PENGARUH WAKTU TERHADAP PENURUNAN KESADAHAN AIR SUMUR DIII TEKNIK KIMIA DENGAN METODE KOMPLEKSOMETRI MENGGUNAKAN DEMINERALIZER (The Influence of Time to Herdness Reduction of DIII chemical engineering’s Well Water With Kompleksometri Method By Using Demineralizer)

Water is a natural resource that is abundant and the basic needs of daily living things in this world that can not be separated. Source - the water source is sea water, atmospheric water, surface water, river water, swamp water, groundwater and springs. Hard water is water that contains salts of calcium and magnesium, or water that is difficult to wash. Calcium and magnesium compounds breaksi with soap to form a precipitate and prevent foam in water. Hard water hardness is divided into 2 temporary and permanent. Demineralised water is a process of absorption of the mineral content of ions in the water. Water demineralization process proceeds used for a variety of needs, especially for industry. Demineralized tool consists of three parts, namely cation tank, tank anion and mixed bed. The method used in the hardness test is complexometric titration is a titration based on the formation of complexes between cationic compounds with complex forming agent. Keywords: water, demineralized, complexometr