【摘要】 蒸馏-中和滴定法测定氨氮时,采用甲基红-亚甲蓝混合指示剂确定滴定终点,但由于人眼分辨颜色的能力不同,判断出的终点往往有一定差异。以电位代替指示剂确定终点,以数字滴定仪代替滴定管,降低标准酸的浓度至0.01 mol/L,提出纯粹空白的概念,并最终通过试验找出了用盐酸滴定含有氨氮的硼酸吸收液的试验终点,即终点时溶液的pH值为5.8～5.9。电位滴定法摆脱了滴定操作对试验员的苛刻要求,而以数字信号代替颜色信号也使滴定终点更易辨别,测得的试验数据更加准确。更多还原

【Abstract】 Methylene bule-methyl red, as a mixed indicator, was used in distillation-neutralization titration determination of ammonia nitrogen. For the limit of visual sense, titration end could be different according to different person. Using potential as indicator to judge the titration end was proposed. Digital titrator was used to replace burette. A low concentration of hydrochloric acid 0.01 mol/L was used. The titration pH end was proved to be 5.8～5.9. Potentiometric titration could help lab employees get rid of difficult titration operation, making titration end easy to be judged, and more accurate results could be acquired.更多还原