KNO3 is dried in temperature 105°C and dissolved in 1000 mL distilled water in volumetric flask).10 mL water samples (solutions in concentration range) with 1 mL sodium salicylate are evaporated in an evaporating dish, and cooled. 1 mL of concentrated H 2SO 4 was added so that way the entire residue dehumidified and allowed to stand for 10 minutes and transferred to a 50 ml volumetric flask. 7 mL NaOH was added and after cooling to room temperature, the volume was made to 50 mL with distilled water. After 10 minutes, the stain remains and