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Chemical Equations are valuable tool for helping students comprehend chemical reactions, as these reactions are intricately connected to human activities. The analysis of blood and tissue samples, the dating of fossils, the investigation of antiquity, and the detection and characterization of planets are a few of these chemical reactions. In order to understand more about how well students understood chemical equations using the coloured stick model and pictorial analogies, this study employed a quasi-experimental methodology. This research design, sought to establish a cause-and-effect relationship because groups were not randomly assigned. Two sections of Grade 10 students participated in this study as respondents, and they were selected depending on their availability and willingness to participate in the study. It was discovered that the difference in scores gained by the two groups is statistically significant. The computed absolute value of t (-4.09) is higher than the t-critical (2.08) with a p-value of 0.00, lower than the level of significance of 0.05, which proved that the pictorial analogy group performs better than the coloured stick group. It is recommended that, whenever applicable, the model be repeated in a variety of chemistry topics and courses that frequently use numerical presentation.

The development of studies of Chemical solutions occurred with two distinct concepts, the XIX century concept, and the XX century concept. XIX century concept was created before the Arrhenius’ electrolytic theory and it did not consider the real chemical species in solution. The differences between these concepts can seem subtle at a glance, but some examples are shown to clarify them, as well as the problems with use the XIX century concept. The examples involve differences in chemical equations, Henderson-Hasselbach Equation, Arrhenius’ Ionization degree, Acid-base and solubility equilibria.

The aim of this research was to investigate whether pupils aged 13, at the end of their first year of studying chemistry, are capable of perceiving the macroscopic and the submicroscopic level of the previously learned contents on chemical reactions, and whether they relate them to the chemical equations (the symbolic representation). Another aim was to establish how much demonstration experiments contribute to a better linking of the mentioned levels. The research featured 69 pupils of the seventh grade from three primary schools. The pre-test was conducted, following which experiments were demonstrated, and the post- -testing was carried out in the end. After the intervention, a total of 12 pupils were interviewed about which aspects of chemical reactions they thought of based on the chemical equations. A statistically significant difference in two out of five requirements of the post-test, compared to the pre-test, indicate that the demonstration experiments may contribute to a better linking of three levels of representing chemical reactions. However, when one compares the pupils’ answers in the test and in the interview, it can be observed that the correct answers in the test are not always based on understanding the concepts in connection with the chemical reaction. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 179048: The Theory and Practice of Science in Society: Multidisciplinary, Educational and Intergenerational Perspectives]

Abstract This paper reports on the development of a simple organized approach for balancing a given nuclear equation in which all the reactants and products appear explicitly. A novel general algorithm for finding the balanced form of a nuclear equation has been offered for the said purpose. It has been found that, in addition to having the physically admissible balanced form of a nuclear equation, the present scheme gives birth to a lot of other independent balanced forms of the same nuclear equation, each of which, though theoretically possible, corresponds to unphysical equations. In addition to having novelty, the present scheme is expected to have educational value and it might be of didactic interest to physics students.