Several misconceptions show up when learners answer questions on Chemical Equilibrium during examinations. Literature from other researchers shows similar trend of misconceptions (Johnstone, 2000; Morais, Paiva and Barros, 2007; Adesoji and Babatunde, 2008) for example, ‘apply pressure to the reactants’ (Johnstone, 2000). This shows that Chemistry has no meaning to these learners and they end up with misconceptions as they try to memorise facts in order to pass examinations. Learners are taught before writing these examinations, but how are they taught the concepts of Chemical Equilibrium? A descriptive approach was used on an exploratory survey conducted in Thohoyandou Cluster among Physical Science (Chemistry) FET band Educators. Cluster sampling of 40 educators from 18 randomly sampled schools responded to questionnaires. Five ‘well experienced’ educators who have been producing ‘good’ results at Grade 12 NSC examinations and two Physical Sciences subject advisors were interviewed. Using Spearman Brown Split-Half statistical method a 0,891 reliability coefficient was obtained. Research results show lack or under utilisation of laboratory equipment, teaching strategies which promote rote learning. Lack of confidence of educators due to deficiency in topic content knowledge and pedagogical skills which promote conceptual understanding were identified. Problem of English language leading to communication breakdown between educator-learners and between learner-subject leading to emergency of knowledge gaps in learners. Educators consider professional development through re-training and workshops on subject content matter and teaching strategies as the way forward to improve the quality of teaching. Topic specific PCK focusing on problem-solving strategy was recommended as a means to increasing educators’ efficiency in teaching and enhance learners’ comprehension and achievement in Physical Science. / Science and Technology Education / M. Sc. (Mathematics, Science and Technology Education (Chemistry Education))

Cette thèse décrit la Chimie Covalente Dynamique (CCD) des échanges imine/imine, Knoevenagel/imine et Knoevenagel/Knoevenagel. La L-proline est un excellent organocatalyseur pour la formation de Bibliothèques Covalentes Dynamiques (BCDs). Cependant, l’interconversion entre des dérivées Knoevenagel de l’acide diméthylbarbiturique et des imines se déroule rapidement sans catalyseur. Une nouvelle classe de CCD basée sur des échanges par substitutions nucléophiles (SN2/SN2’) entre des sels d’ammonium quaternaires et des amines tertiaires est développée, impliquant la catalyse par l’iodure. Les réactions d’échange entre des sels de pyridinium et un dérivé de pyridine génèrent des liquides ioniques dynamiques. Enfin, la sélection cinétique et thermodynamique de la formation d’imines dans la CCD est réalisée en solution aqueuse e ten solvant organique. / This thesis describes the dynamic covalent chemistry (DCC) of imine/imine, Knoevenagel/imine, and Knoevenagel/Knoevenagel exchange. L-proline is shown to be an excellent organocatalyst to accelerate the formation of dynamic covalent libraries (DCLs). The interconversion between Knoevenagel derivatives of dimethylbarbituric acid and imines is found to occur rapidly in the absence of catalyst. A new class of DCC based on nucleophilic substitution (SN2/SN2’) component exchange between quaternary ammonium salts and tertiary amines is developed, by the use of iodide as a catalyst. The exchange reactions between pyridinium salts and a pyridine derivative generate dynamic ionic liquids. Finally, kinetic and thermodynamic selection of imine formation in a DCC is perfomed in aqueous solution and organic solvent.

Several misconceptions show up when learners answer questions on Chemical Equilibrium during examinations. Literature from other researchers shows similar trend of misconceptions (Johnstone, 2000; Morais, Paiva and Barros, 2007; Adesoji and Babatunde, 2008) for example, ‘apply pressure to the reactants’ (Johnstone, 2000). This shows that Chemistry has no meaning to these learners and they end up with misconceptions as they try to memorise facts in order to pass examinations. Learners are taught before writing these examinations, but how are they taught the concepts of Chemical Equilibrium? A descriptive approach was used on an exploratory survey conducted in Thohoyandou Cluster among Physical Science (Chemistry) FET band Educators. Cluster sampling of 40 educators from 18 randomly sampled schools responded to questionnaires. Five ‘well experienced’ educators who have been producing ‘good’ results at Grade 12 NSC examinations and two Physical Sciences subject advisors were interviewed. Using Spearman Brown Split-Half statistical method a 0,891 reliability coefficient was obtained. Research results show lack or under utilisation of laboratory equipment, teaching strategies which promote rote learning. Lack of confidence of educators due to deficiency in topic content knowledge and pedagogical skills which promote conceptual understanding were identified. Problem of English language leading to communication breakdown between educator-learners and between learner-subject leading to emergency of knowledge gaps in learners. Educators consider professional development through re-training and workshops on subject content matter and teaching strategies as the way forward to improve the quality of teaching. Topic specific PCK focusing on problem-solving strategy was recommended as a means to increasing educators’ efficiency in teaching and enhance learners’ comprehension and achievement in Physical Science. / Science and Technology Education / M. Sc. (Mathematics, Science and Technology Education (Chemistry Education))