第二十四章容量分析

1、Lesson 24. Volumetric Analysis學(xué)習(xí)詞匯學(xué)習(xí)詞匯常用的化學(xué)實驗儀器常用的化學(xué)實驗儀器3. 練習(xí)全文翻譯練習(xí)全文翻譯 volumetric 體積的，容量的體積的，容量的unknown test sample未知試樣未知試樣coincide 符合，一致符合，一致stoichiometric 化學(xué)計量的化學(xué)計量的endpoint 終點(diǎn)終點(diǎn)titration 滴定滴定molarity 摩爾濃度摩爾濃度normality 當(dāng)量濃度當(dāng)量濃度equivalent 當(dāng)量當(dāng)量gram molecular weight 克分子克分子量量mole weight 分子量分子量curve 曲

2、線曲線graph 曲線圖曲線圖representation 代表，象征代表，象征 marking 刻度，條紋，標(biāo)志刻度，條紋，標(biāo)志burette 滴定管滴定管tap water 自來水自來水rinse 沖洗沖洗drain 依次排出依次排出vinegar 醋醋methyl red 甲基紅甲基紅record 記錄記錄pH meter pH計計frost 霜，霜化霜，霜化render 致使，使成為致使，使成為simultaneously 同時地同時地in the case of 在在情況下，要是情況下，要是bring about 導(dǎo)致，引起導(dǎo)致，引起mol(e)- 摩爾，分子 molarity n.

3、 摩爾濃度摩爾濃度 molecule n. 分子分子 molecular adj. 分子的分子的nor- 正，正常，降，去甲 normal adj. 正常的，普通的正常的，普通的 normalize v.使正?；拐；?normality n. 當(dāng)量濃度當(dāng)量濃度 norbornene n. 降冰片烯降冰片烯 noradrenaline n. 去甲腎上腺素去甲腎上腺素前后綴前后綴坩堝坩堝crucible蒸發(fā)皿蒸發(fā)皿evaporation dish三腳架tripod泥三角Clay trianglebeaker燒瓶圓底燒瓶圓底燒瓶平底燒瓶平底燒瓶round bottom flaskflat bot

4、tom flaskFlorence flask燒瓶兩口燒瓶兩口燒瓶2-neck Boiling flask 集氣瓶gas-jarAlcohol burner wire gauzegas-jarround bottom flaskStopper Stopper Ring stand with ring廣口瓶Wide mouth bottle滴瓶Dropping bottle 溫度計100 mL10 mL量筒Thermometer graduated cylinderMeasuring cylinder 注意區(qū)別BuretteAcid buretteBase burette容量瓶容量瓶容量瓶vol

5、umetric flaskBurette clampBurette standAcid buretteBase buretteBurette stand with double clampsHolding two burettevolumetric flaskErlenmeyer flask Conical flask分液漏斗separating funnelBuchner funnelAllihn type condenserWest type condenserserpentine condenser adapterDistilling headTest tubeTest tube rac

6、kTest tube brushtest tube clamp pipette pipette triangular flask Plastic squeeze bottleRubber pipette bulbChemical analyses can be made by determining how much of a solution of known concentration is needed to react fully with an unknown test sample. The method is generally referred to as volumetric

7、 analysis and consists of titrating the unknown solution with the one of known concentration (a standard solution). By titration, you can determine exactly how much of a reagent is required to bring about complete reaction of the test solution. F 化學(xué)分析的一般通過測定一已知濃度的溶液與未知試樣完全反應(yīng)的關(guān)化學(xué)分析的一般通過測定一已知濃度的溶液與未知試

8、樣完全反應(yīng)的關(guān)系來進(jìn)行，該方法一般也稱為容量分析，方式是用已知濃度的標(biāo)準(zhǔn)溶液系來進(jìn)行，該方法一般也稱為容量分析，方式是用已知濃度的標(biāo)準(zhǔn)溶液來滴定未知溶液。通過滴定分析，你可以測定與試樣完全反應(yīng)的標(biāo)準(zhǔn)溶來滴定未知溶液。通過滴定分析，你可以測定與試樣完全反應(yīng)的標(biāo)準(zhǔn)溶液的消耗量。液的消耗量。General principles 通用原理通用原理Usually, completion of the reaction is indicated by a sudden, visible change in the reaction system that coincides with the stoich

9、iometric relationship between moles or equivalents of-the reagent solution and the reactant in the test solution. A drop or two of an appropriate indicator solution produces a color change at the point where the reaction is complete-referred to as the endpoint.F 一般來說，反應(yīng)體系出現(xiàn)可見的突變表明反應(yīng)已完全進(jìn)行，此時滴定劑與一般來說，

10、反應(yīng)體系出現(xiàn)可見的突變表明反應(yīng)已完全進(jìn)行，此時滴定劑與被滴定物質(zhì)的摩爾數(shù)或當(dāng)量滿足一定的化學(xué)計量關(guān)系。被滴定物質(zhì)的摩爾數(shù)或當(dāng)量滿足一定的化學(xué)計量關(guān)系。12滴合適的指示劑滴合適的指示劑可在某個時刻產(chǎn)生顏色突變，此時滴定反應(yīng)完全進(jìn)行，稱為滴定終點(diǎn)?？稍谀硞€時刻產(chǎn)生顏色突變，此時滴定反應(yīng)完全進(jìn)行，稱為滴定終點(diǎn)。Molarity is the number of moles (gram-molecular weights)of substance per liter of solution. The mole weight of sulfuric acid is 98.08 g, and theref

11、ore, 1 mole of H2SO4 contains 98.08 g. If 49.04 g are diluted to 1 liter then the concentration is 0.49 or 0.5M. In the case of hydrochloric acid, HCl, a 1 M solution is prepared by taking 36.465 g of HC1 and diluting to 1 liter. The procedure is the same for bases. F 摩爾濃度是每升溶液中含有某物質(zhì)的摩爾數(shù)（或克分子量）。硫酸的克

12、分摩爾濃度是每升溶液中含有某物質(zhì)的摩爾數(shù)（或克分子量）。硫酸的克分子量為子量為98.08 g，因此，因此1 M的硫酸溶液含有的硫酸溶液含有98.08 g的硫酸；如果的硫酸；如果49.04 g的硫酸的硫酸稀釋到稀釋到1 L溶液，那硫酸的濃度為溶液，那硫酸的濃度為0.49 或或0.5 M。以鹽酸為例，。以鹽酸為例，1 M鹽酸由鹽酸由1 M HCl溶于溶于1 L水制得，堿的情況亦是如此。水制得，堿的情況亦是如此。Normality is the number of equivalent weights of substance per liter of solution. The equivalen

13、t weight of an acid is the weight of that acid capable of furnishing 1 mole of protons (H+), and the equivalent weight of a base is the weight of base capable of receiving 1 mole of protons. The equivalent weight of H2SO4 is 98.08g/2 or 49.04 g. Therefore, a normal solution (N)of H2SO4 contains 49.0

14、4g per liter.F 當(dāng)量濃度是一升溶液中某物質(zhì)的當(dāng)量數(shù)，酸的當(dāng)量指能提供當(dāng)量濃度是一升溶液中某物質(zhì)的當(dāng)量數(shù)，酸的當(dāng)量指能提供1 摩爾氫離子摩爾氫離子的酸的質(zhì)量，堿的當(dāng)量是接受的酸的質(zhì)量，堿的當(dāng)量是接受1摩爾氫離子的堿的質(zhì)量。硫酸的當(dāng)量為摩爾氫離子的堿的質(zhì)量。硫酸的當(dāng)量為98.08 g除以除以2或或49.04 g，因此一當(dāng)量的硫酸溶液每升含有，因此一當(dāng)量的硫酸溶液每升含有49.04 g硫酸。硫酸。The normality of an acid or base of unknown concentration may be determined by titration. The ad

15、vantage of using normality rather than molarity is that equal volumes of solutions of equal normalities have identical capacities for neutralization, because they contain the same number of equivalent weights. F 未知濃度的酸未知濃度的酸/堿的當(dāng)量濃度可用滴定分析測定，當(dāng)量濃度優(yōu)于摩爾濃度堿的當(dāng)量濃度可用滴定分析測定，當(dāng)量濃度優(yōu)于摩爾濃度在于相同體積的等當(dāng)量溶液具有相同的中和能力，因為兩

16、者具有相同的當(dāng)量在于相同體積的等當(dāng)量溶液具有相同的中和能力，因為兩者具有相同的當(dāng)量數(shù)。數(shù)。In a titration, we compare equivalent weights of acid and base. The number of equivalents of acid is equal to the product of the volume of the acid solution and its normality. The number of equivalents of base is the product of the volume of the base solu

17、tion and its normality. Neutralization has taken place when the number of equivalents of acid is equal to the number of equivalents of base.F 滴定時我們會比較酸與堿的當(dāng)量。酸的當(dāng)量數(shù)等于酸的體積乘以它的當(dāng)量滴定時我們會比較酸與堿的當(dāng)量。酸的當(dāng)量數(shù)等于酸的體積乘以它的當(dāng)量濃度，堿的當(dāng)量數(shù)等于堿的體積乘以當(dāng)量濃度。當(dāng)酸與堿的當(dāng)量數(shù)相等時，濃度，堿的當(dāng)量數(shù)等于堿的體積乘以當(dāng)量濃度。當(dāng)酸與堿的當(dāng)量數(shù)相等時，中和反應(yīng)發(fā)生。中和反應(yīng)發(fā)生。Care must be e

18、xercised throughout the titration procedure. The burette should be thoroughly cleaned with soap and water, rinsed with tap water, and finally, rinsed with distilled water. Just before use, the burette should be rinsed with two 5-ml portions of the solution to be used in the burette. This is done by

19、holding the burette in a semi-horizontal position and rolling the solution around the entire inner surface. Allow the final rinsing to drain through the tip. F 滴定過程要十分小心，滴定管必須用肥皂和水完全洗凈，再依次用自來水滴定過程要十分小心，滴定管必須用肥皂和水完全洗凈，再依次用自來水和蒸餾水沖洗。使用前滴定管還要用和蒸餾水沖洗。使用前滴定管還要用5-mL的使用溶液清洗兩遍，其過程為：的使用溶液清洗兩遍，其過程為：將滴定管半平放，轉(zhuǎn)動

20、滴定管使管內(nèi)溶液與內(nèi)表面充分浸潤，然后從滴定管將滴定管半平放，轉(zhuǎn)動滴定管使管內(nèi)溶液與內(nèi)表面充分浸潤，然后從滴定管尖嘴放掉潤洗溶液。尖嘴放掉潤洗溶液。Procedure 步驟步驟Fill the burette to a point above the top marking and allow the solution to run out until the bottom of the meniscus is just at the top marking of the burette. The burette tip must be completely filled to deliver

21、 the volume measured. F 在滴定管內(nèi)引入溶液到高于頂端刻度線以上，然后從尖嘴處放出溶液直至在滴定管內(nèi)引入溶液到高于頂端刻度線以上，然后從尖嘴處放出溶液直至凹液面與頂端刻線齊平，滴定管尖嘴要完全充滿溶液以放出準(zhǔn)確的體積。凹液面與頂端刻線齊平，滴定管尖嘴要完全充滿溶液以放出準(zhǔn)確的體積。In addition, the burette must be cleaned thoroughly after use because sodium hydroxide and other types of solutions will eventually frost the glass

22、and render an expensive piece of equipment useless. F 此外滴定管在使用后也要完全洗凈，因為氫氧化鈉和其它類型的試劑會腐蝕此外滴定管在使用后也要完全洗凈，因為氫氧化鈉和其它類型的試劑會腐蝕玻璃，導(dǎo)致滴定管的某個昂貴組件無法使用。玻璃，導(dǎo)致滴定管的某個昂貴組件無法使用。1. Titration of Vinegar Measure 50 ml of vinegar with a pipette and pour into a 250-ml beaker. Add 2 drops of phenolphthalein indicator. Fil

23、l a burette with a 1 N solution of sodium hydroxide (NaOH) and draw out the excess as described above. From the burette add NaOH to the beaker of vinegar until 1 drop of NaOH produces a pale pink color in the solution. Maintain constant stirring. The appearance of pink tells you that the acid has be

24、en neutralized by the base and there is now 1 drop of excess base which has turned the indicator. Read the burette and record this reading as the volume of base used to neutralize the acid. F 1. 食醋的滴定：用吸液管量取食醋的滴定：用吸液管量取50mL的食醋到的食醋到250 mL燒杯，加入兩滴酚酞指示燒杯，加入兩滴酚酞指示劑，將劑，將1當(dāng)量的氫氧化鈉濃度裝入堿式滴定管，并按上述操作放出多余的溶液。當(dāng)量的

25、氫氧化鈉濃度裝入堿式滴定管，并按上述操作放出多余的溶液。從滴定管將氫氧化鈉加入到燒杯與食醋反應(yīng)，直至過量的一滴氫氧化鈉使酚酞產(chǎn)從滴定管將氫氧化鈉加入到燒杯與食醋反應(yīng)，直至過量的一滴氫氧化鈉使酚酞產(chǎn)生淺粉色，滴定過程中要一直振蕩溶液。粉色的出現(xiàn)表明酸已完全被堿中和，過生淺粉色，滴定過程中要一直振蕩溶液。粉色的出現(xiàn)表明酸已完全被堿中和，過量的一滴氫氧化鈉與指示劑反應(yīng)使其變色。讀出滴定管的刻度，記下中和食醋的量的一滴氫氧化鈉與指示劑反應(yīng)使其變色。讀出滴定管的刻度，記下中和食醋的氫氧化鈉的體積。氫氧化鈉的體積。According to the equation：NaOH + CH3COOH Na+ +

26、 CH3COO- + H2OOne molecule of NaOH neutralizes one molecule of acetic acid, or one gram-molecular weight of NaOH neutralizes one gram-molecular weight of acetic acid. Calculate the amount of acetic acid present in the vinegar. Report this amount as the percentage of acetic acid. F 根據(jù)反應(yīng)式根據(jù)反應(yīng)式NaOH + C

27、H3COOH Na+ + CH3COO- + H2O，一分子氫氧化鈉，一分子氫氧化鈉中和一分子的乙酸，或一克分子量的氫氧化鈉中和一克分子量的乙酸中和一分子的乙酸，或一克分子量的氫氧化鈉中和一克分子量的乙酸 。然后計。然后計算出醋中乙酸的含量，用乙酸的百分比來表示。算出醋中乙酸的含量，用乙酸的百分比來表示。2. Standard Titration Curve If a pH meter is available, repeat the above process using a pH meter for constantly determining the pH. When the endpo

28、int is reached, continue adding the base to expand the curve further. Make a graph for this titration. F 2. 標(biāo)準(zhǔn)滴定曲線：如果有一個標(biāo)準(zhǔn)滴定曲線：如果有一個pH計，重復(fù)上述滴定過程，同時用計，重復(fù)上述滴定過程，同時用pH計測定體計測定體系的系的pH值，到達(dá)滴定終點(diǎn)后，繼續(xù)滴加氫氧化鈉并記錄值，到達(dá)滴定終點(diǎn)后，繼續(xù)滴加氫氧化鈉并記錄pH值，作一張（滴定劑值，作一張（滴定劑消耗量消耗量vs pH值的）滴定曲線圖。值的）滴定曲線圖。3. Equivalents of Acid Using th

29、e 1 N solution of NaOH, determine the number of equivalents in two samples of benzoic acid. Carry out the procedure for the two determinations simultaneously. From this value calculate the equivalent weight of the acid. The solid should be weighed in a beaker and should be dissolved in about 25 ml o

30、f ethyl alcohol before titration with the base. Between 2.0 and 2.2 g of the solid provide the best results. Record all data and make all calculations necessary to determine the equivalent weight of the solid acid. Compare your experimental value with the equivalent weight of benzoic acid (calculated from the formula) and determine the percentage of error of your work. F 3. 酸的當(dāng)量：用一當(dāng)量濃度的氫氧化鈉，測定兩個苯甲酸樣品的當(dāng)量數(shù)，兩酸的當(dāng)量：用一當(dāng)量濃度的氫氧化鈉，測定兩個苯甲酸樣品的當(dāng)量數(shù)，兩個測定同時進(jìn)行，通過滴定體積計算出酸的當(dāng)量。先將固體酸稱到燒杯中，加入個測定同時進(jìn)行，通過滴定體積計算出酸的當(dāng)量。先將固體酸稱到燒杯中，加入25 mL乙醇溶解再用堿滴定，乙醇溶解再用堿滴定，2.02.2 g樣品可獲得最佳的結(jié)果。記錄所有