The implementation of SETS approach towards students achievement on the solubility material based on KKNI

The low students’ achievement, lack of variety of teaching methods on Basic Chemistry, lack of students’ engagement on teaching and learning process, misconception of Chemistry is difficult subject, and the changes of curriculum into KKNI on Industrial Revolution 4.0 that demand for the students are on the level 6 on the output based on the government legislation are the problems that need to be done on this study. This study aimed to find out the students’ achievement and response during the learning process on Basic Chemistry-Solubility and Solubility Product-class by using SETS approach based on KKNI. This is a quasi experiemental study through the distance learning. The technique of collecting the data was documentation and research instruments that consist of course outlines (RPS), students’ activity (observation sheet), and students’ work sheets that describe the activity with SETS method, pretest and post test, and the student’s questionnaire. The results showed that the implementation of SETS approach affects the students achievement thus there is enhancement on students achievement for the control and experimental class for 51.92% and the students response on the methods are 88%. The Concluded that there is an effect of Using SETS to improve student achievement and increasing student responses to learning.

The Effect of Media of Chemondro and Hybrid of Video Conference on Teaching Learning towards Students’ Self-efficacy and Students’ Achievement on the Subject of Solubility and Solubility Product

This research was conducted to analyze the effect of using the media of chemondro and hybrid video conferences in the teaching-learning toward students’ self-efficacy and students’ achievement on the subject of solubility and solubility product. The instruments of this research are the questionnaire and solubility and solubility product test. Thus, the research was set as quasi-experiment research using post-test only and non-equivalent control group design. By purposive sampling technique, the samples from 6 classes composed of 2 public senior high schools were selected. The classes were divided into 2 of hybrid learning with video conference and chemondro game (A), 2 classes of hybrid learning with video conference (B), and 2 classes of chemondro game (C). The corresponding data were collected on the basis of a self-efficacy learning questionnaire and a multiple-choice posttest of students' achievement in the subject of solubility and solubility product. The data were then tested by Manova. The results show that there was a significant difference in students’ self-efficacy and students’ chemistry cognitive achievement among the three classes, A, B, and C.

The Effectiveness of Online Learning in Solubility and Solubility Product Constant Materials on Students’ Analytical Thinking Skills

Analytical thinking skill is a part of higher order thinking skills. The ability to think analytically is very important for students who want to help solve problems and make decisions that can be applied in learning and life. This study aims to determine the improvement of students’ analytical thinking skills on the material solubility and solubility product which is carried out in online learning during the Covid-19 pandemic. This study uses a pre-experimental design, with the model The One Group Pretest – Posttest. The population of this study was students of class XI IPA SMAIT Insantama Bogor in the even semester of the 2019/2020 school year. The data were collected by using the thinking instrument skill test which was used in the form of an analytical thinking ability essay covering 3 indicators: distinguishing, organizing, and attributing. The results showed the dominance of students’ analytical thinking skills at the beginning of the period with the average majority (44%), and after treatment, increased in the very good category (74%). The N-gain score for the results of increasing students’ thinking skills is 0.70, which is in the high category. This study concludes that online learning in the material of solubility and solubility results proved to be effective in improving students’ analytical thinking skills during the pandemic

Solubility and Complex-Ion Equilibria

Solubility and Complex-Ion Equilibria broadens the previous chapter’s coverage of equilibria to include aqueous systems containing two or more solutes of slightly soluble ionic compounds and the formation of metal complexes in solution. Solubility equilibria which allow quantitative predictions of how much of a compound will dissolve under given conditions are covered. The meaning of the solubility product constant (K sp) and how to calculate it from molar solubility values is presented. Also discussed is determination of molar solubility from K sp. Calculations demonstrate how to predict the formation of a precipitate by comparing the ion product or solubility quotient (Q) with K sp. Formation constants of complex ions and calculations involving complex ion equilibria are explained.

Hydrogeochemistry of Fluorine in Groundwater in Humid Mountainous Areas: A Case Study at Xingguo County, Southern China

The understanding of F− concentration in groundwater in humid areas is limited although there are lots of research on high-fluoride groundwater in arid areas. In this paper, with controlling factors of F− concentrations in humid areas as the focus, 130 groundwater samples, obtained from four subsystems in Northwest Xingguo County, Jiangxi Province, China, were investigated to demonstrate the controlling factors of F− concentrations in humid areas. According to analytical results, the following hydrogeochemical characteristics of the fluorine in humid mountainous areas were determined: (1) F− concentration is positively correlated with total dissolved solids (TDS), Ca2+, HCO 3 − , and pH; (2) the groundwater features a high flow rate and low TDS; (3) the equilibrium constant of CaF2 is less than its solubility product constant, and the fluorine-bearing minerals in rocks are in a dissolved state; and (4) the dissolved fluoride-bearing minerals constitute the main sources of F− in the groundwater. Fluorine mainly comes from groundwater fluorine-bearing minerals in metamorphic rocks. Moreover, the low F− concentration in the groundwater mainly results from the fast flow rate of groundwater. Fluoride in groundwater has great potential hazards in humid areas.

The solubility product extends the buffering concept to heterotypic biomolecular condensates.

Biomolecular condensates are formed by liquid-liquid phase separation (LLPS) of multivalent molecules. LLPS from a single ('homotypic') constituent is governed by buffering: above a threshold, free monomer concentration is clamped, with all added molecules entering the condensed phase. However, both experiment and theory demonstrate that buffering fails for the concentration dependence of multi-component ('heterotypic') LLPS. Using network-free stochastic modeling, we demonstrate that LLPS can be described by the solubility product constant (Ksp): the product of free monomer concentrations, accounting for the ideal stoichiometries governed by the valencies, displays a threshold above which additional monomers are funneled into large clusters; this reduces to simple buffering for homotypic systems. The Ksp regulates the composition of the dilute phase for a wide range of valencies and stoichiometries. The role of Ksp is further supported by coarse-grained spatial particle simulations. Thus, the solubility product offers a general formulation for the concentration dependence of LLPS.

PRECIPITATION OF METAL HYDROXIDES FROM AQUEOUS SOLUTIONS AS A RESULT OF SPONTANEOUS CONDENSATION OF POLYNUCLEAR HYDROXOCOMPLEXES

Background. Generally, it is assumed that the formation of a solid phase (precipitate) happens when the activities of the involved ions would exceed those defined by the thermodynamic solubility product. However, in case of precipitation of metal hydroxides, this is a simplification, and the real pattern is more complicated, since metal ions form strong mono- and polynuclear hydroxocomplexes in a solution. Formation of such complexes, especially those with zero charge, should result in the deviation from the common solubility product rule. Objective. The aim of this paper is to develop a precipitation model, which takes into account the effect of the formation of the hydroxocomplexes on the solubility of a metal hydroxide. Eventually, this solubility includes the sum of the concentrations of metal ions, and all neutral, positively and negatively charged hydroxocomplexes involved in all equilibria in aqueous solution. Methods. We assume that formation of the solid precipitate is the result of spontaneous condensation of polynuclear neutral hydroxocomplexes when their concentrations in a solution exceed a certain critical value. These critical concentrations can be estimated from the consideration of all equilibria with the assumption that the equilibrium constants for the formation of neutral polynuclear complexes when their nuclearity increases by one are approximately equal and do not significantly depend on the size of the particle. Results. Using this approach, we developed the model, which predicts spontaneous condensation with formation of a precipitate. Also, we calculated the dependencies of pH-logCM for precipitation of various divalent cation hydroxides. It was shown that there exist minimal concentrations, below which no precipitates are formed at any pH value. Conclusions. Such approach also explains the nature of linear correlations between logarithms of solubility products and stability constants of neutral complexes described in literature. These results are important for the development and optimization of industrial wastewater treatment processes.