 1987 raises awareness among chemistry educators that students’ success in answering numerical questions does not necessarily reflect their degree of understanding of the related chemical concepts. Efforts have been made to provide more opportunities for students to improve their ability in answering pictorial questions in many studies in the hope that this will explore their conceptual understanding. The aim of this study was to examine the difference between students’ ability to answer algorithmic and pictorial type questions of equivalent content and level in the area of chemical kinetics. The respondents involved in this study were 335 Indonesian and UK university chemistry students. Equivalent algorithmic and pictorial question pairs in the topic of chemical kinetics were designed within a four-tier instrument. The results confirm that students’ ability to respond to the two types of questions is significantly different. The scores obtained by students in the two types of questions indicate that students’ performance in algorithmic questions is better than their performance in pictorial questions. The implications for teaching and learning chemical kinetics are also discussed.

An Overview on Recent Trends in Catalysis

Copyright: © 2014 Shehadi IA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The vast majority of chemical and biological activities and processes involve catalytic steps. Catalysis (homogeneous or heterogeneous) play an important role for chemicals manufacturing, utilizing of energy resources, energy conversion systems, devices and environmental control system, biological activities and drug discovery and design. However, the most important issues in any catalytic process are the activity and the selectivity of the catalysts by which processes are performed. In order to understand and control how a catalysts function, one must understand the energy profile through which the catalytic processes must go through. The energy content and transfer of any catalytic processes is easily understood by applying the principles of thermodynamics which provides an insight whether the process is attainable or not. Therefore, thermodynamics is used to describe the macroscopic behavior of chemical systems through understanding the properties of atoms and molecules. The area of thermodynamics is fully established and all laws that govern the energy flow and transfer are developed. Alternatively, the routes and the rate of the chemical processes happening are not yet fully comprehended. Hence, the application of chemical kinetics to understand catalytic activity and selectivity is still under investigation. Moreover, tremendous amounts of scientific discoveries are continually being achieved and more are to be revealed in the years to come. Even though a unifying principle has been identified in the area of chemical kinetics and compiled, but none are faultless. Each principle has its own defects and limitations. Understanding the mechanistic behavior of chemical systems in general and catalysis in particular, lead to significant discoveries in current scientific research. These days, scientists can study, monitor and characterize fast and ultra-fast reactions using laser pulses involved in numerous techniques. One of the most prominent areas of catalytic research these days is to understand the electronic and ionic transfer in biological systems. Functional ion channels in particular are the focus of many recent catalytic research works directed to understand gating, closing and filtering mechanism of the channel. In order to understand the basic channel mechanics, researchers have focused upon questions surrounding the functioning, selectivity, and gating mechanisms of ion channels. Another attractive area for research is to study electron transfer in proteins and enzymes in order to understand functions and properties. Such areas have boomed after the discovery of the genomic code of many living organisms which led to the discovery of thousands of proteins and enzymes of unknown functions and structures. However, recent advances in biophysics especially in X-ray crystallography, high-resolution electron microscopy and molecular biology have helped shed light on some of the issues in scientific quests.

Applications of quantitative laser sensors to kinetics, propulsion and practical energy systems

Laser diagnostic techniques play a large and growing role in combustion research and development. Here we highlight three areas where quantitative sensing based on laser absorption has had strong influence: chemical kinetics, propulsion, and practical energy systems. In the area of chemical kinetics, measurements in shock tubes of high-temperature reaction rate coefficients using species-specific laser absorption techniques have provided new and accurate answers to questions about combustion chemical processes. In the area of propulsion, wide-bandwidth measurements of flow temperatures, species concentrations, and velocity have provided engine designers with the necessary information to improve operation and performance. In the area of practical energy systems, real-time measurements of combustor operating conditions and emissions have enabled needed incremental improvements in large power plants and improved safety of operation. Yet, there is still more to be done, and opportunities for new applications will grow as laser sensors evolve. This review seeks to provide an overview of the current power and future potential of these modern diagnostic tools.

Synthesis of Nano-Scale Photocatalyic TiO2 Powder Doped withAg by Sonochemistry Reaction

In chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems. In the area of chemical kinetics, it has been observed that ultrasound can greatly enhance chemical reactivity in a number of systems by as much as a million-fold. Nano-technology is a super microscopic technology in which structures of 100 nanometers or smaller can be investigated. This technology has been used to develop <TEX>$TiO_2$</TEX> materials and <TEX>$TiO_2$</TEX> devices of that size. Thus far, electrochemistry methods and photochemistry methods have generally been used to create <TEX>$TiO_2$</TEX> nano-size particles. However, these methods are complicated and create pollutants as a by-product. In the present study, nano-scale silver particles (5 nm) were prepared in a sonochemistry method. Sonochemistry deals with mechanical energy that is provided by the collapse of cavitation bubbles that form in solutions during exposure to ultrasound. <TEX>$TiO_2$</TEX> powders 25 nm in size doped with Ag were formed using an ultrasonic sound technique. The experimental results showed the high possibility of removing pollution through the action of a photocatalyst. This powder synthesis technique can be considered as an environmentally friendly powder-forming processing owing to its energy saving characteristics.

Anti-Correlation Approach to Model-Based Experiment Design: Application to a Biodiesel Production Process

Advanced model-based experiment design techniques are a reliable tool for rapid development and refining of process models, in particular in the area of chemical kinetics. The high parameter correlations, which are typical of the most common reaction networks (parallel, consecutive reactions, etc.), often make the identification and proper estimation of the model parameters extremely difficult. For this reason, a novel approach to model-based experiment design able to yield optimally informative experiments while simultaneously reducing the correlations between the model parameters was proposed in a previous publication1 and was demonstrated to be highly effective. This article presents the application of this novel anti-correlation approach to the identification of a kinetic model for biodiesel transesterification from rapeseed oil, using isothermal experiments. The actual, as opposed to simulated, execution of laboratory experiments provides a further and much more significant demonstration of the effectiveness of our innovative design method. By following the suggested algorithm, three experiments were optimized for each of the two design iterations, providing statistically validated estimates for the six kinetic constants involved in the model with, on average, a medium correlation level.

Use of Models in Determining Chemical Pharmaceutical Stability

The area of chemical kinetics as it has been applied to the prediction of the stability of drugs in pharmaceutical formulations has been quite extensively discussed and reviewed during the past few years. In spite of this, a method has been developed which will, it is hoped, be especially useful in pharmaceutical product development work as distinguished from academic research studies in which the goals are to determine reaction rates or orders or to elucidate reaction mechanisms. The present method is based upon the construction of reference reaction paths which result logically when one considers the usual values of pertinent heats of reaction and considers normal shelf-life goals. Two results which have emerged from consideration of these paths are rules of thumb having a sound theoretical basis and a naturally arising logical assay schedule. The schedule arises because of the temperatures chosen for sample storage (RT, 37°, 45°, 60°, and 85°) and would change if another set of storage conditions was employed.