TRIS hydrochloride is a white crystalline powder that has a pKa of 8.08 at 25°C and pH range of 7.0 to 9.0 that coincides with the physiological pH of most living organisms because of which it is commonly used as a component of buffer solutions in biology, biochemistry and molecular biology applications. Tris salts are also used for crystallization of proteins at various pH values. Neither Tris base nor Tris hydrochloride by itself provide adequate buffering capacity. Generally the two need to be mixed together to provide a buffer with pH between 7 and 9 to provide adequate buffering.