Knowledge of the appropriate learning techniques for the delivery of certain chemical concepts can be done an analyzing process of students abilities in multiple chemical representations. This research is intended to find out the students multiple representation ability in describing and explaining reaction rate concept. This research used descriptive research design by involving a group of subject. The test instrument contained of 15 two-tier multiple choices question. The results showed that 21.92% of students have been able to connect the three of chemical representation level which showed that the students have been complete understanding of the concept. In 25.55% of students tend to be able to interconnect at two representation levels which showed that the students have been able to draw a conclusion but experience a difficulty to see the reason. In 14.96% of students tend to understand the concept better at the submicroscopic representation level which showed that the students have not been able to draw a conclusion from the reason started and 37.56% of students have not been able either to comprehend or to connect the concept at three of representation levels. Based on grouping of answers to the ability interconnect the three levels of student representation, it can be seen that students are better able to solve problems with interconnection patterns starting from macroscopic to symbolic and submicroscopic.

The utilization of rice husk ash as an adsorbent has not been studied even though it has been used in various purposes. Therefore, it is important to research on the reaction rate absorption capacity of the adsorbent rice husk ash. By seen the chemical kinetics of rice husk, a study was identified the character of rice husk ash on its absorption capacity. The research was conducted by testing methods to two kinetics adsorption equations i.e Langmuir and Freundlich on changes in NaOH concentration. The experimental results show that process of absorption NaOH follows the Langmuir and Freundlich equations with r equal to 0.973. The suitable equation for determining the maximum adsorption capacity is to follow the Langmuir equation. The optimum concentration of NaOH adsorbed by active rice husk ash is 22,163 mg/L with an adsorption capacity of 4,433 mg/g.

Chemistry subjects are one of the subjects that students fear because many terms are used in learning them, so many strategies are made to understand them. Research has been done to see the improvement of metacognitive skills, conceptual mastery, and achievement of KKM value, student's chemical learning activity on chemical solubility calculation and solubility product through the problem solving learning model. The method used in this research is with data collection techniques through the test instrument description and metacognitive skills questionnaire in 2 cycles. Student metacognitive skill questionnaires data were analyzed by their mean score in descriptions and essay tests were analyzed by calculating the mean percent value of each cycle. The results showed that: (1) The mean percentage of metacognition skills through problem-solving abilities was 82.94% (high category). (2) the average value of student's chemical learning activity after following the learning by using problem solving learning model 4,71 (likert scale 1 s.d. 5) including high category. (3) The percentage of students who reach KKM score is 84.38%. This suggests that the problem-solving learning model can improve metacognitive skills while also increasing student activity in learning.

Inovasi model pembelajaran kooperatif-STAD terhadap hasil belajar telah banyak dilakukan namun demikian cenderung membutuhkan waktu yang relatif lama. Penelitian ini bertujuan untuk mengetahui penerapan model pembelajaran kooperatif-STAD dengan permainan word square terhadap motivasi dan hasil belajar siswa. Quasi-experiment ini menggunakan desain pretest-posttest control group. Sampel penelitian ini ditentukan dengan teknik purposive sampling yang terdiri dari dua kelas yaitu X TKJ 1 sebagai kelas eksperimen dan X TKJ 3 sebagai kelas kontrol. Instrumen penelitian menggunakan tes hasil belajar dan angket. Nilai signifikansi hasil uji MANOVA < 0,05 dan hasil uji deskriptif menyatakan terdapat peningkatan motivasi sebesar 15,13 dan hasil belajar sebesar 16,90. Oleh karena itu, terdapat pengaruh yang signifikan terhadap peningkatan motivasi dan hasil belajar siswa setelah diterapkannya model pembelajaran kooperatif-STAD dengan word square.

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