College of Natural and Computational Sciences
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Item Investigating the Impact of Laboratory and Practical Activities on Chemistry teaching and Learning: A Case Study of Grade 10 Students at Weldu Negus Secondary and Preparatory School(Mekelle University, 2024-11-25) Geberemariam Fissha AbebeChemistry laboratory activities play a crucial role in enhancing students’ understanding by providing hands-on experience that reinforces theoretical knowledge. This study examines the impact of laboratory-based teaching on student performance and attitudes at Weldu Negus Secondary and Preparatory School. A quasi-experimental research design was employed, where 263 Grade 10 students were divided into experimental and control groups. The experimental group engaged in hands-on laboratory activities, while the control group received only theoretical instruction. Data were collected through questionnaires, interviews, and post-test assessments, and statistical analysis was conducted using SPSS. The findings revealed that students in the experimental group demonstrated a significant improvement in their post-test scores, with 88.65% scoring above 50, compared to 54.54% in the control group. This highlights the effectiveness of laboratory-based instruction in improving student comprehension and engagement. Despite these benefits, several challenges were identified, including a lack of laboratory equipment and chemicals, insufficient trained personnel, time constraints, and limited teacher preparedness. Additionally, 61.9% of students expressed disinterest in laboratory activities, indicating the need for more engaging and student-centered approaches. Based on these findings, the study recommends improving laboratory facilities, providing professional development for teachers, integrating student-centered teaching methods, and increasing student motivation through real world applications of chemistry. Collaboration with external institutions and regular monitoring of laboratory practices are also suggested to sustain improvements in practical chemistry education. Future research should explore the long-term impact of laboratory-based learning on student career choices and the effectiveness of digital and virtual labs as supplementary tools. Implementing these recommendations will create a more effective learning environment and foster deeper scientific understanding among students.Item EFFECT OF COOPERATIVE LEARNING ON STUDENTS’ ACADEMIC ACHIEVEMEN IN CHEMISTRY ON THE TOPICS OF CHEMICAL EQUILIBRIUM AND PHASE EQUILIBRIUM: THE CASE OF KELLEM PREPARATORY SCHOOL, KELLEMWOLLEGA ZONE, OROMIA REGIONAL STATE, ETHIOPIA(Mekelle University, 2025-01-25) GUTA DEGU DISASAThe study investigate effects of cooperative learning on students’ academic achievement in chemistry on the topics of chemical equilibrium and phase equilibrium: The case of Kellem preparatory school, Kellem Wollega zone, Oromia regional state, Ethiopia. The study sampled 120 students from two sections one taken as experimental group and the other as control group which are purposively selected from six sections of Kellem Preparatory School grade 11 natural science because of relatively low score in chemistry. The data obtained from 60 students (M=29 and F=31) participated in cooperative learning instruction methods and 60 students (M=30 and F=30) participated in instruction based on regular learning methods, 2 School administrators and 2 Chemistry teachers. The research was used experimental methods, questionnaire and interview for data collection. Data analysis was done descriptively using mean, frequencies, percentages and t-test. A pre-test was administered before the study to identify students’ prior knowledge. Sample students score an average academically achievements 60.12% of control group (M=30.06% and F=30.06%) and 60.4% of experimental group (M=29.20% and F=31. 20%) before the treatment. A post- test was administered after cooperative learning instruction methods in order to examine the difference in achievements. In the comparison of the post –test of the two groups, the experimental groups were an average of 81.44 % (M=39.36% and F=42.08%) of academic achievements and 62.52% of control group (M=31.26% and F=31.26%) academic achievements in selected topic. The result of study show that cooperative learning instructional methods was better than the regular method of instructional methods in increasing students’ academic achievements and promote face to face interaction, creating positive dependence and insuring the active participation of all students in activities.Item Comparative Assessment of Heavy Metal Levels in the Soil and Some selected Edible Fruits (Orange and Papaya) Grown in the Addiha Irrigational site, Kola Tembien-Woreda Tigray, Ethiopia(2025-03-25) Gebremeskel Welegebrial HagosEdible fruits (orange and papaya) are source of vitamins, minerals and organic acids which provide an excellent health promoting nutrients. Heavy metals are natural constituents of the Earth's crust and their excessive consumption levels can be damaging to the organisms. The objective this study was compartive assessement of heavy metals (Fe, Zn, Cu, Cr and Mn) in the soil and selected edible fruits (Orange and Papaya). The sampling methods of this study were randomly and targeted methods.The chemicals used in this study were HNO3, HClO4, HCl and distilled water and the materials used inthis study were cutters, sample containers (plastic bags), gloves, hot plates, beakers, test tubs, electrical balance, spoon, stirrer, sample cells, oven, sample holder, volumetric flask and digester. The study was assessed heavy metal (Zn, Cu, Cr, Mn, and Fe) in both soil and selected edible fruits (orange and papaya) grown in the Addiha irrigation site Kola Tembien woreda central zone of Tigray, Ethiopia. Soil analysis revealed that Zn, Cu, and Mn were below established WHO (2011) safe limits, while Cr and Fe exceeded them. In contrast, all heavy metal levels in the selected edible fruits (orange and papaya) were below the established WHO (2012) safe limits. T-tests showed statistically significant differences (p<0.05) for the concentration level of heavy metals Zn, Cr, Mn, and Fe, but the heavy metal Cu is not statistically significant (p>0.05), while the analysis using ANOVA showed significance for all elements when comparing soil to fruit which between soil and orange and between soil and papaya were statistically significant differences (p<0.05). Transfer factors between soil and edible fruits (orange and papaya) varied, with Zn being highest in both. Strong positive correlations were also observed between heavy metal levels in soil and those in the selected edible fruits. The correlation coefficients of soil and orange are (0.9877) and soil and papaya is (0.99932). ANOVA revealed statistically significant differences (p<0.05) between orange and papaya fruits for the mean concentration of heavy metals except Cu at (p<0.05) for Zn, Cu, and Fe, but not for Cr and Mn (p>0.05). Furthermore, ANOVA comparisons between orange and soil, as well as papaya and soil, showed statistically significant differences for all heavy metals (Zn, Cu. Cr. Mn and Fe) (p<0.05). Keywords: Heavy metals, Edible Fruits, Soils, Permissible levelsItem THE CHALLENGES OF CHEMISTRY LABORATORY PRACTICES AND THEIR SOLUTIONS IN THE CASE OF CISTERCIAN MONASTERY MARIAM TSION SECONDARY SCHOOL, BOLE SUB CITY, ADDIS ABABA, ETHIOPIA(Mekelle University, 2025-01-25) Zeray WelegerimaChemistry laboratory practices are essential for reinforcing students' understanding of scientific concepts and developing critical practical skills. However, educational institutions in developing countries often encounter significant challenges in maintaining well-equipped and functional chemistry laboratories. This study investigates the challenges faced in chemistry laboratory practices at Cistercian Monastery Mariam Tsion Secondary School in Bole Sub City, Addis Ababa, Ethiopia, and explores feasible solutions to address these issues. A mixed-methods research approach was employed, incorporating both quantitative and qualitative data collection techniques. Surveys were conducted among chemistry teachers and students to assess their perceptions of the prevalent challenges. The findings indicate several key issues, including inadequate laboratory equipment and supplies, outdated or malfunctioning apparatus, limited laboratory space, and insufficient safety protocols. Additionally, challenges related to teacher training, student engagement, and overall laboratory management were identified. Based on these findings, the study proposes a multifaceted strategy to address these obstacles. Recommendations include securing funding for laboratory upgrades, implementing systematic equipment maintenance and replacement plans, providing extensive training for teachers and laboratory technicians, and improving student safety awareness and hands-on participation in laboratory activities. This study contributes to a broader understanding of the difficulties faced by secondary schools in developing countries in implementing effective chemistry laboratory practices. The proposed solutions offer valuable insights for policymakers, school administrators, and educational stakeholders in formulating strategies to enhance the quality of chemistry education and laboratory experiences for students.Item ASSESSMENT ON PHYSICOCHEMICAL QUALITY OF TAP AND BOTTLED WATER CONSUMED IN MEKELLE CITY, ETHIOPIA(Mekelle University, 2025-01-25) Tenagne Jiru MergiaWater is a vital resource for human survival. Clean drinking water is a basic need for good health. In this study the levels of six heavy metals, nine common ions and five physical parameters in four different brands of bottled water samples and two tap water samples from different sources that are consumed in Mekelle, Ethiopia were investigated. Concentrations of Fe, Zn, Cu, Cr, Pb, Cd, Ca and Mg were determined by atomic absorption spectroscopy. UV – spectrophotometry was used for the determination of common anions (F-, Cl-, NO3-, SO42- and PO43-) and levels of common cations (Na+ and K+) were determined by flame photometry. The mean concentration of Fe, Cu, Zn, Cd, Pb, Na+, K+, Ca2+, Mg2+, F , Cl-, NO3-, SO42-, PO43-, TDS, TH, Turb, EC and pH in water samples were found in the range (0.82-0.9433), (0.39-0.6693), (0.055-0.2027), (0.0147-0.0213), (0.45-0.6567), (1.63 23.55), (0.01-2.75), (0.117-121.7), (0.073-15.33), (0.0019-0.153), (0.81-16.523), (0.15-6.1033), (0.2366-241.67),(0.0186-0.0286), (1.32-641.29), (0.5-365.33)mg/L, (0.01-0.34)NTU, (8.77 898.33)µs/cm and (6.52-7.33) respectively. All the selected heavy metals (except Zn) were not detected in all bottled water samples. All the heavy metals were detected in both tap water samples except Cr which was not detected in tap water sample from Gerebsegen source (GS-1). All common anions (except F- and PO43-) and all common cations were detected in all water samples analyzed. PO43- was not detected in all bottled water samples and F- was not detected in BW1, BW3 and BW4. Common cations (Na+, Ca2+ and Mg2+) and common anions (Cl-, NO3- and SO42-) were found to be higher in BW4 than other bottled water samples. Concentration levels of all the heavy metals and common ions were found to be higher in the tap water samples than bottled water samples. Concentration levels of all common cations (except K+), all common anions (except PO43-) and levels of all heavy metals (except Cu) were found to be higher in tap water sample from Aynalem source (AN-1) than tap water sample from Gerebsegen source. Detected concentrations of Cu, Zn, Cr and all common ions in all water samples analyzed were below the maximum contaminant level proposed by WHO. Concentrations of heavy metals: Fe, Cd and Pb in tap water samples from both sources exceeded the maximum permissible limit set by WHO. Hence all the tested bottled water samples are safe for drinking purpose.Item BIODIESEL PRODUCTION FROM CASTOR SEED OIL THROUGH TRANSESTERIFICATION WITH METHANOL USING WASTE CHICKEN EGGSHELL AS A NATURAL HETEROGENEOUS CATALYST(Mekelle University, 2025-01-25) KINFE GEBREGERGIS GEBREMEDHINhe depletion of fossil fuel reserves and growing environmental concerns have increased interest in developing renewable and sustainable energy sources. Biodiesel, a clean-burning alternative fuel derived from vegetable oils or animal fats, has emerged as a promising solution to reduce the dependence on conventional diesel. This study investigates the feasibility of producing biodiesel from castor seed oil through transesterification using waste chicken eggshells as a natural heterogeneous catalyst. Castor seed oil was extracted from castor seed using ethanol. The eggshell catalyst was prepared by calcining chicken eggshells at 900°C for 3 hours to obtain calcium oxide. Different proportions of the parameters methanol-to-oil ratio and calcined waste chicken eggshell catalyst were taken during transesterification to produce biodiesel. The castor oil from 100 g castor seed extraction yielded 46% (48.4 ml). The highest biodiesel yield was observed during the transesterification reaction when the methanol-to-oil ratio was 9:1, and catalyst loading was 3 wt.%. Under these conditions, the biodiesel yield reached 81.6%. Three repeatable reactions were taking place using the optimized catalyst (3%) and their deviation became 1.4. This indicates calcined waste eggshell catalyst exhibited reusability, making it a viable option for the industrial-scale production of biodiesel from castor seed oil. The physicochemical properties of castor biodiesel were changed from castor oil ( density from 0.951g/ml to 0.881 g/ml, viscosity from 132 mm2/sec to 10mm2//sec, and acid value from 3.86 to 0.950). The fuel property test confirmed that the transformation of castor oil into castor biodiesel. In the XRD characterization, the strong peak pattern occurred at 2θ =30º corresponding to the miller index (1 0 4) in the uncalcined waste chicken eggshell and completely disappeared at the XRD peak pattern in calcined waste eggshells. The FT-IR spectra of Castor biodiesel showed an absorption band at 1742 cm-1, 1460 cm-1, and 1166 cm-1 that indicates the ester carbonyl group (-C=O), methoxy group(-OCH3). and ester functional group (C-O-C). The GC-MS spectra recognize 98.4% FAME, 0.6% FAEE, and 0.7% acids. This research demonstrates the potential of utilizing castor seed oil and chicken eggshells for the sustainable production of biodiesel, contributing to the development of renewable energy and circular energy.Item Characterization of carbonized and uncarbonized bone waste: Physicochemical properties and their potential as alternative energy sources(Mekelle University, 2025-01-25) Haftu Gebremedhin GebremariamOne of the significant challenges facing societies today is meeting the growing energy demand for transportation, heating, lighting, and industrial processes, which have a considerable environmental impact. Population growth and urbanization have both directly and indirectly increased energy demand. This study investigates the characterization of carbonized and uncarbonized waste bone, examining their physicochemical properties and potential as alternative energy sources, particularly for use in the cement industry. The research utilized two laboratory techniques: proximate analysis to determine the physical properties and calorific values, and ultimate (elemental) analysis to assess the chemical composition, including hydrogen, carbon, nitrogen, oxygen, and sulfur content of both carbonized and uncarbonized bones. The results indicated that the moisture content, volatile matter, and fixed carbon of carbonized and uncarbonized bones were 1.35% vs. 2%, 55.65% vs. 50.22%, and 2.55% vs. 7.72%, respectively. The calorific values were 3,212.75 kcal/kg for carbonized bones and 4,018.01 kcal/kg for uncarbonized bones. In terms of elemental composition, carbon content was 32.46% for carbonized bones and 38.13% for uncarbonized bones, while nitrogen levels were 0.99% and 1.10%, and sulfur content was 0.18% and 0.078%, respectively. Comparative analysis of greenhouse gas emissions revealed that uncarbonized bones emitted 1.10% nitrogen, 38.13% carbon, and 0.078% sulfur, compared to 9.67% nitrogen, 58.84% carbon, and 0.25% sulfur from coal. The study concludes that uncarbonized bones are more favorable as an alternative energy source compared to carbonized bones, as they offer comparable emissions and higher calorific values. It is recommended that partial replacement of fossil fuels with bone-derived energy could offer both environmental and economic benefits, promoting cleaner, cost-effective energy solutions.Item Assessment of the physicochemical characteristics of honey collected from Dalocha Woreda, SNNP, Ethiopia(Mekelle University, 2025-01-25) Getachew Asfaw MelkaHoney is the natural sweet substance produced by honeybees from the nectar of blossoms or from the secretion of living parts of plants or excretions of plant-sucking insects from the living parts of plants. The present study aimed to assess the physicochemical characteristics of honey collected from Dalocha Woreda, SNNP, Ethiopia. The honey samples collected from different Kebele’s of Dalocha woreda were of different colors (red and white honey). The collected samples were analyzed for their pH, free acidity, color, electrical conductivity, moisture content, ash content, specific gravity, water-insoluble solid, reducing sugar, sucrose content, hydroxymethylfurfural (HMF), and some selected metal contents of Zn, Mn, Fe, Ni, Pb, Cr, and Cd. The result of physicochemical analysis showed pH in the ranges of 3.98-4.6, free acidity in the ranges of 16-27 meq/kg, color in the ranges of 66.67-128.67 mmpfund, electrical conductivity in the ranges of 0.29-0.79 mS/cm, moisture contents in the ranges of 17.3-18%, ash contents in the ranges of 0.25-0.41 g/100 g, specific gravity in the ranges of 1.35-1.412, water insoluble solid in the ranges of 0.27-0.6 g/100g, reducing sugars in the ranges of 66.58-77.04 g/100 g, sucrose in the ranges of 2.134-4.29 g/100g, and HMF contents in the ranges of 0.455 4.67 mg/kg. Almost all samples of honey examined were within the acceptable range of Ethiopian standards (ES) and World Health Organization (WHO) standards, except for water insoluble material which was poor mainly due to a lack of appropriate handling during harvesting and storage of the product. However, it was observed that there was a significant difference among these tested parameters for these honey samples. The metal content of the honey samples was also found (in mg/L) Zn in the ranges of 2.07-9.69, Pb in the ranges of ND 0.1, Mn in the ranges of 1.9-6.83, Cr in the ranges of 0.35-0.6, Fe in the ranges of 42.28-61.41, Ni below detection limit (BDL) and Cd BDL. The highest concentration was observed for Fe and the lowest concentrations were observed in Pb, Ni, and Cd. Most trace metals are within the acceptable range set by national and international standards except Pb and Cd contents in some samples that need further study.Item A Study of the Impact of Feedback-Integrated Continuous Assessment on Grade 12 Students’ chemistry achievement: The case of Medhanealem Preparatory School, Addis Ababa, Ethiopia(Mekelle University, 2025-01-25) BIRUK GEMECHU ABEBEFeedback is often overlooked in continuous assessment despite its potential to enhance student outcomes. This study examines the impact of feedback-integrated continuous assessment on Grade 12 students' chemistry achievement at Medhanealem Preparatory School in Addis Ababa. The study involved three groups: two experimental groups (one with feedback-integrated continuous assessment and one with continuous assessment without feedback) and one comparison group (traditional exercises and activities). A mixed-methods approach was used, combining quantitative (quasi-experimental) and qualitative (case study) data. Instruments included pre- and post-achievement tests and semi-structured interviews with teachers from the experimental groups. Data were analyzed using SPSS (version 26), applying One-way and Two way ANOVA, and Pearson Correlation tests to compare group scores. Post-test results revealed a statistically significant improvement in the experimental groups compared to the comparison group (p < 0.05). A significant relationship was also found between continuous assessment scores and post-test outcomes. Qualitative data from interviews and classroom observations highlighted that feedback-integrated continuous assessment positively influenced students' chemistry achievement. The study suggests that incorporating feedback into continuous assessment allows teachers to adapt instruction to better meet individual student needs, ultimately improving learning outcomes. Based on these findings, it is recommended that teachers design feedback-oriented assessments aligned with curriculum objectives and clearly communicate performance expectations to enhance student learningItem Detoxification Effect of Rosemary Leaf Powder on Repeatedly Deep-Fried Hayat Palm Oil for Potato Chip Production(Mekelle University, 2025-01-25) ASSEFA MIESHO GEBREDeep-frying with vegetable oils, particularly Hayat palm oil (HPO), is widespread activity in Tigrai; Northern Ethiopia. However, frequently frying with HPO can generate harmful chemicals to health. Therefore, the purpose of this study was to assess the detoxification effect of rosemary leave powder on HPO used for the preparation of potato chips. Different frying cycles (1st, 3rd, 5th, 7th, and 9th) with and without rosemary powder were employed for frying 500 g of row potato at 180 oC in 2L of Hayat palm oil at different doses of 100,150, 200, 250, and 300 mg/kg rosemary powder for 20 min. Oil samples were taken at 1st, 3rd, 5th, 7th, and 9th frying days. The result of the analyzed physical parameters such as moisture content for fried Hayat palm oil without rosemary (FHPO) was found in the ranges of 0.73 to 1.265% while fried Hayat palm oil with rosemary (FHPOR) varied from 0.19 to 0.538% and specific gravity from 0.8906 to 0.9226% for FHPO and 0.8868 to 0.9121% for FHPOR. The refractive index for FHPO was also recorded from 1.459 to 1.547, but FHPOR was obtained in the ranges of 1.453 to 1.459. The pH values were recorded between 4.058 to 4.57 for FHPO and 4.68 to 5.814 for FHPOR. In addition, the viscosity value also ranged from 73.635 to 88.415 cP for FHPO and 48.214 to 63.741 cP for FHPOR. Among the chemical parameters analyzed, peroxide values ranged from 10.167 to 14.578 meqO2/kg oil for FHPO and 6.463 to 9.8 meqO2/kg oil for FHPOR, iodine values from 57.34 to 53.54 g of I2/100g oil for FHPO, and from 45.55 to 50.465 g of I2/100g oil for FHPOR, acid values from 0.935 to 5.61mg KOH/g oil for FHPO and from 0.186 to 0.7922 mg KOH/g oil for FHPOR, saponification values from 204.5431 to 208.508 mg KOH/g oil for FHPO and 157.129 to 203.977 mg KOH/g oil for FHPOR, conjugated diene values from 3.079 to 4.374 % for FHPO and 0.2869 to 0.6432% for FHPOR. Statistical analyses using one-way ANOVA and Tukey’s test revealed significant differences (p < 0.05) across all studied physical and chemical parameters. GC-MS analysis also confirmed the removal of harmful chemicals such as alcohol, epoxide, ketone, and CDLA from FHPOR while oleic acid present, indicating that the oil had not decomposed. The level of heavy metal concentrations in FHPOR were found within the permissible limits (Pb: 0.01, Fe: 0.10, Cu: 0.10, Cd: 0.01, As: 0.01, Hg: 0.01) mg/100g, while FHPO exhibited higher levels (Pb: 0.10, Fe: 0.02, Cu: 0.11, Cd: 0.12, As: 0.11, Hg: 0.10) mg/100g. In conclusion, the incorporation of rosemary leaf powder into deep-frying practices significantly enhances the chemical profile of HPO by reducing toxicant chemicals and improving its oxidative stability. Generally, the present study showed the potential of rosemary as a natural additive for healthier cooking methods and improved oil quality