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21st-century learning presents chemistry teachers with new challenges in teaching abstract chemistry concepts with various technologies that continue to develop. One of the media that can visualize abstract chemical concepts is Augmented Reality (AR). AR media developed in chemistry learning needs to be valid so that it can be used properly. Therefore, this study aims to examine the validity of the Android-based AR media developed. Four education practitioners carried out the validation as experts, and 13 students participated as respondents. The instrument used is a questionnaire with a Likert scale. The data obtained were analyzed quantitatively with the Rasch model using the facet software. The results of the analysis show that the Exact Agreements are 41.10%, and the Expected Agreements are 42.20%. The most challenging aspect to achieve is media design, while profit is the most easily agreed-upon aspect. Based on this assessment, in the development of augmented reality media, it is necessary to pay attention to display aspects and 3D objects suitable for viewing a material so that it is easier for users to understand the material.

ABSTRAKTujuan penelitian ini untuk Mengetahui pengaruh penambahan Ni terhadap nilai keasaman, dan Mengetahui kombinasi terbaik katalis dari nikel dan zeolit yang teraktivasi asam sebagai catalitic cracking pada proses pembuatan biodiesel dari minyak biji ketapang. Zeolit diaktivasi dengan menggunakan HCl 4 M. Pembuatan katalis Ni/Zeolit dengan merendam katalis zeolit ke dalam larutan Ni(NO3)2.6H2O dengan variasi konsentrasi 0 %, 5%, dan 10%.Karakterisasi ter-hadap katalis meliputi : XRD,SEM dan FTIR.Hasil Penelitian, data keasaman katalis di-peroleh bahwa penambahan logam Ni semakin meningkatkan nilai keasaman katalis. kombinasi Ni/Zeolit dengan kombinasi terbaikadalah pada 5% Ni/Zeolit. Kata kunci : biodisel, Ni/Zeolit, biji ketapang ABSTRACTThe purpose of this research are to know the effect of addition Ni on the acidity value of Ni/zeolite catalyst and to know the best combination nickel and Zeolit activated by acid as a catalyst of the cracking process during synthesis biodiesel from ketapang seed oil. The Ni/Zeolite catalysts were prepared by immersing the zeolite activated by HCl 4 M into Ni(NO3)2 solution with concentration variation of 0%, 5%, and 10%. The catalysts were characterized using XRD, SEM and FTIR. The results showed that the more Ni the more acidity value of the catalyst. The best quality of biodiesel was synthesized using combination catalysts of 5% Ni/Zeolite activated by acid.

Biodiesel is currently preferred for consumption and has been widely used as a substitute for diesel. This study aimed to determine the effect of various methanol-to-oil ratios in the esterification process and also the effect of hydrotalcite catalyst weight on the transesterification product. The catalyst was characterized with SEM, XRD, FTIR, and TG-DTG-DTA. The esterification process was operated at various oil-to-methanol ratios, i.e., 1:12-1:36 and the transesterification was performed using several catalyst weights, 0.5%-2.5%. The results showed that the optimum conditions of esterification were at the 1:30 molar ratio of oil-to-methanol, which decreased the amount of acid number by 95.75%, while the optimum condition of transesterification was at 1.5% catalyst weight. The characteristics of biodiesel using 0.5-2% hydrotalcite catalyst (acid number, total glycerol, free glycerol, ester levels, viscosity, density, oxidation stability) have met the Indonesian biodiesel standard of SNI-04-7182-2012.

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