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钙镁的络合滴定,一般是以铬黑T或酸性铬蓝K-萘酚绿B为指示剂,用EDTA-Na_2络合滴定钙镁总量,同时以钙指示剂为指示剂,用EDTA-Na_2络合滴定钙,由两者之差算出镁量.但在汞精矿矿浆悬浮电解液中络合滴定钙镁总量时,发现滴定终点变化不明显,其原因主要是大量氯化钠存在的缘故,即大量氯化钠的存在,降低了钙镁与EDTA-Na_2形成络合物的稳定常数,且随氯化钠含量的增加,这种干扰明显增强,当氯化钠含量增至240g/L时,滴定终点就很难观察了.其二,氯化钠对指示剂还有破坏作用,当氯化钠达到半饱和(155g/l)时,钙镁与铬黑T或钙指示
Complexometric titration of calcium and magnesium, usually chromium black T or acid chrome blue K-naphthol green B as an indicator, with EDTA-Na 2 complex titration total calcium and magnesium, calcium indicators as indicators, with EDTA -Na_2 complexation titration of calcium, calculated by the difference between the amount of magnesium.But in the mercury concentrate pulp suspension electrolyte complex titration of total amount of calcium and magnesium, titration end point found no significant change, mainly due to a large number of sodium chloride The existence of a large number of sodium chloride, reducing the stability of calcium and magnesium with EDTA-Na 2 complex formation stability, and with the increase of sodium chloride content, this interference was significantly enhanced when the sodium chloride content increased 240g / L, titration of the end point is difficult to observe.Second, sodium chloride on the indicator also destructive effect, when the sodium chloride reached half-saturation (155g / l), calcium and magnesium and chromium black T or calcium instructions