2013年最新分析化学实验 英文 - 分析化学课件武大第五版

2013年最新分析化学实验 英文 - 分析化学课件武大第五版 Experiment 1 PH standard solution preparation and concentration comparison A Purpose of the experiment 1. Learning to master the instrument commonly used in titration of washing and proper use. 2. Titration analysis of practice operations through an initial grasp of methyl orange, phenolphthalein indicator end point determination. 3. Grasp the pH standard solution preparation method. Two Experimental principle 0.1 mol / L HCl solution (strong acid) and 0.1 mol / L NaOH solution (alkaline) when each titration, pHsp 7.0, the pH titration jump range of 4.3 - 9.7, select the color range in jump indicator ( such as methyl orange, phenolphthalein), can be measured to ensure sufficient accuracy. In the case of the same indicator, a certain concentration of HCl solution and NaOH solution each titration, the ratio of the volume consumed by V / V should be certain, to, you can test titration technique and the ability HClNaOH to judge the end . Three Main reagents and instruments 1. HCl solution of 6 mol / L. 2. Saturated NaOH solution (concentration of about 15 - 19 mol / L). 3. Methyl orange solution 1g / L. 4. Phenolphthalein solution of 2 g / L ethanol. Four Experimental procedure 1. Solution preparation (1) 0.1 mol / L HCl solution in a clean graduated cylinder to measure small-about 8.3 mL 6 mol / L HCl solution was poured into 480 mL of water containing about 500 mL reagent bottle, add water, diluted to 500 mL, covered with glass Cyprus, shaking. (2) 0.1 mol / L NaOH solution in a clean graduated cylinder to measure small about 3.3 mL saturated NaOH, poured into 480 mL of water containing about 500 mL reagent bottle, add water, diluted to 500 mL, covered with rubber plug, shake uniform. 2. Titration between pH solution (1) with 0.1 mol / L NaOH alkaline solution rinse buret 2 - 3 times, each time with 5 - 10 mL solution rinse. And then directly into the alkaline titrant buret in the buret liquid level adjusted to 0.00 scale. (2) with 0.1 mol / L HCl solution, rinse Acid Burette 2 - 3 times, each time with 5 - 10 mL solution rinse. And then directly into the acidic titrant in the buret, buret liquid level adjusted to0.00 scale. (3) from the buret in the release of alkaline NaOH solution 20.00 mL in 250 mL conical flask, add drops of methyl orange indicator, with 0.1 mol / L HCl titration to change 2 from yellow to orange. Note reading, parallel to the determination of three. Data record in Table 1, calculate the volume ratio V / V NaOH.HCl (4) from the buret in the release of acidic solution of 20.00 mL HCl in 250 mL conical flask, add 2 drops of phenolphthalein indicator, with 0.1 mol / L NaOH solution titration to change from colorless to reddish, the red does not maintain the 30s fade to end. Note reading, parallel to the determination of three. Data recorded in Table 2, and Table 2, the volume calculate the volume ratio V / V and compare the Table 1NaOH,HCl ratio V / V NaOH.HCl Five Data Processing In this study, the data recording and processing are shown in Table 1 and Table 2.. Table 1 HCl NaOH solution titration (using methyl orange as indicator) Titration Number 1 2 3 Records Project V / mL 20.00 20.00 20.00 NaOH V / mL HCl V / V HClNaOH V / V average HClNaOH d i d r Table 2 NaOH titration of HCl solution (phenolphthalein as indicator) Titration Number 1 2 3 Records Project V / mL 20.00 20.00 20.00 HCl V / mL NaOH V / V HClNaOH V / V average HClNaOH d i d r Six Thinking problems 1. HCl and NaOH solution concentration can be accurately prepared me directly? Why? 2. Titration analysis in the experiment, buret, pipet titrator and why the need to take to move the solution washed several times Run? Titration flask used have to apply the titrant Run wash? Why? 3. Why NaOH titration with HCl using methyl orange as an indicator when, while titration of HCl with NaOH using phenolphthalein as an indicator of when (or other appropriate indicator)? Experiment 2 NaOH solution calibration and the determination of total acidity in vinegar A Purpose of the experiment 1. To understand base material and potassium dihydrogen phthalate (KHP) the nature of its application. 2. Master NaOH standard solution of the preparation, standardization and save points. 3. Titration weak acid strong base titration to master the process of jump range and choice of indicator principle. 4. To understand the analysis of total acidity of vinegar. Two Experimental principle - 5), Acetic acid is an organic weak acid (Ka = 1.8 × 10 and NaOH in the reaction is HAc + NaOH = NaAc + H O 2 Reaction product was weak alkali salt, alkaline titration jump in the context of such optional alkaline range of phenolphthalein indicator color. Consumption of acetic acid in vinegar is about 30 - 50 g / L (3 - 5%). NaOH standard solution prepared with the calibration method, commonly used potassium dihydrogen phthalate (KHP) as the base material and calibration of its concentration. Calibration reaction is: KHC H O + NaOH = NaKC H O + H O 8448442 Three Main reagents and instruments 1. Saturated NaOH solution (concentration of about 15 - 19 mol / L). 2. Phenolphthalein solution of 2 g / L ethanol. 3. Potassium dihydrogen phthalate (KHP) standard substance 1h at 100-125 ? after drying, placed in a desiccator spare. Four Experimental procedure 1. 0.1 mol / L NaOH standard solution in the preparation and calibration (1) 0.1 mol / L NaOH solution prepared in a clean small graduated cylinder to measure about 3.3 mL saturated NaOH, poured into 480 mL of water containing about 500 mL reagent bottle, add water, diluted to 500 mL, covered with rubber plug , shake well. (2) 0.1 mol / L NaOH solution to poor calibration of the weighing bottle, weighed KHP three subtraction, each 0.4 - 0.6 g, were poured into 250 mL conical flask, adding 25 - 35 mL of water, heating to KHP to dissolve completely. Coolish after blowing flask with distilled water (why?). When completely cooled solution by adding 2 - 3 drops of phenolphthalein indicator, calibrated with NaOH solution to be titrated to maintain the 30s reddish and shall end not fade. Note the reading, the data records shown in Table 1, calculate the concentration of NaOH solution. 2. Determination of total acidity in vinegar Pipet 25.00 mL of vinegar solution in 250 mL conical flask, add 2 drops of phenolphthalein indicator, titrated with NaOH standard solution changed from colorless to reddish, the red does not fade as the end to keep 30s. Note reading, parallel to the determination of three. Data recorded in Table 2, calculate the total acidity of vinegar, the result in g/100 mL said. Five Data Processing In this study, the data recording and processing are shown in Table 1 and Table 2.. Table 1 NaOH standard solution calibration Titration Number 1 2 3 Records Project m / g KHP V / mL NaOH C / mol / L NaOH C average NaOH d i d r Table 2 Determination of total acidity in vinegar Titration Number 1 2 3 Records Project V / mL 25.00 25.00 25.00 HAc V / mL NaOH C / g / 100mL HAc C average HAc d i d r Six Thinking problems 1. Calibration standard solution of NaOH the base material used is what? Compared with other benchmark materials, it has any significant advantage? 2. Determination of vinegar content, why use phenolphthalein as the indicator? Whether the use of methyl orange or methyl red as indicator? 3. Phenolphthalein indicator from colorless to reddish, the solution pH, how many? Red solution in the air, then placed into a colorless why? Experiment 3 HCl solution, calibration and determination of total alkalinity of alkali dust A Purpose of the experiment 1. Learn anhydrous sodium carbonate and borax base material and the nature of its application. 2. Master HCl standard solution of the preparation and calibration procedure. 3. To master the dual bases, titration acid titration process of jump range and choice of indicator principle. 4. To master the basic elements of quantitative transfer operation. Two Experimental principle Alkaline ash (that is, industrial soda ash) is mainly composed of sodium carbonate, soda brand name, which may also contain a small amount of NaCl, Na SO NaOH and NaHCO 4,2 and other ingredients. Often HCl standard solution for the determination of total 3 alkalinity titrant to measure the quality of the product. Titration reaction Na CO + 2HCl = 2NaCl + H CO 2323 H CO = H O + CO ? 2322 Reaction H CO is easy to form the supersaturated solution and decomposes to CO 23 and escape. Stoichiometric point, pH value of 3.8 - 3.9, can be used methyl orange 2 as indicator, titrated with HCl standard solution, the solution changed from yellow to orange to end. Sample of NaHCO were in the same time and. 3 As the sample is easy to absorb moisture and CO the sample should be dried at 270-300 ? 2, 2 h, to remove adsorbed water and to all of NaHCO into Na CO alkali dust of the 3,32 total alkalinity is usually Or Said that as the poor uniformity of samples, more samples should be weighed to make it more representative. Determination of allowable error may be relaxed. Calibration method using HCl standard solution preparation, often with methyl orange as indicator, with anhydrous Na CO as the base material and calibration concentration. 23 Calibration reaction is: Na CO + 2HCl = 2NaCl + H CO 2323 Can also be used borax (Na B O ? 10H O) as the base material, using methyl red as 2472 indicator, calibration standard solution of HCl concentration. Calibration reaction is: Na B O ? 10H O + 2HCl = 2NaCl + 4H BO + H O 2472332 Three Main reagents and instruments 1. HCl solution of 6 mol / L. 2. Anhydrous Na CO base material Drying at 180 ? for 2 - 3 h later, placed in 23 a desiccator spare. 3. Methyl orange solution 1g / L. Four Experimental procedure 1. 0.1 mol / L HCl standard solution for preparation and calibration (1) 0.1 mol / L HCl solution prepared in a clean graduated cylinder to measure small-about 8.3 mL 6 mol / L HCl solution was poured into 480 mL of water containing about 500 mL reagent bottle, add water, diluted to 500 mL, cover the glass stopper, shake. (2) 0.1 mol / L HCl solution to poor calibration of the weighing bottle, subtraction, said anhydrous Na CO three, each of 0.15 - 0.20 g, respectively, into 250 mL conical 23 flask, adding 25 - 35 mL water, heated to completely dissolve Na CO Coolish after 3.2 blowing flask with distilled water (why?). When completely cooled solution, add 2 drops of methyl orange indicator to be calibrated with HCl titration solution from yellow to orange as the end point exactly. Note the reading, the data records shown in Table 1, calculate the concentration of HCl solution. 2. Alkaline ash Determination of total alkalinity Accurately weighed sample 1.8 - 2 g and the beaker, add appropriate amount of water, heated to dissolve the sample completely. After cooling, quantitatively transfer the solution to 250 mL volumetric flask with water set to the mark, shake it well. Pipet 25.00 mL test solution three in 250 mL conical flask, adding 20 mL water and 2 drops of methyl orange indicator, titrated with HCl standard solution from yellow to orange as the end point exactly. Note the reading. Data recorded in Table 2, calculate the total alkalinity of the sample, the results indicated by Na O%. 2 Five Data Processing In this study, the data recording and processing are shown in Table 1 and Table 2.. Table 1 HCl standard solution for calibration Titration Number 1 2 3 Records Project m / G sodium V / mL HCl C / mol / L HCl C average HCl d i d r Table 2 Determination of total alkalinity of alkali dust (m = g) alkali gray Titration Number 1 2 3 Records Project V / ML 25.00 25.00 25.00 test V / mL HCl Na O% 2 Na O% average 2 d i d r Six Thinking problems 1. Why are prepared 0.1 mol / L HCl solution, 500 mL requirements take 6 mol / L HCl solution of 8.3 mL? Write a calculation formula. 2. Anhydrous Na CO kept properly, absorb the 1% water, with this reference material 23 and calibration of the concentration of HCl solution, what the impact on its results? 3. When titrated with HCl solution, the use of methyl orange and phenolphthalein indicator to distinguish the two samples are from the Na CO or Na CO 23-NaOH23-NaHCO 3 composition? 4. Demarcation of the two reference substances HCl, Na CO and anhydrous borax (Na 23 B O ? 10H O) is what advantages and disadvantages of each? 2472 Experiment 4 EDTA solution calibration and determination of water hardness A Purpose of the experiment 1. Complexometric titration study the theory and application. 2. Grasp the complexometric titration of the direct titration. 3. Master EDTA solution preparation and calibration. Two Experimental principle Determination of water hardness and total hardness of water into calcium - magnesium hardness of the former is to measure the total calcium and magnesium, the latter were measured concentration of calcium and magnesium. Countries in the world that the method of water hardness varies, generally use the degrees (?) said, 1 ? = 10 mg CaO / L. Less than 16 ? for the soft water, greater than 16 ? for the hard water. The total hardness of tap water generally is less than 16 ?. In addition, China also uses mmol / L or mg / L (CaCO as the unit of water 3) hardness. In this study EDTA complexometric titration of total water hardness. The ammonia in pH10 buffer to chrome black T as indicator, with triethanolamine, and Na S masking 23 +,3 +,2 +,2 +,2 +Fe Al Cu Pb Zn and other ions, with EDTA standard solution titration, can be directly measured total water hardness. Titration reaction 2 + +2 + ++ MgY Ca Mg Y ? CaY EDTA standard solution prepared with the calibration. In this experiment, chrome black T (EBT) as indicator, as the base material with CaCO concentration of 3 calibration. Chrome black T indicator to improve the color of sensitivity, can be added to an appropriate amount of MgY. Calibration reaction is: CaCO + 2HCl = 2CaCl + H CO 323 2 + + MgY ++ MgY Ca Y ? CaY Three Main reagents and instruments 1. EDTA solution 0.01 mol / L. 2. NH - NH Cl buffer solution of pH = 10. 34 CaCO 3 reference material dried at 110 ?, 2 h, coolish placed in the desiccator 3. after cooling to room temperature and set aside. 4. Eriochrome Black T indicator 5 g / L (containing 25% triethanolamine and 20% Na 2 S). 5. HCl solution 6mol / L. Four Experimental procedure 1. 0.01 mol / L EDTA standard solution for calibration Subtraction Method in the weighing bottle to accurately weigh 0.2 - 0.3 g CaCO poured 3, into 250 mL beaker, add a little water before wetting, cover the surface of dish, from beaker to beaker mouth Department dropping about 5 mL 6 mol / L HCl solution, so that CaCO is completely dissolved. Water 50 mL, micro boiling a few minutes to remove 3 CO After cooling, rinse the beaker and watch glass, quantitative transfer of CaCO 2. solution in 250 mL volumetric flask with water set to the mark, shake well. Pipet 32 +25.00 mL Ca solution in the 250 mL conical flask, adding 20 - 25 mL water and 5 - 10 mL MgY (obtained from the experiment in step 2), and then adding 10 mL NH - NH 3 Cl buffer solution , 3 drops of Eriochrome Black T indicator, immediately EDTA 4 titration, when the solution stabilized by a wine red to blue purple and then just end shall be. Note reading, measured three times in parallel, the data record shown in Table 1, calculate the concentration of EDTA solution. 2. Determination of water hardness Graduated cylinder to measure water with 100 mL in 250 mL conical flask, (adding 1 - 2 drops of acid to sample solution, boil a few minutes to remove CO Cooling), by 2. adding 10 mL NH - NH Cl buffer solution, 3 drops of Eriochrome Black T indicator, 34 immediately with EDTA titration, when the solution stabilized by a wine red to blue purple and then just shall end. Note reading, measured three times in parallel, the data record shown in Table 2, calculate the total water hardness, results in (?) said. Five Data Processing In this study, the data recording and processing are shown in Table 1 and Table 2. Table 1 EDTA standard solution for calibration Titration Number 1 2 3 Records Project G / G Calcium Carbonate V / mL Y C / mol / L Y C mean Y d i d r Table 2 Determination of water hardness Titration Number 1 2 3 Records Project V / ML 100 100 100 Water V / mL Y Total hardness (?) Average total hardness Six Thinking problems 1. EDTA used in this experiment with what indicator should be calibrated? The most appropriate benchmark for material that? 2. In the calibration process, adding MgY What is the role? MgY it should be accurate to join? 3. In this study, the total hardness in tap water (?) that should be reserved several significant figures? A brief explanation. Five calibration experiments EDTA solution and +,+32Bi Pb content of Determination A Purpose of the experiment 1. Control the acidity increase by the control theory and application of selective EDTA. 2. To master continuous titration with EDTA method. 3. Master EDTA solution preparation and calibration. Two Experimental principle Mixed ions were commonly used control acidity titration method, masking method can be demonstrated according to the side reaction coefficient of the possibility of their titration, respectively. +,+32 Bi Pb and EDTA can form a stable 1: 1 complex, lgK 27.94 and 18.04, respectively. Because of the difference lgK vary widely, it can make use of pH effect, control of +,3different acidity, for each titration. At pH ? 1 时titration Bi at pH ? 5 - 6 时 +.2titration of Pb EDTA standard solution prepared with the calibration. In this experiment, xylenol orange (XO) as indicator, calibrated with ZnO as the base material and its concentration. Calibration reaction is: ZnO + 2HCl = ZnCl + H O 22 2 + + Zn Y ? ZnY Three Main reagents and instruments 1. EDTA solution 0.01 mol / L. 2. Hexamethylenetetramine solution of 200 g / L. 3. ZnO base material and dried at 300 ? for 2 h, coolish placed in the desiccator after cooling to room temperature and set aside. 4. Xylenol orange (XO) indicator 2 g / L. 5. HCl solution of 6 mol / L. Four Experimental procedure 1. 0.01 mol / L EDTA standard solution for calibration Subtraction Method in the weighing bottle to accurately weigh 0.16 - 0.24 g ZnO, into 250 mL beaker, add a little water before wetting, cover the surface of dish, from beaker to beaker mouth Department dropping about 5 mL 6 mol / L HCl solution to ZnO completely dissolved. Water 20 mL, micro boiling a few minutes. After cooling, rinse the beaker 2 +and watch glass, quantitative transfer of Zn solution in 250 mL volumetric flask 2 +with water set to the mark, shake well. Pipet 25.00 mL solution of the Zn in 250 mL conical flask, dropping hexamethylenetetramine solution to a stable red solution was then over 3 mL, then add 2 drops of xylenol orange indicator immediately with EDTA titration, when the solution stabilized by the purple into a bright yellow orange and then just end shall be. Note reading, three parallel determination, calculated the concentration of EDTA solution. +,+2.3 Bi Pb 2 content of Determination +,+32 Accurately pipet Bi Pb test solution was 10.0 mL in 250 mL three conical flask, drops of xylenol orange indicator, titration with EDTA, (adding 1 - 2 drops to add 2 test solution acidification, boiling minutes to remove CO cooling), by adding 10 mL 2. NH - NH Cl buffer solution, when the solution from purple through orange and then 34+3just turned into a stable bright yellow shall be Bi in the end. Note reading, +3calculating mixture of Bi content results in g / L, said. +3 In the titration of Bi solution after the adding hexamethylenetetramine solution to a stable red solution was then over 3 mL, then add 2 drops of xylenol orange indicator, and immediately titrated with EDTA, when solution stabilized by the purple into a bright +2yellow orange and then just shall Pb in the end. Note reading, calculating mixture +2of Pb content, results in g / L, said. Five Data Processing In this study, data records and forms from the column. Six Thinking problems 1. EDTA used in this experiment with what indicator should be calibrated? The most appropriate benchmark for material that? 2. Why not NaOH, NaAc or ammonia, but with hexamethylenetetramine adjust pH to 5 - 6? experiment six Back titration samples of aluminum content in aluminum A Purpose of the experiment 1. Grasp the back titration. 2. Learn replacement titration. 3. Mental and physical, hands-on experimental design. Two Experimental principle 3 + Al is easy to form a series of polynuclear hydroxy complexes, the polynuclear hydroxyl 3 +complexes with EDTA complex and slow; the same time, Al closed indicator xylenol orange, it is usually determined by back titration of aluminum. Quantitative and adding 3 +excess EDTA standard solution, boil a few minutes at pH ? 3.5, so that Al and EDTA 2 +complex completely, then at pH 5 - 6, with xylenol orange as indicator, with Zn salt standard excess of EDTA solution and back titration of aluminum content. Reactive as follows: 3 + + Al Y = AlY (pH ? 3.5) 2 + + Zn Y = ZnY (pH5 - 6) (Indicator has just changed from yellow to purple XO) Three Main reagents and apparatus Aluminum nitrate samples; ZnO; HCl (1 +1), (1 +3); EDTA (0.01mol / L); xylenol orange (2 g / L); Hexamethylenetetramine (200 g / L); ammonia (1 +1). Four Experimental procedure 2 + 1 Zn salt standard solution preparation 0.20 - 0.21 g ZnO in a small beaker, dropping (1 +1) HCl to ZnO Weigh accurately completely dissolved, then supplement of 1 drop (1 +1) HCl, heating, cooling, into 250 mL volumetric flask , set the volume, shake and set aside. ZnO calculated according to the quality of the material in the amount of standard solution concentration (in Zn 2 + dollars). 2 0.01mol / L EDTA standard solution for preparation and calibration Measure out 50 mL EDTA solution (0.1mol / L) in the reagent bottle, diluted to 500 mL 2 +with distilled water around, shake and set aside. Dispense 25 mL Zn standard solution (three) in the conical flask, add 2 drops of xylenol orange, was added dropwise to the solution of hexamethylenetetramine just become purple, then over 3 mL; with homemade The EDTA titration to the solution just becomes bright yellow for the end, record the volume consumed EDTA solution. According to the data of the exact concentration of EDTA solution. 3 Determination of aluminum in aluminum-containing samples Weigh accurately 0.53 - 0.55 g aluminum nitrate samples in small beaker, add 3 drops (1 +3) HCl, add the appropriate amount of water dissolved, transferred to a 250 mL Dispense the Al test solution 25 mL (three) in volumetric flask, volume, shaking. the conical flask, were added 50 mL EDTA solution accuracy (about 0.01mol / L), 2 drops of xylenol orange, then yellow test solution, add ammonia to the solution was purple, together with (1 +3) HCl solution, the solution yellow. Boiled 3 min, cooling. Add 20 mL of hexamethylenetetramine, then the solution should be yellow, red if the solution must also dropping (1 +3) HCl, to turn yellow. Complement plus 1 drop of xylenol orange, 2 +Zn standard solution with flat to just drop into the purple to finish, recording the 2 +consumption of Zn standard solution volume. According to the experimental data of the content of aluminum in aluminum-containing samples (in percentage terms of quality). Five Data recording and processing Table 1 EDTA standard solution for calibration (m = g, c = mol / L) ZnOZnO Number 1 2 3 2 + V (mL) 25.00 25.00 25.00 Zn V (mL) EDTA c (mol / L) EDTA (Mol / L) d i d r Table 2 Determination of aluminum in aluminum-containing samples (G = g) sample Number 1 2 3 V (mL) 25.00 25.00 25.00 sample 2 + V (ML) Zn Al (%) (%) d i d r The formula is: Six Thinking problems 1. For complex alloy sample without replacement titration, while the use of back titration, the result is high or low? 2. Back titration with the replacement of EDTA used in titration What is the difference? Experiment 7 KMnO solution, H O 422 determination calibration and A Purpose of the experiment 1. Grasp the KMnO solution preparation and calibration process, understand the 4 autocatalytic reaction. 2. Master KMnO H O determination of the principles and methods. 422 3. On the KMnO have experience of the characteristics of its own indicator. 4 Two Experimental principle Hydrogen peroxide in the industry, biology, medicine, have a wide range of applications, therefore, often required to determine its practical content. Determination by KMnO H O content, often using KMnO in sulfuric acid solution standard solution direct 4224 titration. Titration reaction -+ 5H O +2 MnO 6 H + = Mn + + 5O ? + 8H O 2242222 The beginning of the slow reaction rate, reaction products to be generated after Mn +,2 2 + Mn as a catalyst to accelerate the reaction rate, it can be successfully titrated to a stable reddish presented to the end, so called auto-catalytic reaction. Slightly -6excessive titrant (2 × 10 mol / L) itself purple to display the end. KMnO standard solution prepared with the calibration method, often in dilute 4 sulfuric acid solution, at 75-85 ?, using Na C O as the base material, calibration 224 concentration. Calibration reaction is: --+ 5C O +2 MnO 16 H + = Mn + + 10CO ? + 8H O 24 242222 The calibration response is autocatalytic reaction, the chemical reaction process should pay attention to acidity, temperature and titration rate. Three Main reagents and instruments 1. H SO solution of 3 mol / L. 24 Na 2 C 2 O reference material Dried at 105 ? for 2 h after the backup. 2.4 3. KMnO solution of 0.02 mol / L. 4 Four Experimental procedure 1. KMnO solution preparation 4 Weigh KMnO solid 1.6 g, dissolved in 500 mL water, cover the surface of pan, heated 4 to boiling and maintain micro-boiling state 1 h, after cooling, with a porous glass funnel (No. 3 or 4) filter. Filtrate stored in a brown reagent bottle. The solution at room temperature, 2 - 3 days after the filtration reserve. 2. KMnO solution calibration 4 Subtraction Method in the weighing bottle to accurately weighed Na C O three, each 224of 0.15 - 0.20 g, respectively, into 250 mL conical flask, adding 50 - 60 mL water and 15 mL H SO , blowing a small amount of distilled water flask (Why?), heated to 75-85 ?, 24 hot to be calibrated with a solution ofWhen the reaction began KMnO titration. 4+,2 to slow titration, the solution had to be Mn the titration speed may be faster, until the solution showed reddish and continued for half a minute does not fade shall end. Data record in Table 1, calculate the concentration of KMnO solution. 4 3. H O content 22 Accurate, pipet 25.00 mL test solution in 250 mL conical flask, three, by adding 50 mL water and 20 mL H SO KMnO standard solution with a titration solution and 4,24 continued for half a minute showed reddish discoloration shall not end. When the +,2 reaction began to slow titration, the solution had to be Mn the titration speed may be accelerated. Data recorded in Table 2, calculation of test solution in H O content, 22results in g / L, said. Five Data Processing In this study, the data recording and processing are shown in Table 1 and Table 2.. Table 1 KMnO standard solution for calibration 4 Titration Number 1 2 3 Records Project M / G sodium oxalate V / mL KMnO4 C / mol / L KMnO4 C average KMnO4 d i d r Table H 2 O 2 content 2 Titration Number 1 2 3 Records Project V / ML 25.00 25.00 25.00 test V / mL KMnO4 C (g / L) H2O2 C average H2O2 d i d r Six Thinking problems 1. KMnO solution preparation process to use porous glass filter funnel, how can 4 quantitative filter paper filter? Why? 2. Prepared KMnO solution should pay attention to? With Na C O calibration 4224 solution, why start drops of KMnO purple disappear slowly? Then they KMnO 44 disappear faster and faster, until the endpoint of stability of the purple? 3. With KMnO H O determination, the ability to use HNO HCl or HAc control 4223,of acidity? Why? 4. Preparation of KMnO solution, the filtration after the filter on the adhesion 4 of the material for that? What material should be used to clean? 5. H O What are the important properties, should pay attention to what use? 22 Experiment 8 CuSO ? 5H O in the Cu content 42 A Purpose of the experiment 1. Master Na S O solution preparation and calibration points. 223 2. To understand the role of starch indicator principle. 3. Indirect iodometric method for the determination to master the principle and operation of copper. 4. To understand the decomposition of copper alloy samples. Two Experimental principle Copper alloy sample and CuSO ? 5H O in the determination of copper, generally use 42 the iodometric method. 2 + In weak acid solution, Cu and the role of excess KI to generate Cu I precipitation, while precipitation of I titration reaction 2, -+ ++++ Cu 2 4 I 6 H = 2 Cu I ? I 2 2 Precipitation of I with starch as indicator, with Na S O standard solution 2,223 titration: --- I + S O = I + S O 2223 22462 -2 +2 + I the reaction is reversible by adding excess KI, the reduction of Cu Cu and can become completely, but, CuI precipitate strongly adsorbed I then the results will 2, lower. The usual approach is to be incorporated in the near end of thiocyanate, the --12)15)into the solubility of smaller CuSCN (Ksp = 4.8 × 10 CuI (Ksp = 1.1 × 10 precipitation, the adsorption of iodine released CuI to respond more fully. That -- CuI + SCN = CuSCN + I - KSCN near the finish line should be added, or SCN would restore the abundance of I led to lower measured results. Solution pH should generally be controlled at 3.0 2, 2 +- 4.0 between. Acidity is too low, Cu easily hydrolyzed, the reaction is not complete, the result is low, and slow reaction rate, the end extension; acidity is too high, then -I oxidation by oxygen in the air as I so that the results high. 2, -,3 + Determination of copper in copper alloys, the samples of Fe oxidation of I affects the determination, but may be masked by adding NH HF NH HF is a good buffer 2.442 solution, can control the solution pH 3.0 - 4.0 between. Na S O standard solution prepared with the calibration method, often using K Cr 2232 O as the base material, calibration concentration. Calibration reaction is: 27 --+3 Cr O 6 I + 14 H + = Cr + + 3I + 7H O 27 2222 --- I + S O = I + S O 2223 22462 Three Main reagents and instruments 1. KI solution of 4%. Na 2 S 2 O solution of 0.02 mol / L. 2.3 3. K Cr O reference material In the 150 - 180 ?, after 2 h drying stand. 227 Starch solution, 5 g / L. 4. 5. KSCN solution of 5%. Four Experimental procedure 1. Na S O calibration solution 223 K Cr O solid 0.59 - 0.62 g, into the clean beaker, add Accurately weighed, 227 appropriate amount of water, so that K Cr O completely dissolved, quantitatively 227 transferred to 250 mL volumetric flask, diluted with water to the scale, Shake well. Accurate, pipet 25.00 mL K Cr O standard solution three in 250 mL conical flask, 227 adding 5 mL 6 mol / L HCl, 10 mL 4% KI solution, shake well and put the dark 5 min, when reaction completely, then add 100 mL of water to be calibrated with Na S O solution 223titrated to show yellow, then add 1 mL of starch solution and continue titration to show light green to end solution. Data record in Table 1, calculated Na S O 223concentration of the solution. CuSO ? 5H 2 O in the copper content 2.4 Weigh accurately CuSO ? 5H O solid 1.0 - 1.2 g, into the clean beaker, add a small 42 amount of water and HCl, so that CuSO ? 5H O is completely dissolved, the quantitative 42 transfer to 250 mL volumetric flask, diluted with water to scale, shake. Accurately the test solution, pipet 25.00 mL in 250 mL conical flask, three, by adding 10 mL 4% KI solution, with Na S O standard solution titration to show pale yellow solution. 223 Finally Then add 2 mL of starch solution, titration to show a light blue solution. add 10 KSCN solution, continue titration until the blue just disappears. Data recorded in Table 2, calculated CuSO ? 5H O in the copper content, the results 42 indicated by%. Five Data Processing In this study, the data recording and processing are shown in Table 1 and Table 2.. Table 1 Na S O standard solution for calibration 223 Titration Number 1 2 3 Records Project / G / ML / Mol / L Mean d i d r Table CuSO ? 5H 2 O in the copper content 24 Titration Number 1 2 3 Records Project V / ML 25.00 25.00 25.00 test / ML Cu% Cu% average d i d r Six Thinking problems 1. Iodometric determination of copper, why is often added NH HF Why near the finish 2?4to join KSCN? 2. Iodometric determination of copper, why should the weak acid medium work? The use of K Cr O calibration Na S O solution, the first to join 5 mL 6 mol / L HCl, and 227223 the use of Na S O titration by adding 100 mL of water when such dilution, and why? 223 3. Demarcation of Na S O solution of the base material have? To K Cr O 223227calibration Na S O solution, the end of the green is the color of what material? 223 Experiment 9 Mixed Alkali Analysis (double indicator method) A Purpose of the experiment 1. Grasp of the principles of mixed-alkali and results of calculation. 2. Design methods and reagents HCl standard solution calibration. Design of Mixed Alkali main steps. 3. 4. Examine the theoretical basis of chemistry and practical ability. Two Experimental principle Mixed base of mainly double-indicator method, barium chloride method And so on. Double indicator method is simple, applicability and so on. Double indicator method for the determination of the principles of mixed-base is: The sample was dissolved to phenolphthalein as indicator, titrated with HCl standard solution to the end, the consumption volume of HCl standard solution recorded as V then add methyl orange 1; as indicator and continue titration with HCl standard solution to the end, the consumption volume of HCl standard solution recorded as V If V V it indicates 2.2>1, that the composition of mixed alkali Na CO + NaHCO and according to the following 233, formula results: Type in c standard solution for the HCl concentration (mol / L); V V HCl standard HCl1,2 solution to the consumption volume (mL); , Were Na CO NaHCO the molecular weight; G for the sample weight (g). 23,3 (Phenolphthalein indicator into the red just colorless, methyl orange from yellow to orange just) Three Main reagents and apparatus Mixed alkali samples (to 25 g of anhydrous Na CO added to 10 g NaHCO used 3,23 mortars to 100 research projects, the mix); HCl (1:1), anhydrous Na CO (AR.) ; 23 phenolphthalein (0.1%); methyl orange (0.1%); Four Experimental procedure 1 0.1mol / L HCl standard solution for preparation and calibration Measure out 8.3 mL 1:1 HCl in the reagent bottle, adding 500 mL of water, shake well. Weigh 0.10 - 0.15 g of anhydrous Na CO three on the conical flask, adding about 25 23 mL of water, heated in the furnace on anhydrous Na CO to dissolve completely. After 23 cooling, add 2 drops of methyl orange, with 0.1 mol / L HCl standard solution titration to end solution just becomes orange, to label the volume of standard solution of HCl consumption, according to the consumption volume of HCl standard solution standard solution of HCl calculated the exact concentration, with a mol / L, said. 2 Analysis of Mixed Alkali Weigh 0.14 - 0.17 g samples of the three mixed alkali in conical flask, adding about 25 mL of water, heated in the furnace on the sample is completely dissolved. After cooling, add 2 drops of phenolphthalein with 0.1 mol / L HCl standard solution titration until the solution just becomes colorless as the end note of the consumption volume of HCl standard solution V the solution again by adding 2 drops of methyl orange, continue 1, titration with HCl standard solution to the solution just to orange for the end, note the standard solution of HCl consumed volume V under the V and V determine the 2;12 composition of mixed-alkali content of each component was calculated, the results indicated by% . Five Data recording and processing Calculated from the proposed form and results. Experiment 10 Iron Ore content (mercury-free be iron law) A Purpose of the experiment 1. Grasp the K Cr O standard solution for preparation and use. 227 Learning the hydrochloric acid solution of iron ore samples. 2. 3. Learning K Cr O Determination of the principles and operation of iron. 227 4. Understand that the iron law of mercury will enhance environmental awareness. 5. Diphenylamine sulfonate indicator of the action principle. Two Experimental principle Classic analysis of iron ore is K Cr O method, that is, ore with HCl after 2273 +2 +,decomposition to SnCl - HgCl to the joint reduction of Fe Fe then diphenylamine 22+.2 The sulfonate as indicator agent, with K Cr O standard solution titration Fe 227 method is higher accuracy, but the HgCl easily cause environmental pollution. 2 In recent years, many mercury-free be made of iron law, to overcome the environmental pollution HgCl In this study SnCl - combined reduction of methyl orange. The 2.23 +2 +2 +principle is: Sn to Fe and restore finished, excess Sn can be restored for the hydrogenation of methyl orange methyl orange and fading, not only indicates the reduction 2 +in the end, and Sn can continue to hydride reduction of methyl orange as N, N - 2 +dimethyl-p-phenylenediamine and the amino acid, excess Sn can eliminate. Above reaction is irreversible, so the reduction of methyl orange does not consume the product of K Cr O 7.22 2 + HCl concentration should be controlled in 4 mol / L, if more than 6 mol / L, Sn will 3 +be first reduced to colorless, methyl orange, not direct reaction of Fe reduction. HCl concentration less than 2 mol / L, the slow fading of methyl orange. Titration reaction -+33 Cr O 6 Fe + + 14 H + = Cr + + 6 Fe + + 7H O 27 2222 Titration jump range of 0.93 - 1.34 V, using the diphenylamine sulfonate as indicator, due to the conditions of her potential was 0.85 V, therefore, requires the added H 3-3 +3 +2 PO so that the resulting titration of Fe into Fe (HPO ) and reduce Fe / Fe 442+ electricity on the potential to jump into a range of 0.71 - 1.34 V, an indicator can -change color in this context, but also eliminates the FeCl Yellow on the end of 4 the interference observed. Sb (V), Sb (III) interfere with the experiment, should not exist. Three Main reagents and instruments 1. SnCl solution, 100 g / L, 50 g / L. 2 2. Methyl orange solution 2 g / L. In the 150 - 180 ?, after 2 h drying stand. 3. K Cr O reference material 227 H SO 4 - H PO 4 mixed acid to 15 mL concentrated H SO slowly increased 4.2324 to 70 mL water, cooled by adding 15 mL concentrated H PO and mix. 4,3 5. Diphenylamine sulfonate solution of 2 g / L. Four Experimental procedure 1. K Cr O standard solution preparation 227 Accurately weighed, K Cr O solid 0.59 - 0.62 g, into the clean beaker, add 227 appropriate amount of water, so that K Cr O completely dissolved, quantitatively 227 transferred to 250 mL volumetric flask, diluted with water to the scale, Shake well. Determination of iron ore 2. Iron ore powder accurately weighed 0.70 - 1.0 g, into the clean beaker, add a small amount of water, wetting, adding 20 mL concentrated HCl, the surface covered dish in the fume hood in the low-temperature thermal decomposition sample, if insoluble residue with color residue, can be dropping 20 - 30 drops of SnCl solution (100 g / L) 2 solubilization. Sample decomposed completely, the residue should be close to white, with a small amount of surface water, blowing dish and beaker wall, cooling, quantitatively transferred to 250 mL volumetric flask, diluted with water to the mark, shake well. Accurate, pipet 25.00 mL test solution in 250 mL conical flask, by adding 8 mL concentrated HCl, heated near boiling, hot solution was added dropwise SnCl solution 2 to become colorless, and then dropping to the solution of methyl orange light show pink. Immediately water cooled, add 50 mL distilled water, 20 mL parathion mixed acid, 4 drops of sodium diphenylamine immediately with K Cr O standard solution titrated 227 to a stable red to end. Three parallel determination, calculation of total iron content in iron ore, said the results to Fe%. Five Data Processing In this study, data records and forms from the column, and according to the data of total iron content in iron ore, said the results to Fe%. Six Thinking problems 1. K Cr O Why can accurately weigh the concentration of the solution prepared? 227 2. Decomposition of iron ore, why should at low temperature? If heated to boiling what impact will result? 3 + 3. SnCl reduction of Fe in the conditions? How to control the amount of SnCl 2,2 however? 2 + 4. To K Cr O titration of Fe solution, adding H PO What is the role? 22734 5. In this experiment, What is the role of methyl orange? Experiment 11 Determination of potassium permanganate, calcium limestone A Purpose 1. To learn the basic knowledge and precipitation separation operations (precipitation, filtration and washing, etc.). 2. Learn to use potassium permanganate method for the determination of calcium in limestone principles and methods. 3. Grasp of crystalline calcium oxalate precipitation and the separation conditions and washing CaC O precipitation method. 24 Two Experimental principle The main component of limestone is CaCO limestone with CaO good 45 - 53%, in addition 3, to containing SiO Fe O Al O and MgO and other impurities. 3,2,223 Determination of calcium in many ways, rapid titration method is complex, more accurate 2 +approach is to use the potassium permanganate method in this experiment, Ca ions will precipitate as CaC O the precipitate filtered and washed , soluble in dilute H 4,22 2 +SO solution, and then KMnO standard solution titration and Ca equivalent C 442-O ions, according to the amount of KMnO used in the calculation of the sample 4 24 content of calcium or calcium oxide, the main reaction as follows: -22 + + Ca 2C O = CaC O 2424 CaC O + H SO = Ca SO + H C O 24244224 -+ 5H C O MnO + 6H + = 2Mn + + 10CO + 8 H O 22424222 2 + This method is used with Mg ion and alkali metal samples, many other metal cations -should not exist, because of their C O are susceptible to the formation of 24 2 precipitation or coprecipitation positive error. CaC O is a weak acid salt precipitation, pH = 4 时, CaC O dissolution of the 2424 loss can be ignored. Commonly used in acidic solution by adding (NH C O and then 4,4) 22+dropping gradually and in solution of ammonia in the H ions to precipitate slowly CaC O formation, and finally control the solution pH value of 3.5 - 4.5 . This will 24 enable the CaC O precipitate completely, it will not form (CaOH) C O precipitate, 24224 and can be composed of certain particles thick, pure CaC O precipitation. 24 Other minerals of calcium, can also be applied to the determination. Three Main reagents and apparatus HCl (6mol / L); H SO (1 mol / L); methyl orange (0.1%); ammonia (3 mol / L); 24 ammonium citrate (10%); (NH C O solution (5%, 0.1%); AgNO (0.1 mol / L); 4) 2243 KMnO standard solution (0.02 mol / L); glass funnel, qualitative filter paper 4 (φ 9 or φ 11). Four Experimental procedure 1 KMnO standard solution for calibration: (program self) 4 2 determination of calcium in limestone Limestone sample accurately weighed 0.1 - 0.2 g in duplicate, placed in 250 mL beaker, [1],dropping a small amount of water wetting cover the surface of pan, slowly dropping 6mol / L HCl solution, 6 mL, while continuing to shake the beaker until the cessation of foam, carefully heated to boiling 2 min. The solution was diluted to 50 mL, add 2 drops of methyl orange, then add 15 mL 5% (NH C O solution. (If there is 4) 224 precipitation generated at this time should be dropping in stirring 6mol / L HCl solution to precipitate dissolved, do not pay more attention.) Heated to 70 - 80 ?, stirring constantly per second 1 - 2 drops the speed dropping 3 mol / L ammonia to the solution [2].[3].from red to orange Place the aging Filter paper with medium speed (or glass sand core funnel) to pour method filter. With [4],cold 0.1% (NH C O solution to washed sediment pour method 3 - 4 times and then 4) 224-cold water wash to wash solution without Cl ions up. With the precipitation will be posted on the original storage of filter paper inside of the beaker precipitation (precipitation to the cup). With 50 ml 1 mol / LH SO 24 solution, carefully wash the precipitate on the filter paper into the beaker, diluted with water to 100 mL, heated to 75 - 85 ?, with 0.02 mol / L KMnO standard solution 4[5],was titrated to the solution pink, filter paper and then immersed in the solution with the glass stirring rod, if the bleaching solution, and then dropping KMnO 4 solution until the pink is not stifled by the 30s and finish. According to KMnO 4 solution and the sample re-calculation of the amount of calcium in the sample (or CaO) percentage. Note [1] first used a small amount of water, wetting, so as not to add HCl, CO arising 2, out of the sample powder. [2] the solution pH value adjusted to 3.5 - 4.5, so that CaC O precipitate completely, 24 and MgC O did not precipitate. 24 [3] in order to precipitate heat aging. If precipitation has been completed, to be placed in the night, you do not need insulation. However, Mg content of the sample, should not keep well, so that after the deposition. [4] first use of dilute solution of washing precipitant, is using the same ion effect, decrease the solubility of precipitation, to reduce the loss of dissolved and washed away a lot of impurities. [5] in acidic solution, filter paper consumption of KMnO solution, the longer the 4 contact time, consume more, so only before the titration to the end to the filter paper immersed in solution. Thinking problems 1. Precipitate CaC O why should the acidic solution by adding precipitating agent 4,2 (NH C O then 70 - 80 ? when ammonia was added dropwise to the change of methyl 4,4) 22 orange orange Ershi CaC O precipitation? Why and when in the methyl orange indicator 24 for acidity? 2. Washing CaC O precipitation, why is first with dilute (NH C O solution as 244) 224-the washing liquid, and then washed with pure? How to determine C O ions have 24 2-been washed? How to determine Cl Ion has been washed? 3. If CaC O precipitate with filter paper with sulfuric acid treatment, and then 24 directly titrated with KMnO will have any effect? 4, CaC O 4 precipitate, the Why aging? 4.2 5. KMnO method and the complexometric titration of calcium What advantages and 4 disadvantages of each? Experiment 12 BaCl ? 2H O in the determination 22 of barium A Purpose 1. Learn determination BaCl ? 2H O in the barium content of the principles and 22 methods. 2. Preparation of master crystal precipitation, filtration, washing, burning, and constant weight of basic operating techniques. Two Experimental principle 2 +, BaSO gravimetric method, both for the determination of Ba can also be used to 4-2determine the SO content. 4 Weigh a certain amount of BaCl ? 2H O dissolved in water, add dilute HCl solution 22 acidification, heat until slightly boiling, constantly stirring, slowly add dilute, hot -+2H SO Ba and SO reaction, the formation of crystal precipitation. 4,224 Precipitated by aging, filtering, washing, charring, ash, after ignition to form BaSO weighing, you can find the BaCl ? 2H O in Ba content. 422 +,2 Determination of the weight with BaSO Ba generally in the 0.05 mol / L HCl medium 4 with precipitation, generally with dilute H SO as a precipitating agent, and 24 precipitating agent may be too much 50% - 100%. +,-,-,-2 2 Pb Sr + interfere with the determination. NO ClO Cl Other anions and 33+,+,+,2 3 +K Na Ca Fe cations can cause precipitation and other phenomena, it should be strictly controlled precipitation conditions, the phenomenon of reduced precipitation, in order to obtain pure BaSO crystal precipitation. 4 Three Main reagents and apparatus 1. H SO (1 mol / L, 0.01 mol / L). 24 2. HCl 2 mol / L. HNO 3 2 mol / L. 3. 4. AgNO 0.1 mol / L. 3 5. BaCl ? 2H O AR. 22 6. Porcelain crucible 25 mL, 2 - 3 个. 7. Quantitative filter paper (Φ 9 or φ 11), slow or medium speed. 8. Glass funnel 2. Four Experimental procedure 1. Preparation of sample and precipitation Weigh accurately BaCl ? 2H O sample 0.4 - 0.6 g in duplicate, were placed in 250 mL 22 beaker, add about 100 mL water, 3 mL 2 mol / L HCl solution, stirred solution, heated to near boiling. Another take mL 1 mol / LH SO 4 solution, two in two 100 mL beaker, add water, 30 42 mL, heated to near boiling, hot to the two H SO solution were dropwise manner with 24 a small dropper to Two hot solution of barium salt, and stir constantly with a glass rod until the two H SO solution added last. After sinking to be BaSO precipitation, 244 the supernatant liquid by adding 1 - 2 drops of 0.1 mol / LH SO solution, carefully 24 observe the precipitation is complete. After settling completely, cover the surface of pan, place the overnight aging. Can also be precipitated on a water bath or sand bath, the heat 40 min, and aging. 2. Precipitation filtration and washing With slow or medium speed filter paper to pour method filter. Dilute H SO solution 24 (about 0.01 mol / L) washed precipitate 3 - 4 times, each time about 10 mL. Then, quantitative precipitation transferred to filter paper, and with the precipitation broom clean from top to bottom inside of the beaker, and wipe with a small piece of filter dilute paper Beibi, this small piece of filter paper placed in the funnel, then wash -H SO 4 - 6 times until the washing liquid does not contain Cl Date. (In AgNO 24 solution test, how to test?) 3 3. Empty crucible of constant weight Two clean porcelain crucible on the (800 ? 20) ? muffle furnace ignition to constant weight. The first burning 40 min, the first time burning 40 min, the second subsequent burning 2 0 min. Burning gas lights can also be carried out. 4. Precipitation of burning and constant weight Folded filter paper bag will be placed in precipitation have been constant weight of the porcelain crucible, dried, carbonized, ash after (800 ? 20) ? muffle furnace ignition to constant weight. 6 Data processing In this study, data records and forms from the column, and according to the data of BaCl ? 2H O in Ba content. 22 Thinking problems 1. Why should dilute hot HCl solution dropwise under constant stirring and adding precipitant precipitate BaSO HCl by adding too much impact? 4? 2. Why in the hot solution precipitated BaSO but the cooling filter? Why crystal 4, precipitation aging? 3. What is the pour method filter? Washing sediment, why should a small amount of water with detergent solution or several times? 4. What is the ignition to constant weight? Experiment 13 Phenanthroline Spectrophotometric determination of iron (Condition test and determination of iron content in the sample) One purpose of the experiment 1. Learning bare absorption analysis method of experimental conditions. 2. Master Spectrophotometric determination of the principles and methods of iron. 3. Master UV2100 spectrophotometer is used. 2 Experimental Principle Spectrophotometric determination of iron is one of the methods used, the color reagent used are: phenanthroline, sulfosalicylic acid, thiocyanate, copper, iron reagent, 5-Br-PADAP so. Among them, phenanthroline spectrophotometry high sensitivity, good stability and easy to eliminate interference, which is widely used methods. 2 + At pH = 1.5 ~ 9.5 of the conditions, Fe ion and phenanthroline (Phen) generated very +:2 stable orange-red complex Fe (Phen) 3 4 Lg K of this complex = 21.3, molar absorption coefficient ε = 1.1 × 10 L / stability 3 +2 mol ? cm. Hair color before hydroxylamine hydrochloride to Fe ions reduced to Fe + ions, the reaction is as follows: 3 + + + ++++ 4 Fe NH 2 OH = 4 Fe 2 N 2 O H 2 O 4H 2 Determination, the control solution acidity at pH = 3-9 is more appropriate, high 3 +acidity, the reaction was slow; acidity is too low Fe ion hydrolysis, affecting color. +,+,+,+,3 2 2 2 + Bi Cd Hg Ag Zn and other ions with color reagent generated precipitation, +,+,2 2 2 +Ca Cu Ni and other ions form a color complex, so when these ions coexist should be aware of their interference. 3, apparatus and reagents 1. UV-2100 spectrophotometer, 50mL volumetric flask 8, pipette (1, 2, 5, 10mL) 2. Iron standard solution (100 μg / mL): Weigh accurately 0.8634 g NH Fe (SO ? 12H 44) 22 O (AR grade) in 200 mL beaker, add 20 mL 6mol / L HCl solution and the amount of water , dissolved, quantitatively transferred to a 1L volumetric flask, diluted with water to the mark, shake well. 3. Iron standard solution (10 μg / mL): accurate, pipet 10 mL iron standard solution (100 μg / mL) in 100mL volumetric flask, add 2 mL 6mol / L HCl solution, diluted with water to the mark, shake well. 4. Phenanthroline (1.5 g / L). 5. Hydroxylamine hydrochloride (100 g / L, now with the current distribution). 6. NaAc (1mol / L). 7. NaOH (1mol / L)). 8. HCl (6mol / L). 9. Iron sample test solution. 4, experimental procedures 1. Absorption curve and measuring the wavelength of choice With a pipette draw 0.0 mL and 1.0 mL iron standard solution (100 μg / mL) were injected into two 50mL volumetric flask, each adding 1 mL hydroxylamine hydrochloride solution, Then add 2 mL Phen, 5 mLNaAc, diluted with water to the mark, shake well. shake well. Place after 10 min, with a 1cm cuvette to reagent blank (ie 0.0 mL iron standard solution) as the reference solution, between the 470-560nm, measured once every 10 nm absorbance A, at the maximum absorption peak near measured once every 2 nm A. In the coordinates on paper, as the horizontal wavelength λ to the absorbance A for the vertical drawing A and λ curve, that is, absorption curve. Absorption curve obtained from the maximum absorption wavelength λ and determination of Fe as a suitable wavelength. max, Instrument specific operation is as follows: (1) spectrophotometer connected to the power, open the spectrophotometer power switch, cover the sample compartment lid, so that equipment self-test, if the spectrophotometer display "546, 100.0," shows that the self-test is completed. (2) reference solution and the analyte solution into cuvette, respectively, into the sample tank (As usual, the reference solution into the No. 1 slot), and make transparent cuvette face of quasi-optical path cover the sample compartment lid. (3) by the wavelength (wavelength) button, set the wavelength value (eg 470nm), the mode (Mode) is set to the absorbance A (Absorbance), according to OABS/100% T key, some time after the instrument will automatically display " 0.00 ", and then pull the sample rod to align optical solution under test, the data shown in the meter shall be tested solution at 470nm the absorbance A value of records A and the corresponding wavelength value of values. To promote the sample rod, re-aligned to optical reference solution. (4) by the wavelength (wavelength) button to reset the wavelength value (eg 480nm), the following above (3) step of the operation method. Repeat this operation until the value reaches 560nm wavelength set up (Note: Every change in one wavelength, should be back by OABS/100% T key, the instrument automatically displayed as "0.00"). 2. Working curve (standard curve) production Take iron standard solution were transferred (10 μg / mL) 0.0, 2.0, 4.0, 6.0, 8.0, 10.0 mL 50 mL volumetric flask in six (number corresponding to 0, 1, 2, 3, 4, 5), The added 1 mL hydroxylamine hydrochloride solution, shake, place 2 min. Then were added 2 mLPhen, 5 mL NaAc solution, shaking, diluted with water to the scale, shake, place 10 min. Cuvette with a 1cm to reagent blank (ie 0.0 mL iron standard solution) as the reference solution, measured at the selected wavelength, the measured absorbance of the solution A. Then the horizontal iron content, the absorbance A for the vertical calibration curves (standard curves). Instrument specific operation is as follows: (1) spectrophotometer connected to the power, open the spectrophotometer power switch, cover the sample compartment lid, so that equipment self-test, if the spectrophotometer display "546, 100.0," shows that the self-test is completed (if the instrument to complete the self-test , this step can be ignored.) (2) reference solution (ie, No. 0 solution) and 1, 2, 3 solution into cuvette, respectively, and then click into the sample tank (As usual, the reference solution into the No. 1 slot), and so that the transparent cuvette face quasi-optical path, covered with the sample compartment lid. (3) by the wavelength (wavelength) button, set the value of absorption wavelength of maximum absorption wavelength of the curve λ (eg 510nm), the mode (Mode) is set max to the absorbance A (Absorbance), according to OABS/100% T key After some time, equipment will automatically display "0.00", followed by pulling the sample tank lever, so that optical path followed by Alignment 1, 2, 3 solution, then the data shown in order of instrument 1, 2, 3 solution at λ the absorbance A value of A values were recorded. max (4) Open the sample compartment lid, remove the 1, 2, 3 solution, the 4, 5, solution into cuvette, respectively, followed by the Central Plains into the sample slots 1, 2, the location of the solution, cover the sample chamber lid , followed by pulling the sample tank lever, the meter shows the data were 4, 5, solution at λ value of the absorbance max A were recorded. 3. Unknown samples in the determination of iron content Sample test solution, pipet exactly 3.0 mL of iron three were three 50 mL volumetric flask, made by the Working curve method of solution preparation step, the various Then press the number measured reagents were added, the preparation of sample solution. steps to 0 as the reference solution, sample solutions were measured absorbance A. Note: The above 2., 3. 2 solution preparation and determination of absorbance should at the same time. 5, results processing 1. To the absorbance A for the vertical, horizontal wavelength absorption, rendering the relationship between A and λ curve, that is, absorption curve and the curve obtained from the absorption maximum absorption wavelength λ max. 2. To the absorbance A for the vertical, horizontal iron content, rendering the working curve (standard curve). The standard curve drawn by the re-found a moderate iron 2 +-Phenconcentration corresponding absorbance A, calculated Fe complex molar absorption coefficient ε. 3. Under the iron-third of the sample solution absorbance A, on average, from the calibration curve the concentration of iron in the sample solution and calculate the iron content of unknown samples, the results with μ g / mL, said. VI Notes 1. Using the spectrophotometer, the spectrophotometer shall be in strict accordance with the rules to prevent damage Spectrophotometer. 2. This study, the cuvette is fragile items, use should be strictly in accordance with operational procedures cuvette used. 3. Preparation of test solution and standard solution should pay attention to the order of addition of reagents. 7, thinking title 1. The experiment to measure a variety of reagents which gauges were used when more appropriate? Why? 2. In this study, can choose which of several solution as the reference solution? Why? 3. Production of standard curves, the order of adding reagents can be arbitrarily changed? Why? 2 +-Phen 4. How to calculate the Fe complex molar absorption coefficient ε? The results show the problem? 5. Search sulfosalicylic acid spectrophotometric determination of the principles and major steps of iron, and in light of experiments to compare the two characteristics of spectrophotometric determination of iron. Appendix Cuvette washing and the use of Cuvette also called colorimetric pool, colorimetric cup, Photometric Analysis of auxiliary equipment, mainly used to dress the reference solution or the solution under test. Formed by the material points can be divided into the glass cuvette cuvette cuvette two types of quartz, often with visible spectrophotometry Glass cuvette, UV spectrophotometry is often used quartz cuvette. Divided according to specifications, cuvette can be divided into 1cm, 2cm, 3cm, 5cm various specifications. Cuvette washing, you can not scrub with a brush, the situation should be different according to different washing methods. Common washing method: pan soaking in the hot color than the washing liquid, some time after the rinse. Using the cuvette, the application of the index finger and thumb hold the ground glass cuvette surface (rough surface), washed with distilled water cuvette Run - 3 times, 2 then when liquid rinse cuvette 2 - 3 times then load to be liquid, the volume of solution into cuvette total volume of 2 / 3 - 3 / 4 respectively. Finally, the lens than the color of paper or filter paper dry pan, into the sample slot, and to align optical transparent cuvette surface. After testing should cuvette solution drained, wash with detergent solution or distilled water, dried, loaded cuvette box, and note cuvette photometer box number and the corresponding number. Cuvette is fragile items, and use in the washing process, should be careful not to clash with other hard objects, with lens paper or filter paper wipe cuvette, the action should be gentle. Experiment 15 PAR Determination of Trace Vanadium One purpose of the experiment 1. UV-2100 spectrophotometer to understand the basic structure and use. 2. Preliminary Determination of Trace Vanadium grasp the basis of experimental techniques. 3. Spectrophotometric analysis and understanding of the relationship between the conditions and basis of measurement. Second, the basic principle V (?) is an important element of the human body, from the Pharmaceutical Research [1]:shows that V (?) compounds have similar in vivo properties of insulin in adipose tissue and skeletal muscle glycogen to stimulate glucose uptake ) synthesis and glycolysis ) glucose oxidase to reduce food absorption, is a promising drug for treating diabetes. Vanadium is an important alloying element in steel alloys, vanadium steel has some special mechanical properties, such as improving the tensile strength of steel and the yield point, in particular can improve the steel's high temperature [2].strength Therefore, V (?) The determination of the actual work of great significance. The analysis methods include titrimetry, spectrophotometry and atomic V (?) spectrometry. Spectrophotometric Determination of Trace Vanadium is one of the main methods, the color reagent are: tantalum reagent (N-benzoyl-N-phenyl hydroxylamine), 4 - (2 - pyridylazo) resorcinol (PAR) and so on. Which, PAR is the Determination of Trace Vanadium common reagents. Figure 1-13 4 - (2 - pyridylazo) resorcinol (PAR) 4 - (2 - pyridylazo) resorcinol (PAR) in the context of pH1 ~ 7 and V (?) ions react In pH1 ~ 4.5, the formation to produce several orange-red water-soluble 1: 1 complex. 4of λ = 525nm, ε was 1.6 × 10 complexes; at pH4.5 ~ 7, the formation of λ = 545nm, maxmax4ε was 3.6 × 10 complexes. Vanadium complexes in the wavelength λ the excess max, reagent had no significant interference. Common cations interfere with the color system available DCTA (1, 2 - diaminocyclohexane tetraacetic acid) masking; iron and titanium fluoride can interfere with masking. EDTA to destroy V-PAR complexes, tartrate, oxalate, phosphate and fluoride has little effect. 3. Instruments and reagents 1. UV-2100 spectrophotometer, 25mL colorimetric tube (or flask), 1mL, 2mL, 5mL pipette and so on. 2. PAR: 0.02% ethanol - water (1: 1) solution. 3. Vanadium standard solution (0.5mg/mL): dissolve 1.149g NH VO in 10mL of 43 ammonia (1: 1), acidified with 10mLHNO constant volume with distilled water 3, to 1L. 4. Vanadium standard solution (10.0 μg / mL): Dispense 2.0 mL of vanadium standard solution (0.5mg/mL) in 100 mL volumetric flask with water set to the mark, shake well and set aside. 5. HAc-NaAc buffer solution (pH = 5.0): the 50g Na Ac ? 3H O dissolved in 2 adequate water, plus 6 mol / LH Ac 34mL, set the volume to 500mL. 4. Experimental procedure Absorption curve is 1. In 50 mL volumetric flask, then added to the 10.0μg/mL V (?) standard solution 3.0mL, 8.0mL HAc-NaAc (pH = 5.0) buffer solution, then add 0.02% PAR solution, 4.0mL, set to the mark and shake uniform. After 10 minutes, with reagent blank as reference, with the 1cm cuvette, scanning from 470 ~ 600nm (470-500nm every 10nm, 500-540nm every 5nm, 540-550nm 5nm, 570-600nm every 10nm scan once), at intervals of 1nm, 550-570nm every records corresponding to the absorbance A. With λ as the abscissa, A vertical axis, draw the absorption curve, obtained under the absorption curve with the maximum absorption wavelength λ (see test 17 equipment operators). max 2. PAR amount of In 50 mL volumetric flask, then added to the 10.0μg/mL V (?) standard solution 2.0 mL, 8.0 mL HAc-NaAc (pH = 5.0) buffer solution, then adding 0.02% PAR solution were 1.0, 2.0, 4.0, 5.0, 6.0, 8.0 mL, set to the mark and shake. 5 minutes to reagent blank as reference, with the 1cm cuvette, in the chosen λ absorbance was determined at A, max the experimental results to determine the optimal dosage of PAR (see test 17 equipment operators). 3. Settling time In 50 mL volumetric flask, then added to the 10.0μg/mL V (?) standard solution 2.0 mL, 8.0 mL HAc-NaAc (pH = 5.0) buffer solution, then add 0.02% PAR solution, 4.0 mL, set to the mark and shake uniform. 5 minutes to reagent blank as reference, with the 1cm cuvette, in the chosen λ absorbance was determined at A. Tested once every 30 max minutes after the absorbance A, according to A change in the color system to determine the stability of the time (see experiments 17 instrument operation). 4. The work of the production curve In 50 mL volumetric flask, then added to the 10.0μg/mL V (?) standard solution 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 mL and 8.0 mL HAc-NaAc (pH = 5.0) buffer solution, then add 0.02% PAR solution, 4.0 mL, set to the mark and shake. 5 minutes to reagent blank as reference, with the 1cm cuvette, in the chosen λ absorbance was determined at A. Curve and max the experimental data and determine the linear range (see experiment 17 instrument operation). 5. Unknown fluid analysis Dispense unknown liquid 4.0mL in 50 mL volumetric flask three, by adding 8.0mL HAc-NaAc (pH = 5.0) buffer solution, then add 0.02% PAR solution, 4.0 mL, set to the mark and shake. 5 minutes to reagent blank as reference, with the 1cm cuvette, in the chosen λ absorbance was determined at A, under the working curve to determine max the unknown solution V (?) content (results in μ g / mL indicated) (see experiment 17 instrument operation). 5, results processing 1. Drawing V (?)-PAR complex absorption curve, and pointed out that the maximum absorption wavelength, 2. Draw PAR consumption curve, and that the appropriate amount of PAR, 3. Curve and calculation of V (?)-PAR complex molar absorption coefficient ε, and calculate the unknown solution V (V) content (results in μ g / mL indicated), 4. That the stability of the color system of the time. Six Thinking problems 1. How to improve the selectivity of the method? 2. Why choose this experiment under the conditions of pH4.5 ~ 7 color? 3. How to determine the stability of the color system of the time? 4. How to evaluate the sensitivity of spectrophotometry? In this study, the sensitivity of the color system used to?