African Journal of Chemical Education

The steady state in chemical kinetics: Characterization in terms of the first and second steady state rate laws

2024-01-17T10:19:19+00:00

Chemical reaction rate laws facilitate the design and control of chemical processes. In turn rate laws are often arrived at after assumption of the steady state approximation, whereby the steady state is characterized by the First State Rate Law, defined for reactions involving very reactive intermediates, by assuming that the concentrations of the chemical species, involved as very reactive intermediates can be eliminated by equaling their rate of formation to their rate of disappearance, in which case the concentration of the intermediate can be assumed to be constant. In this communication theoretical evidence, as well as experimental evidence from the literature, is presented showing that the steady state can also be characterized by the Second Steady Rate Law based on pseudo-zero order kinetics. In addition, equations are derived showing that the concentration of the steady state intermediate can be expressed in terms of the initial concentration of the reactant, and that the steady state approximation is valid within the kinetic limits bounded by truly first (or second) order rate laws and the truly equilibrium rate law. The article has the following highlights: 1. The steady state in chemical kinetics is defined by the First Steady State Rate Law in terms of the constancy of the concentration of the reaction intermediate, and by the Second Steady State Rate Law in terms of the constancy of the rate of reaction. 2. Both First and Second Steady State Rate Laws can be used as bases for assuming the steady state approximation. 3. The limits of the validity of the steady state approximation are defined.

Combinatorial chemistry in the undergraduate laboratory

2024-01-17T10:23:58+00:00

A practical is presented to familiarize the undergraduate students with a basic concept of the combinatorial chemistry. Using two different phenols as nucleophiles and dichloromethane as electrophile in basic medium, the mixtures of three possible substitution products are obtained which are easily separable.

Teachers’ perceptions and implementation of inquiry based learning in rural schools

2024-01-17T10:40:12+00:00

An inquiry approach is a student-centered approach that seeks to enhance learners’ conceptual understanding of scientific concepts and acquisition of scientific process skills. This study explored how Chemistry teachers perceive and implement the inquiry approach in rural schools. Guided by the pragmatist philosophy, the study adopted the mixed-method approach and utilized the sequential explanatory design. Data were collected from 15 chemistry teachers in the Gweru district using questionnaires, interviews, classroom observations, and document analysis. Quantitative data from the questionnaire were analyzed descriptively while qualitative data were analyzed thematically. The results of the study revealed that chemistry teachers have positive and favorable perceptions about the implementation of the inquiry approach however, its enactment in the classroom is limited extent due to a number of constraining contextual factors. In addition, chemistry teachers are still hesitant to shift from the transmissive paradigm of teaching toward a more learner-centered approach. Furthermore, the teachers were shown to have limited knowledge and skills in the practical implementation of inquiry instruction. The study recommends professional development training and support of chemistry teachers on the practical implementation of inquiry-based learning to enhance their pedagogical content knowledge and skills.

Assessment of water quality parameters in Nyambai, Brikama, The Gambia

2024-01-17T10:45:40+00:00

This study took place at Nyambai, Brikama, The Gambia. It was with a view to ascertaining the cause of problems with well water at the named location as complained by some inhabitants in an earlier study. Twenty well water samples were collected randomly, and nine water quality parameters were measured in each sample: nitrite, E-coli, conductivity, pH, hardness, manganese, cyanide, phosphate, and total dissolved solids. E-coli counts exceeded World Health Organization, WHO recommendation. This was attributed to violation of recommendations of distance between well water and toilet/dumpsite. All measured pH values were acidic; one sample site exceeded recommended conductivity values. All other parameters were within the National Environment Agency, The Gambia, guidelines. Nearly all wells in the study were open and had an average sanitary condition. Gambia Government needs to sensitize populace about the need to close wells and respect regulation of distance between well and dumpsite/toilet when constructing homes. Further to this, is the need to manage waste.

Essential nanoscience in graduate education: An outline

2024-01-17T11:03:38+00:00

The purpose of this paper is to impart cross-disciplinary guidance and training to students in the rapidly developing nanoscience and nanotechnology area. This specially designed course projects a prismatic view to introducing the synthesis, properties, structure, bonding, and important applications of nanoparticles in different fields in meeting academic objectives. The various fundamental and applied aspects of nanoparticles are discussed that are of interest in the chemical education experience and also cover environmental concerns for their educational value. Seminar presentation, laboratory experimentation, and careful assessments of students’ performance constitute very important components of this graduate-level course to enhance subject matter knowledge and other sector- specific skills. The syllabi developed signify an attempt to help students to understand the basic importance of nanoparticles in different fields and create proper awareness about the applied aspects in a wide range of applications through illustrative examples. This paper attempts to promote integrative learning to impart better education and outline the four important participatory aspects (four L’s) of learning-lecture, laboratory, library, and life to bring about educational transformation in students under a single scientific theme. The course content and structure promote the students to get ready for the real challenges of actual interdisciplinary research in the current world environment as an effective approach.

Editorial

2024-01-17T09:44:14+00:00

No Abstract