In this article, it is shown that absolute chemical hardness can be employed to easily show/explain/prove that d5 and d10 electron configurations are indeed more stable than all (from d1 to d10) configurations. Hence, absolute hardness can be employed to explain the apparently “anomalous” and “baffling” Cr and Cu electron configurations that are sometimes “tricky” for many high school and undergraduate basic chemistry students.
Traditional distillation setup collects distillate at a certain distance from the boiling source. This results in loss of product and the situation could be very serious if micro-scale method is employed. By using an innovative design, it is possible to collect nascent distillate immediately after vapor condensation at the boiling source. This is the rationale of designing the Collection of Distillate at the Source (“CDS”) technique. The design not only significantly improves product yield, because cooling water used for condensation can be dispensed with or recycled. This offers a helpful means to enhance students’ “Green awareness”. Two designs using the “CDS” technique are introduced, namely (i) Micro-scale water-less reflux and distillation and (ii) Micro-scale recycled coolant and all-glass reflux and distillation. The first design can be totally homemade with local resources and by acquiring decent workshop skills, details of construction of its various components are provided.
Sodium chloride consists of sodium and chlorine. This sentence shows a common laboratory jargon statement that experts understand because they know that sodium and chloride ions are meant. Young learners, who learned about sodium and chlorine as dangerous or poisonous substances in their initial lessons, look in vain for gray sodium metal and yellow chlorine gas in common salt: They cannot know what is meant. If we establish on the substance level that sodium and chlorine can be obtained from sodium chloride by melt electrolysis, the statement would be correct. Once ions are known, the correct answer would be on the particle level: Sodium chloride crystals consist of sodium and chloride ions arranged in an ionic lattice. The article will show more examples of jargon regarding acid-base reactions, will ask professors about using the jargon in their lectures, gives advice for improving Chemistry education.
Presented is a method of assessment of the oxidation states of atoms in organic compounds. The method is a simple extension of the Pauling´s electronegativity concept and is applied in various types of reactions including the biochemical processes of vital importance like neutralization of free radicals, β-oxidation or functioning of the nucleotide reductases.
In chemistry there are two equivalent ways of describing chemical bonding between atoms in a molecule: On the one hand there are bond forces and on the other hand there are electron pairs. In order to introduce chemical bonding already in early chemistry class without having to relate to the nucleus-shell model of atoms, standard bonding abilities can be defined – e.g. four bonds in case of the C atom within a CH4 molecule or two bonds in case of the O atom within a H2O molecule. Accordingly, proposals for Chemistry education are discussed and ways of instruction compared.
The procedure of assignment of absolute configuration to optical stereoisomers in various projections has been already described in literature. Most common methods utilize the Fischer Projection as the standard and hence demands a three dimensional structure (wedge dash projection, newmann projection, sawhorse projection) to be inter converted to two dimensional planar Fischer Projection. This adds on an extra exercise which may sometimes cause error while specifying Absolute Configuration to a molecule originally represented in three dimensional projections. Hence this assignment of configuration to optical isomers should be directly taught to undergraduates through three dimensional representation of the molecule as stereochemistry deals with three dimensional aspects of an organic compound. This method assigns absolute configuration to the chiral molecules directly in wedge dash projection without interconverting to Fischer Projection.
Chemistry is a field of study in which a lot of experimentation is involving. An experiment is a test carried out under controlled conditions to demonstrate a known truth, to examine validity of a hypothesis and to determine the efficacy of something new. Laboratory experience also gives students an opportunity to observe chemical systems and to gather data useful for the development of principles subsequently discussed in the textbook and in class. However, experimental work is a fundamental part of any science course and this is especially true for chemistry courses. It is vital to know that any one in chemistry should be able to conduct practical work effectively. This paper seeks to offer an overview of the current situation in higher education, and explores what might be the aims for today. It also argues that laboratory work in higher education cannot be seen in isolation. For most students it follows school laboratory experiences which are rapidly changing, and has to relate to material taught in lectures and tutorials. But, learning chemistry by doing practical work at Debre Markos higher education preparatory secondary school is not organized in such a way. So, the researcher needs to conduct this study to explore all things that are happening there. The study employed in both qualitative and quantitative research approaches. The researcher used descriptive research strategy and data were collected by using questionnaire, interview, document analysis, FGD and observation. The sample size of this study is 221; 212 students and 8 teachers, the school administrator and the delegated lab technician were also considered. It was analyzed by percentage, mean value, t-test and one-way ANOVA by SPSS program version 20. The main challenges of DMHEPSS practical works were lack of teachers’ interest and carelessness, lack of wise school administrator, lack of professional lab technician, lack of conducive lab environment were the main challenges that the researcher was discovered. Therefore; motivating and encouraging teachers, training teachers, creating awareness of students on practical works, employing professional lab technician and improving the attitudes of school administrator were solutions to be taken there.
The paper is a continuation of Part (II) of the article [1] published in AJCE Vol 10 No.2, July, 2020. It also advocates the use of “DMM display” technique in which a single piece of instrument, a digital multi-meter (DMM), is used as a terminal display for more than one type of experiment. Sensor circuit design aims at providing a “unit-free” display situation in which students feel less threatening, i.e. a “user-friendly” situation for school-level experimentation. The designed electronic sensor, coupled with an innovative miniature conductivity probe, a combo-well plate and a commercial DMM, is able to numerically display electrical conductivity of aqueous solutions ranging from non-conductive like deionized water as 0 to highly conductive such as 1M H2SO4 as 81, with a complete conductance calibrated at 100. The design allows digital display of conductivity measurement of aqueous solutions without the conventional reading unit of “μS/cm”.
The study was undertaken to examine the effect of blended formative assessment with metacognitive scaffolding strategies on students’ achievement and self-regulation skills in learning Chemistry with focus to secondary schools in Addis Ababa City, Ethiopia. The study adopted pretest posttest quasi-experimental design. Three groups were involved in the study, two experimental and one comparison groups. The experimental groups practiced the formative assessment and blended formative assessment with metacognitive scaffolding strategies respectively, whereas for the comparison group the existing instruction were implemented. The sample, consisting of 132 eleven grade students, was taken by using the multistage random sampling technique from three secondary schools. The Chemistry Achievement Tests (CAT) and the Chemistry Self-Regulation Skills Questionnaire (CSRSQ) were the instruments for data collection. The internal consistency of the CAT was obtained using Kudder Richardson formula 20(KR-20) and the reliability index obtained was 0.79. The reliability coefficient for CSRSQ was estimated using Cronbach alpha and its value was found to be 0.76. For the pre- and post-tests’ data analysis, descriptive statistics (mean and standard deviation) and inferential statistics (Oneway ANOVA) tests were implemented to compare the scores obtained from the experimental and comparison groups. The main finding of one-way ANOVA indicated that there was a significant effect on students’ achievement [F (2,129) = 13.32; p<0.001] and their self-regulation skills [𝐹 (2,129) = 12.38; p<0.001]. Moreover, effect size estimate was used to provide a strong validation on the variation between the three groups for the measure of students’ achievement and selfregulation skills in learning chemistry. Recommendations were made to promote the use of blended formative assessment with metacognitive scaffolding strategies aiming at the improvement of student achievement and self-regulation skills in learning Chemistry at secondary schools.
The aim of this work is illustrating a possible example for explaining the upcycling of waste, hence producing value from it, for possible future use e.g., as viscose in the fashion industry. This has been performed by comparing the results obtained from different cellulose waste, especially yield of the product and its apparent quality. The first objective of the experiments is explaining the chemical procedure to recover cellulose waste for further use. After this, the cellulose extracted is characterized as concerns its morphological structure in terms of dimensions of the fibers obtained. Then, infrared analysis data are compared with those available from previously analyzed cellulose with known composition. Through this experience, the students are introduced to the importance of upcycling in general terms, starting with examples of though they are also presented with the very variable quality of the product obtained from cellulose waste, so to be able to make considerations about the possibility to proceed with the experiment and eventually developing it to an industrial level.
This research explored pre-service science educators’ comprehension regarding the concepts of galvanic cells, electrode potentials, and electrolytic cells in electrochemistry. A sample of 64 first year trainee science educators selected from the Department of Teacher Education at the University of Ghana was strategically chosen to take part in this investigation in the 2018/2019 academic year. In this study, a pre-test / post-test quasi-experimental framework was adopted to determine how “conceptual change texts” (CCTs) would affect the performance of pre-service science educators in electrochemistry. A two-tier 10 multiple-choice questions (MCQs) termed “electrochemistry concept test” (ECT) was given to them. Results showed that they had difficulties interpreting electrolytic cell-related concepts and most could not differentiate electrolytic cells from galvanic cells. The achievement of learners instructed utilising the Lecture method (LM) was lower than those instructed with the CCTs when a post hoc analysis with a Bonferroni adjustment on the ECT was conducted as a follow up to the one-way between-group analysis of variance, ANCOVA. The study offers comparative data on the importance of meaningful learning for enhancing the conception of electrochemistry by learners. The findings suggest that the CCTs inthe experimental group might have caused an increase in pre-service science instructors’ intellectual achievement.
Inorganic qualitative analysis remaining a difficult topic to learn and to teach influences the learner acquisitions. The study investigates utilizing concept maps to remediate prospective physics and chemistry teachers’ understanding of inorganic qualitative analysis, via a pre-and postintervention test methodology. Data were collected from the tests scores and the content analysis of responses. Results show a significant difference between the achieved scores, and a decrease of percentage responses located in 'incomprehension or unanswered' category. The gain scores are very pronounced for the reagents and uses basic (97.2%). This finding supports that the treatment may provide efficiency to remediate participants’ difficulties.
In science education, the inquiry has two distinct sides: 1) teaching and learning science by inquiry, 2) Science as inquiry. Teaching and learning science by inquiry involves the means by which students acquire scientific knowledge. On the other hand, science as inquiry focuses on science as a method by which facts are obtained. This study focused on teaching and learning science by inquiry. Specifically, the purpose of this study was to determine inquiry levels in the Examination Council of Zambia chemistry 5070/3 practical examinations for the period ranging from 2008 to 2018. Both questions in chemistry 5070/3 practical paper for each year were analyzed for levels of inquiry using analysis framework and procedures. Analysis framework and procedures involve two processes; categorizing sentences as experiential and further analyzing the experiential sentences for inquiry potential by considering the four levels of inquiry (confirmation, structured, guided, and open inquiry). An inter-rater agreement coefficient for analysis of the chemistry 5070/3 practical examination was calculated using Cohen’s Kappa (Cohen, 1960). The percentage agreement between the two raters for the chemistry 5070/3 practical examination past papers analyses ranged from 75 to 100% with the corresponding Kappa values from 0.421 to 1.00. This means that there was a high degree of agreement between the two raters in categorizing the levels of inquiry. The results showed that the experiments in chemistry practical examinations were mostly at the structured level of inquiry. The period under review had no experiments focusing on higher levels of inquiry such as open inquiry. These results have implications on science teaching, learning, assessment, and teacher education.
This paper presents a possible use of rocket chemistry (propellants) as a generating theme for teaching chemistry. The well-known “rocket candy” (sucrose-potassium nitrate propellant), KNSu is prepared and it is suggested as his combustion can be employed as a generating theme for teaching chemistry.
The relationships between the properties of gases are not mere curiosities and have important implications in areas such as chemistry, chemical engineering, materials science and engineering, mechanical engineering, aerospace engineering, meteorology, etc. In the present work, we describe a practical device to study the pressure – air temperature relationship in constant volume that can be built and tested by students in the first years of science courses. The simplicity and reliability of the device make the proposal effectively capable of being used in experimental practices in several high school courses, or even in higher education and even in teacher training courses.
This research depended upon the importance of conceptual understanding in bringing about meaningful learning. Accordingly, this research was designed to assess students’ knowledge regarding basic and fundamental concepts in Chemistry: atomic structure, bonding and bonding energy. Therefore, some of year I, II, III Bachelor of Science in Chemistry (BSc (Chem)) and year I life sciences university students were enrolled in this research. According to Novak’s theory of meaningful learning, students were taught first before being tested. Therefore, both year II (n=20) and III (n=14) chemistry students were tested in their first semester, while year I (n=61) chemistry and life sciences students were examined at the end of second semester. The results from the interview with students indicated that almost 94% drew electron cloud and Bohr’s model as their mental image of atomic structure. Furthermore, they used classical mechanics ideas to explain electron cloud, and probability language to explain Bohr representation. Results from questionnaire indicated that, while a fairly good proportion of BSc (Chem) year II and III students involved in this study showed an appreciable level of scientific literacy, more than 50% of the life sciences students had problems in understanding these concepts. Furthermore, this paper discusses misconceptions as revealed in the interview and questionnaire results.
Colloids are an important component of physical chemistry and physical pharmacy curricula. In pharmacy, colloidal systems and concepts are encountered in dosage forms (e.g., suspensions, emulsions) and many drug delivery systems (e.g., nanoparticles). Since colloids may appear rather theoretical in nature and may be difficult to grasp when taught to students for the first time, practical activities are invaluable in teaching this topic. This paper presents some useful activities for classes on colloids that may be incorporated in physical pharmacy and physical chemistry courses.
Our recent exploration of the ideas of student-teachers about DC electric circuits and electrochemical cells has shown the prevalence of numerous misconceptions previously reported in the physics education and chemistry education literature. Our students have developed their concepts throughout the period from grade 6 to BEd III in two separate streams – one essentially in chemistry and the other in physics – despite the reality that a cell and circuit together constitute a system. The potential benefits of adopting a Systemic Approach supported by two Big Ideas of Science Education in addressing the needs of our future science teachers are explored. A joint physics-chemistry topic devoted to the cell and circuit system in the BEd curriculum is proposed.
The performance of virtual laboratory practice in the Metallurgy Engineering of the Technological University Jose Antonio Echevarria, Havana, Cuba, is described. The experience presented was developed in a second-year group, and two laboratory practices were done with satisfactory results. With this activity, the students achieved the skills they need through virtual experimentation. In addition, it was possible to motivate the students to consider the importance of physical-chemical analysis showing the link with computing.
The main objective of the study was to determine Pre-service Chemistry Teachers’ (PCTs) understanding of isomerism related concepts of Aliphatic Hydrocarbons (AHs). To get in-depth picture of PCTs understanding on isomerism related concepts of AHs, case study was employed. The sample for this study consisted of twelve participants selected from 87 PCTs randomly, in two classes. These were second year PCTs registered in Introductory Organic Chemistry I course in Arbaminch College of Teachers Education, Southern, Nations, Nationalities and Peoples Regional State (SNNPRS), Ethiopia in the year 2017 G.C. A semi-structured interview was used for judging understanding of PCTs in relation to isomerism concepts. A framework analysis approach was applied to analyze interview data. The results of analysis revealed that the PCTs in the Intervention Group (IG) had better acquisition of isomerism concepts than those in the Comparison Group (CG). Based on the results and discussions, conclusions were made.
