<![CDATA[This research was aimed to develop apparatus of reaction heat determination, specified for reactions that produced gasses at constant pressure. Five stage of development on RD was applied in this research. Feasibility and functionality of the apparatus were justified by some validating and testing processes. For initial feasibility conducted design and apparatus validation has 100% percenttage result both of them. The functionality test of the apparatus was conducted and it was obtained 100%. Based on the preliminary field test, teachers and students gave judgment to feasibility of the apparatus with percentage of each them were 94.64% and 92%. Under these conditions, apparatus that has been developed was very feasible to be used.Penelitian ini bertujuan untuk mengembangkan alat penentuan kalor reaksi untuk reaksi-reaksi yang menghasilkan gas pada tekanan tetap. Lima tahap pada metode pengembangan dan penelitian telah digunakan pada penelitian ini. Adapun kelayakan dan keberfungsian alat dijustifikasi berdasarkan beberapa proses validasi dan pengujian. Untuk kelayakan alat awal dilakukan validasi desain dan alat dengan hasil persentase keduanya adalah 100% sehingga alat valid dan layak digunakan. Uji keberfungsian alat telah dilakukan dan diperoleh hasil 100%. Berdasarkan uji coba lapangan awal, guru dan siswa memberikan penilaian terhadap kelayakan alat guru dan siswa dengan persentase keduanya adalah 94,64% dan 92%. Berdasarkan hal tersebut, alat yang dikembangkan dinyatakan sangat layak digunakan.Kata kunci: alat, kalor reaksi, perubahan suhu, perubahan volume gas, tekanan tetap, termokimia]]>
