An understanding of the principles of complex equilibria and species distribution in different solutions is important in expounding and correlating the interaction of different ligands with different metal ions in complex formation. Therefore, acid-base equilibria involved in the formation of binary and ternary complexes of Co (II), Cu (II) and Pb (II) with methionine (Met) and uracil (Urc) have been determined by potentiometric titration technique. The stability constants of the complexes were evaluated at 35 ± 0.1°C and 0.02 M ionic strength (kept constant with NaNO3) in aqueous and organic-aqueous media. The species distribution in solutions as a function of pH was determined using the Hyss program. The stability of the ternary complexes relative to the corresponding binary complexes of the secondary ligand is measured in terms ΔlogK and % RS values. The ternary complexes are observed to be more stable than binary complexes in the media except for [CuMetUrc] ternary complex in organic-aqueous medium where the ternary complex is less stable than the binary complex of the uracil. The overall stability of the ternary complexes was higher in organic-aqueous system than aqueous system. The stability of the complexes was found to be correlated with the covalent index of the metal ions and Jahn Teller distortion. pH-studies of these systems revealed an increase in the concentrations of the ternary complexes with increase in pH. The formation of binary complexes was shown to be favoured in physiological pH range (3-7) while that of the ternary complexes is observed to be favoured in the pH range 5-10.
Self-efficacy as an independent variable has been identified as one of the most important factors that predict students’ continuous academic achievement. The role of self-efficacy on students’ academic achievement in chemistry has been examined among 150 students in two Oyo State schools of science. A questionnaire that contains 20 items on students’ academic self-efficacy was employed, while the academic achievement of the students was measured through an achievement test containing 20 chemistry questions. A descriptive survey research design was employed for the study. A Pearson correlation was utilized to determine the strength, as well as the positive or negative direction, of relationships between the variables. Linear regression was employed to determine the extent to which academic achievement is related to self-efficacy at the P < 0.05 statistical significance level. The analysis was carried out using R software version 3.6.2. The results of the analysis revealed a weak positive correlation between academic achievement and students’ self-efficacy. It was concluded that self-efficacy has a significant role in promoting academic achievement in chemistry. Therefore, students should develop themselves by cultivating the attitude of practicing everything they are being taught in chemistry every day. It is recommended that classroom activities be made very interesting and challenging for students’ efforts. Support and encouragement should be given to each student as he or she does his or her best to complete the assigned task.
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