電位滴定法的介紹：
電(dian)位(wei)滴(di)(di)定(ding)法是在(zai)滴(di)(di)定(ding)過程中(zhong)通(tong)過測量(liang)電(dian)位(wei)變化以確(que)定(ding)滴(di)(di)定(ding)終(zhong)點(dian)(dian)的(de)(de)(de)方(fang)法，和(he)直接電(dian)位(wei)法相比，電(dian)位(wei)滴(di)(di)定(ding)法不需(xu)要準(zhun)確(que)的(de)(de)(de)測量(liang)電(dian)極電(dian)位(wei)值，因此(ci)，溫(wen)度、液(ye)體接界電(dian)位(wei)的(de)(de)(de)影響并不重(zhong)要，其準(zhun)確(que)度優于(yu)直接電(dian)拉法，普通(tong)滴(di)(di)定(ding)法是依靠指(zhi)示劑(ji)顏色變化來指(zhi)示滴(di)(di)定(ding)終(zhong)點(dian)(dian)，如果待測溶液(ye)有顏色或(huo)渾濁(zhuo)時，終(zhong)點(dian)(dian)的(de)(de)(de)指(zhi)示就比較(jiao)困難，或(huo)者根本找不到(dao)合適的(de)(de)(de)指(zhi)示劑(ji)。電(dian)位(wei)滴(di)(di)定(ding)法是靠電(dian)極電(dian)位(wei)的(de)(de)(de)突躍來指(zhi)示滴(di)(di)定(ding)終(zhong)點(dian)(dian)。在(zai)滴(di)(di)定(ding)到(dao)達終(zhong)點(dian)(dian)前(qian)后，滴(di)(di)液(ye)中(zhong)的(de)(de)(de)待測離子(zi)濃度往往連續變化n個數量(liang)級，引起電(dian)位(wei)的(de)(de)(de)突躍，被測成分(fen)的(de)(de)(de)含量(liang)仍然通(tong)過消耗滴(di)(di)定(ding)劑(ji)的(de)(de)(de)量(liang)來計算。
使(shi)(shi)用(yong)不(bu)同的指(zhi)示(shi)(shi)電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)，電(dian)(dian)位滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)法可以(yi)(yi)進行酸堿滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)，氧化(hua)還原滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)，配合(he)滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)和沉(chen)淀滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)。酸堿滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)時(shi)使(shi)(shi)用(yong)PH玻璃電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)為指(zhi)示(shi)(shi)電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)，在(zai)氧化(hua)還原滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)中，可以(yi)(yi)從鉑電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)作指(zhi)示(shi)(shi)電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)。在(zai)配合(he)滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)中，若(ruo)用(yong)EDTA作滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)劑，可以(yi)(yi)用(yong)汞電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)作指(zhi)示(shi)(shi)電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)，在(zai)沉(chen)淀滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)中，若(ruo)用(yong)硝酸銀滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)鹵(lu)素離(li)子(zi)，可以(yi)(yi)用(yong)銀電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)作指(zhi)示(shi)(shi)電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)。在(zai)滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)過程中，隨著滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)劑的不(bu)斷加入，電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)電(dian)(dian)位E不(bu)斷發(fa)生變(bian)化(hua)，電(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)電(dian)(dian)位發(fa)生突躍時(shi)，說(shuo)明滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)到達(da)終點。用(yong)微分(fen)曲線(xian)比普通滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)曲線(xian)更容易確定(ding)(ding)(ding)滴(di)(di)(di)(di)(di)定(ding)(ding)(ding)終點。
電位滴(di)定(ding)的(de)步驟：
進(jin)行(xing)電位(wei)滴(di)定(ding)時，被測(ce)溶液中插(cha)入(ru)一個參(can)比電極(ji)，一個指示(shi)電極(ji)組成工作(zuo)電池(chi)。隨著滴(di)定(ding)劑(ji)的加入(ru)，由于(yu)發生(sheng)化(hua)學反應，被測(ce)離子(zi)濃度不斷變化(hua)，指示(shi)電極(ji)的電位(wei)也相(xiang)應地變化(hua)。在等當點附近發生(sheng)電位(wei)的突(tu)躍。因此測(ce)量工作(zuo)電池(chi)電動勢的變化(hua)，可確定(ding)滴(di)定(ding)終點。
電位滴定的(de)儀(yi)器(qi)：
電(dian)位滴定的(de)基本儀器(qi)裝置包括滴定管、滴定池、指示電(dian)極、參比電(dian)極、攪拌器(qi)，測電(dian)動勢的(de)儀器(qi)。
電位滴定(ding)法中滴定(ding)終點的確定(ding)：
用(yong)繪制電(dian)(dian)(dian)位確定曲(qu)線(xian)的(de)(de)方(fang)法。電(dian)(dian)(dian)位滴(di)定曲(qu)線(xian)即是隨著(zhu)滴(di)定的(de)(de)進行，電(dian)(dian)(dian)極電(dian)(dian)(dian)位值（電(dian)(dian)(dian)池電(dian)(dian)(dian)動勢(shi)）E對標(biao)準溶液(ye)(ye)的(de)(de)加(jia)(jia)入體積(ji)V作(zuo)圖的(de)(de)圖形。根據作(zuo)圖的(de)(de)方(fang)法不同，電(dian)(dian)(dian)位滴(di)定曲(qu)線(xian)有三種類型，E-V曲(qu)線(xian)，普通電(dian)(dian)(dian)位滴(di)定曲(qu)線(xian)，拐點(dian)(dian)(dian)e即為(wei)等當點(dian)(dian)(dian)。拐點(dian)(dian)(dian)的(de)(de)確定：作(zuo)兩(liang)條與滴(di)定曲(qu)線(xian)相切的(de)(de)45°傾斜的(de)(de)直線(xian)，等分線(xian)與曲(qu)線(xian)的(de)(de)交點(dian)(dian)(dian)即是拐點(dian)(dian)(dian)。Ee為(wei)等當點(dian)(dian)(dian)電(dian)(dian)(dian)位。Ve為(wei)等當點(dian)(dian)(dian)所需加(jia)(jia)的(de)(de)標(biao)準溶液(ye)(ye)的(de)(de)體積(ji)。電(dian)(dian)(dian)位突躍(yue)范圍(wei)和斜率越大，分析誤差(cha)就越小。
如果使(shi)用自(zi)動(dong)電位滴(di)(di)定(ding)儀，在(zai)滴(di)(di)定(ding)過程中可以自(zi)動(dong)繪出(chu)滴(di)(di)定(ding)曲(qu)線，自(zi)動(dong)找出(chu)滴(di)(di)定(ding)終點，自(zi)動(dong)給出(chu)體積，滴(di)(di)定(ding)快捷方(fang)便。
電位滴定(ding)法的特點(dian)和應用：
電位滴(di)定(ding)(ding)法比起用(yong)(yong)指示劑(ji)的容量分(fen)析法有(you)許(xu)多優越的地方，先可用(yong)(yong)于(yu)有(you)色或混濁的溶液的滴(di)定(ding)(ding)，使用(yong)(yong)指示劑(ji)是(shi)不行(xing)的；在沒(mei)有(you)或缺(que)乏指示劑(ji)的情況下，用(yong)(yong)此法解決；還(huan)可用(yong)(yong)于(yu)濃(nong)度(du)較稀的試(shi)液或滴(di)定(ding)(ding)反應進行(xing)不夠*的情況；靈(ling)敏度(du)和(he)(he)準(zhun)確度(du)高(gao)，并可實(shi)現自動化和(he)(he)連續測定(ding)(ding)。因此用(yong)(yong)途十分(fen)廣(guang)泛。按照滴(di)定(ding)(ding)反應的類型，電位滴(di)定(ding)(ding)可用(yong)(yong)于(yu)中和(he)(he)滴(di)定(ding)(ding)（酸(suan)堿滴(di)定(ding)(ding)）沉淀滴(di)定(ding)(ding)，絡合滴(di)定(ding)(ding)，氧化還(huan)原滴(di)定(ding)(ding)。
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