- 期刊
微分器輔助之自動酸鹼滴定
Differentiator-Assisted Automatic Acid-Base Titration
摘要
傳統的酸鹼滴定是以滴定管來進行滴定，在每加入一定量的滴定液後，便記錄所加入的體積以及pH-meter所測得之被滴定液的pH值，然後在整個滴定過程結束後，再將所記錄的pH值以及滴定液體積，在方格紙上逐點描繪出滴定曲線，或者將各點數據輸入電腦後由軟體程式來描繪出滴定曲線；然而此一傳統方法，不但煩瑣、費時，而且滴定當量點的決定往往亦不很容易，本實驗旨在示範，利用備蠕動泵、pH-meter及記錄器即可建立一套簡易的自動化酸鹼滴定系統，可即時記錄原始滴定曲線，使原本煩瑣、費時的酸鹼滴定實驗自動化；若再藉助簡易的電子電路：微分器及低通濾波器的輔助，則更可悶步記錄出滴定曲線的一次微分圖，使得滴定當量點的判定更快速且容易。本實驗並將微分器輔助之自動酸鹼滴定系統實際應用於測定未知樣品中Na_2CO_3的含量，發現該系統除再現性極佳外(RSD=0.38%, n=5)，分析結果與確認值間之相對誤差為-1.43%，可見本系統的準確性亦相當不錯，故不但可安排於分析化學教學實驗課程中，亦應可實際應用於例行性的酸鹼滴定及電位滴定分析中。
並列摘要
Normally buret and pH-meter are used in the acid-base titration. After each addition of titrant, the volume added and the corresponding pH reading are recorded. At the end of the titration, the titration curve is then plotted point by point manually or through computer, which is tedious and time-consuming. A differentiator-assisted automatic acid-base titration system is presented in this paper. Simply by use of a peristaltic pump, pH-meter and strip-chart recorder, the titration can proceed automatically and the titration curve can be recorded immediately. Furthermore, in couple with two simple Op Amp circuits: differentiator and low-pass filter, the first-derivative titration curve can be obtained simultaneously. This automatic titration system was applied for the determination of Na_2CO_3 in a reference material. The result is in good agreement with the certified value and the precision is also excellent.