1)總體原則
當dang要yao求qiu得de到dao最zui高gao準zhun確que度du時shi,應ying盡jin可ke能neng按an校xiao準zhun時shi的de條tiao件jian來lai操cao作zuo,並bing要yao求qiu用yong分fen度du誤wu差cha的de校xiao準zhun值zhi。使shi用yong前qian量liang器qi應ying清qing洗xi幹gan淨jing,如ru果guo校xiao準zhun時shi發fa現xian示shi值zhi容rong量liang有you偏pian差cha時shi,應ying做zuo適shi當dang修xiu正zheng。
2)容量瓶
如果使用容量瓶定容水溶液,則用蒸餾水清洗後可不必幹燥。稀釋水溶液的方法推薦如下:badairongjiedewuzhijiarushiliangdeshuizaishaobeizhongjinxingrongjie,zaibiyaoshikeshidujiarebingyaodongshizhirongjie,rongjiehouzhuanyidaorongliangpingzhong,bingyongzhengliushuiduocirunxishaobeibingjiangxiyezhuanzhirongliangpingzhong。jiezhejiashuishiyemianshengdaokeduxianjilimiyixia。gaishangpingsaihunhehou,yongxipingshuiliuchongxishiyemianshengdaokeduxianyixia1cm處,打開容量瓶塞,靜置2 min,讓瓶頸的液體瀝下,要使溶液重新達到室溫可以蓋上瓶塞多等待一定些時間。最後從刻度線以下1cm 以內的一點沿著瓶頸流下一定的水,使彎液麵的最低點調定在刻度線上。蓋上瓶塞搖動顛倒容量瓶,使溶液均勻備用。
3)量筒和量杯
量筒經清洗和幹燥後,充以待測液體至標稱容量刻線或所需的刻線上幾毫米,接著用吸管將多餘的液體吸出。
4)滴定管
滴定管(包括旋塞閥和流液口)用yong蒸zheng餾liu水shui清qing洗xi後hou,再zai用yong待dai用yong的de試shi液ye衝chong洗xi三san次ci。如ru果guo滴di定ding管guan尺chi寸cun不bu夠gou大da,其qi頂ding部bu插cha不bu進jin溫wen度du計ji用yong於yu觀guan測ce液ye體ti溫wen度du,可ke設she置zhi一yi根gen足zu以yi容rong納na溫wen度du計ji的de普pu通tong玻bo璃li試shi管guan夾jia在zai滴di定ding管guan旁pang邊bian。
將jiang夾jia在zai垂chui直zhi位wei置zhi的de滴di定ding管guan充chong水shui至zhi零ling線xian以yi上shang幾ji毫hao米mi,如ru果guo管guan壁bi沾zhan濕shi,則ze在zai調tiao定ding零ling線xian以yi前qian應ying有you充chong分fen的de瀝li液ye時shi間jian,為wei了le排pai除chu旋xuan塞sai閥fa和he流liu液ye口kou間jian氣qi泡pao,在zai調tiao定ding零ling線xian之zhi前qian應ying從cong流liu液ye口kou排pai放fang一yi些xie液ye體ti再zai注zhu液ye。
流(liu)出(chu)時(shi)間(jian)是(shi)指(zhi)當(dang)旋(xuan)塞(sai)閥(fa)全(quan)開(kai)時(shi)液(ye)體(ti)從(cong)零(ling)線(xian)至(zhi)標(biao)稱(cheng)容(rong)量(liang)自(zi)由(you)流(liu)出(chu)所(suo)用(yong)的(de)時(shi)間(jian)。為(wei)了(le)得(de)到(dao)最(zui)佳(jia)準(zhun)確(que)度(du),應(ying)使(shi)用(yong)分(fen)度(du)修(xiu)正(zheng)值(zhi)。在(zai)放(fang)液(ye)時(shi)旋(xuan)塞(sai)閥(fa)應(ying)全(quan)開(kai),流(liu)液(ye)口(kou)不(bu)得(de)與(yu)接(jie)收(shou)容(rong)器(qi)及(ji)液(ye)麵(mian)接(jie)觸(chu)。因(yin)此(ci),對(dui)滴(di)定(ding)管(guan)來(lai)說(shuo),最(zui)好(hao)能(neng)估(gu)算(suan)出(chu)試(shi)樣(yang)需(xu)耗(hao)用(yong)多(duo)少(shao)毫(hao)升(sheng)溶(rong)液(ye)方(fang)可(ke)到(dao)達(da)終(zhong)點(dian),如(ru)果(guo)有(you)足(zu)夠(gou)的(de)試(shi)樣(yang)可(ke)進(jin)行(xing)一(yi)次(ci)預(yu)先(xian)的(de)滴(di)定(ding)來(lai)得(de)到(dao)這(zhe)一(yi)點(dian)。如(ru)果(guo)不(bu)能(neng)這(zhe)樣(yang)做(zuo),隻(zhi)要(yao)滴(di)定(ding)時(shi)間(jian)不(bu)超(chao)過(guo)規(gui)定(ding)流(liu)出(chu)時(shi)間(jian)60s,則在容量允差為±tmL 時,所產生的誤差一般小於±tm L。如ru果guo規gui定ding了le等deng待dai時shi間jian則ze為wei旋xuan塞sai閥fa關guan閉bi後hou與yu最zui後hou讀du數shu之zhi前qian的de那na段duan時shi間jian,通tong常chang不bu得de在zai滴di定ding進jin行xing時shi觀guan測ce等deng待dai時shi何he,因yin為wei達da到dao滴di定ding終zhong點dian的de時shi間jian一yi般ban比bi規gui定ding的de等deng待dai時shi間jian長chang。
上shang述shu使shi用yong情qing況kuang適shi用yong於yu粘zhan度du與yu水shui相xiang似si的de透tou明ming液ye體ti,特te別bie粘zhan稠chou的de液ye體ti不bu能neng準zhun確que而er方fang便bian地di使shi用yong,因yin為wei這zhe樣yang會hui在zai管guan壁bi上shang留liu下xia大da量liang的de粘zhan液ye,而er且qie流liu速su很hen慢man,但dan是shi通tong常chang用yong於yu容rong量liang分fen析xi的de稀xi釋shi水shui溶rong液ye是shi適shi用yong的de,而er且qie無wu明ming顯xian的de誤wu差cha。例li如ru:1mol/L 的溶液產生的誤差小於A 級的允差。而0.1mol/L 的(de)溶(rong)液(ye)則(ze)產(chan)生(sheng)的(de)誤(wu)差(cha)相(xiang)應(ying)更(geng)小(xiao)。當(dang)使(shi)用(yong)非(fei)水(shui)液(ye)體(ti)時(shi)準(zhun)確(que)度(du)也(ye)會(hui)降(jiang)低(di),因(yin)為(wei)它(ta)們(men)的(de)表(biao)麵(mian)張(zhang)力(li)與(yu)水(shui)的(de)表(biao)麵(mian)張(zhang)力(li)相(xiang)差(cha)很(hen)大(da)。對(dui)於(yu)彎(wan)液(ye)麵(mian)底(di)部(bu)可(ke)見(jian)度(du)較(jiao)差(cha)的(de)液(ye)體(ti),可(ke)在(zai)彎(wan)液(ye)麵(mian)上(shang)邊(bian)緣(yuan)讀(du)數(shu),但(dan)比(bi)在(zai)彎(wan)液(ye)麵(mian)最(zui)低(di)點(dian)觀(guan)測(ce)到(dao)的(de)準(zhun)確(que)度(du)要(yao)差(cha)些(xie)。
5)量出式吸量管
吸xi量liang管guan用yong蒸zheng餾liu水shui清qing洗xi之zhi後hou,再zai用yong待dai用yong液ye體ti衝chong洗xi。吸xi量liang管guan吸xi取qu液ye體ti至zhi零ling標biao線xian以yi上shang或huo所suo需xu刻ke度du線xian以yi上shang幾ji毫hao米mi。建jian議yi使shi用yong能neng使shi待dai測ce液ye體ti自zi由you流liu動dong的de吸xi具ju,如ru吸xi球qiu等deng。
為(wei)了(le)得(de)到(dao)正(zheng)確(que)的(de)量(liang)出(chu)容(rong)量(liang),吸(xi)量(liang)管(guan)應(ying)按(an)其(qi)產(chan)品(pin)標(biao)準(zhun)中(zhong)有(you)關(guan)容(rong)量(liang)定(ding)義(yi)所(suo)述(shu)的(de)方(fang)法(fa)操(cao)作(zuo)。吸(xi)量(liang)管(guan)與(yu)接(jie)收(shou)容(rong)器(qi)脫(tuo)離(li)之(zhi)前(qian),應(ying)遵(zun)守(shou)規(gui)定(ding)的(de)等(deng)待(dai)時(shi)間(jian)。通(tong)常(chang)吸(xi)量(liang)管(guan)掛(gua)壁(bi)液(ye)體(ti)流(liu)至(zhi)流(liu)液(ye)口(kou)的(de)等(deng)待(dai)時(shi)間(jian)規(gui)定(ding)3s已(yi)足(zu)夠(gou)了(le),而(er)且(qie)不(bu)需(xu)要(yao)準(zhun)確(que)測(ce)定(ding)。一(yi)旦(dan)確(que)定(ding)彎(wan)液(ye)麵(mian)達(da)到(dao)流(liu)液(ye)口(kou)並(bing)趨(qu)於(yu)靜(jing)止(zhi),吸(xi)量(liang)管(guan)即(ji)可(ke)與(yu)接(jie)收(shou)容(rong)器(qi)脫(tuo)離(li)接(jie)觸(chu)。留(liu)在(zai)流(liu)液(ye)口(kou)的(de)餘(yu)液(ye)不(bu)得(de)排(pai)出(chu),而(er)“吹出”shixiliangguanzeyingchuichuqizuihouyuyezuoweiliangchurongliangdeyibufen。yudidingguanyiyang,feichangzhanchoudeyetibunengfangbianhezhunquedixiqu。tongchangyongyurongliangfenxidexishishuirongyeshishiyongde,erqiewumingxianwucha。
6)量入式吸量管
用(yong)蒸(zheng)餾(liu)水(shui)清(qing)洗(xi)之(zhi)後(hou)進(jin)行(xing)幹(gan)燥(zao)或(huo)用(yong)待(dai)測(ce)溶(rong)液(ye)衝(chong)洗(xi)三(san)次(ci)。吸(xi)取(qu)液(ye)體(ti)至(zhi)零(ling)標(biao)線(xian)以(yi)上(shang)或(huo)所(suo)需(xu)刻(ke)度(du)線(xian)以(yi)上(shang)。為(wei)了(le)得(de)到(dao)正(zheng)確(que)的(de)量(liang)入(ru)容(rong)量(liang),吸(xi)量(liang)管(guan)應(ying)按(an)有(you)關(guan)容(rong)量(liang)定(ding)義(yi)所(suo)述(shu)方(fang)法(fa)操(cao)作(zuo)。
小結
本ben文wen所suo述shu的de操cao作zuo主zhu要yao是shi需xu要yao和he校xiao準zhun計ji量liang玻bo璃li容rong器qi時shi保bao持chi一yi致zhi,一yi般ban來lai說shuo操cao作zuo和he校xiao準zhun時shi保bao持chi一yi致zhi會hui更geng大da程cheng度du保bao證zheng準zhun確que度du和he校xiao準zhun一yi致zhi的de狀zhuang態tai。
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