Common difficulties experienced by grade 12 students in learning chemistry in Ebinat Preparatory School

The objective of this study was to examine the nature and causes of common difficulties experienced by grade twelve students in learning chemistry in Ebinat preparatory school. A qualitative method was employed to investigate the questions, which used interviews and questionnaires with students and teachers. The key findings of the study indicated that students are being more challenged by topics like chemical bonding, thermodynamics, chemical equilibrium, kinetics, and colligative properties. The main factors that are contributed for the learning difficulties in chemistry faced by our students include: absence laboratory works, absence of teaching and learning resources, poor teaching and learning strategies, poor English and Mathematical skills and there is a need to improve these cause by using equip laboratory, improvement in assessment, use of proper English language by teachers etc

Nano Fe3O4–graphite paste modified electrochemical sensor for phosphatic pesticide -chlorpyrifos

A sensitive, cost effective and selective electrochemical sensor has been developed by exploiting iron oxide nano-particles as modifier in the paste of graphite powder. Cyclic voltammetric (CV) and differential pulse voltammetric (DPV) working parameters have been standardized and used practically for the determination of chlorpyrifos (O, O-diethyl O-3, 5, 6-trichloropyridin-2-yl phosphorothioate) pesticide from its aqueous solutions. Both techniques were deployed to investigate the electro-chemical interactions between chlorpyrifos and modified carbon paste sensor along with the redox characteristics at analyte/ sensor interface. The significant enhancement in peak current signals and the improved magnitude of the redox peak potential indicated the awe-inspiring facilitation of the electron transfer process by the modifier at the sensor/ analyte interface. The difference in the redox -potential (ΔEp) and peak current ratio (Ipc/Ipa) have revealed a notable surface enhancement characteristic of the modifier that responds the higher concentration gradient of pesticide at the interface. In lower analyte’s concentration range i.e. from 1.0 to 100μM, the peak current varies directly to the pesticide concentration with detection limit of 2.8 x10-6 mol/L. The relative stability of the modified sensor is fine and the reproducibility of the results is up to 98%, even after a gap of two months. The proposed analytical method is quite successful when applied for the quantification of chlorpyrifos from its aqueous samples. The electrochemical sensing/ detection of the pesticide chlorpyrifos is confirmed by its two electrons redox behavior and the same have been explained by suitable reaction scheme as:Keywords: Nano-iron oxide, Chlorpyrifos, Modified graphite paste, Voltammetry, Electrochemical metho