MINISTRY OF SCIENCE AND EDUCATION OF THE REPUBLIC OF KAZAKHSTAN

STATE UNIVERSITY OF SEMEY named after SHAKARIM

Methodical recommendations for conducting laboratory works

«PHYSICAL METHODS OF CHEMICAL RESEARCH»

for the specialty5B011200– «Chemistry»

Semey -2015

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LABORATORY WORKS

Methodical recommendations for conducting laboratory worksLaboratory studies promotes knowledge of the physical methods of chemical

research, the student develops independence and instills the skills of the experiment. In order to work in the laboratory took place successfully, you must first explore the theoretical material from textbooks, lecture notes and the benefits of chemical workshops. This produces a conscious attitude to the implementation of experimental techniques, the work itself will be understood, and, therefore, and understood. Working in the chemistry lab should strictly observe the safety rules and regulations of the chemical utensils and appliances. We must learn to use chemical agents, chemical equipment, which are listed in the guidelines for the work on the chemical workshop. Guidelines should not be a straitjacket, and to deprive independence, but rather follow the orders of speeds up, prevents possible damage to equipment, glassware and reagents. The success of the experimental work depends not only on the correctness of the choice of working methods, the sequence of measurement, weight measurements, but also on the correct systematic recording of results. By the implementation of the laboratory work allowed students with admission after verification of a teacher of theoretical knowledge on the subject, knowledge of laboratory methods of work and prepared to conduct lab journal entries on the topic. After completing the laboratory work the student must bring order to your workplace and deliver them on duty or technician. After processing the results in the lab book the student must submit the report teacher.

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Laboratory work №1

Subject: Determination of iron in the form of thiocyanate complexReagents: Standard iron(III) salt solution-from the titer of 0.1 mg/ml iron,0.8635 g ferric alum FeNH4(SO4)*12 H2O dissolved in water to which is added 5 ml of concentrated H2SO4 and the solution is diluted with water in a volumetric flask to 1 liter; potassium thiocyanate and ammonium -10% solution; HNO3(1:1) is made from concentrated HNO3

Method of determination

Construction of the calibration curve.Progress:In the five flasks 50 ml sequentially inject 0,5;1,0;1,5;2,0;2,5ml of the standard solution of iron salts. All samples were acidified with 1 ml of nitric acid (1:1), it adds 5ml of 10% ammonium thiocyanate or potassium, bring to the mark with water, stir and photo metrically using photoelectocolormeter differet brands. Measurements of conduct with a correspondingly pre-selected color filter and a cuvette. As a reference solution to take distilled water.The measurement results are written in the table 2.3 and the data obtained in the plot the coordinates of the optical density, the iron content.

Analysis of the test solution.To test solution prepared in 50 ml volumetric flask, add the same quantity of reagents, carry out the same operations as in the construction of the calibration curve. The iron content is found from the calibration curve.

№ standard solution

The content of Fe in 50ml Q=T*V,mg

Optical density,A

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Laboratory work №2,3

Subject: Determination of copper (II) in the form ammine.Reagents:NH4OH(concentrated), copper standard solution with a titre of 2 mg / ml copper( sample of 7.854 g of recrystallized copper sulfate CuSO4*5H2O dissolved in distilled water, add 10 mL H2SO4 (p=1.84) and the solution was adjusted to 1 liter volume with water. Method of determination. Construction of the calibration curve.Progress:Take five flasks 50 ml, placed in flasks standard copper solution in ml: 1.0, 2,5;4,0;5,5;7,0 respectively. To each flask was added 5 ml of ammonia (concentrated solution), bring to the mark with distilled water, mix and photometrically using photoelectrocolorimeter different brands. Measurement of conduct at a pre-selected color filter and cuvette. The solution serves as a comparison with distilled water. The measurement results are written in the table 2.4 and the data obtained in the plot the coordinates of the optical density, the copper content. Analysis of the test solution.To test solution prepared in 50 ml volumetric flask, add the same quantity of reagents, carry out the same operations as in the construction of the calibration curve. The copper content is found from the calibration curve.#standard solution

The content of Cu in 50ml Q=T*V,mg

Optical density,A

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Laboratory work № 4

Subject: Determination of sucrose concentration in solution by refractometry method.Objective: to establish the concentration of sucrose solution refractive index.Reagents: the refractometer type RP and RPU; aqueous solutions of sugars.Progress:Prepare a solution of sucrose in water the following concentrations (%): 20, 40, 60, 80. Measure the refractive index of these solutions refractometer. Receiving values of refractive indices for each of the prescribed compositions construct a calibration curve(on graph paper), postponing the refractive index on the ordinate and the concentration of the solution- the abscissa. Determine the refractive index of the control solution of unknown concentration by refractometer. According to the refractive index, using the calibration curve are sugar content of the solution.The experimental results are tabulated in the form:The concentration

of the solutionsN solutions N reference

solutionThe sugar

concentration in the test solution

Report for work:1. Construct a graph of the refractive index of the concentration of the aqueous solution

of sugar.2. On the refractive index, using a calibration curve to find the concentration of sucrose

solution3. Fill in the table.

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Laboratory work № 5

Subject: Polarimetric determination of the content of the optically active substance (glucose) in solution from the calibration curve.Objective: Determine the content of optically active substance (glucose) in solution from the calibration curve by polarimetric analysis.Reagents: An optically active substance is supposed to determine the contents of which in this solution; suitable solvents polarimeter.Progress:Small chemical cups are weighed on an analytical balance 2,4,6,8,10 g glucose. Add a little water and the resulting syrup quantitatively transferred to a volumetric flasks 50 ml. Added to the mark with distilled water and mix thoroughly, repeatedly turning securely stoppered flask. Washed thoroughly rinsed tubular cuvette polarimeter small amount of volumetric flasks glucose solution, and then filled with the same solution. The tube is placed in the polarimeter and determine the angle of rotation of polarization plane of light passing through the solution. From the measured angles of rotation of the polarization plane of the standard solutions build a calibration curve. Then measure the angle of rotation for the unknown concentration of the test solution and its magnitude is determined schedule.

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Laboratory work №6

Subject: Potentiometric determination of pH of the water.Reagents: pH meter - millivoltmeter; pH 121 (or other mark); glass electrode with hydrogen function ESL-43-07, ESL-63-07; silver chloride reference electrode types EVL-1M3; glass capacity of 50 or 100 ml; standard buffer solutions with different pH.Progress:Before working a glass electrode in water or kept in a weak acid solution. The setting device according to buffer solutions is carried out in the following order: glass poured into a buffer solution (e.g. pH = 4.01), it is lowered into the electrodes connected to the device electrodes. Turn on the device to the appropriate measurement range and the warm up for 10-15 minutes. Temperature corrector setting pointer to the appropriate temperature, the device is adapted to the pH buffer (a pH handle resistor 121- "Calibration"), check the device configuration other buffer solutions. In the event of readings from the pH of the solution by more than 0.5 pH (to the range 1-14) and 0.05 (range 1-4,4-9,9-14) necessary to carry out adjustment resistor handle "steepness" . Before each dipping the electrodes in electrode buffer solution is thoroughly washed with distilled water, excess water removed with filter paper. Readout on the instrument scale of pH was taken at 0.5-1 minute after the start of measurement.In a glass pour the water sample, which is required to determine the pH. The electrodes were washed with distilled water, excess water removed with filter paper. Immerse the electrodes in the test solution and measure pH.Calculate the concentration of hydrogen ions and hydroxide (in mol / l) [H+]=10-pH, [OH-]=10-pH-pK.

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Laboratory work №7

Subject: Potentiometric titration of the hydrochloric acid.Reagents: pH meter - millivoltmeter; pH 121; glass indicator electrode with hydrogen function ECL or ECL-43-07 63-07; silver chloride reference electrode types EVL-1M3; magnetic stirrer; titration vessel with a capacity of 100 ml; burette 25 ml or 50; 10 ml pipette; volumetric flask 100 ml; HCl-0,1 standard solution mol / l (made from standard-titer); HCL solution was analyzed, after dilution with distilled water in a volumetric flask with 100 ml of a solution with a concentration of about 0.1 mol / l; NaOH solution of 0.1 mol / l; standard buffer solutions to adjust the pH meter.Progress:1. Preparation for the glass electrode and the device setting for the buffer solutions.2. Installation exact working concentration of sodium hydroxide solution. In a glass pipette for titration administered 10 ml of standard solution HCl added as distilled water to completely cover the working electrode surface. Turn the magnetic stirrer and the speed controller provide stirring solution. The burette is filled with titrant. Titration is carried out in a narrow pH range first scale "1-4", then titration as "4-9", etc. Thus, after each addition of titrant measured portions of the solution pH. Titrant added 0.5 ml of the initial section of the curve and titration 0.1-0.2 ml jump in the titration curve. The measurement results are entered into the table. Spend at least three titrations. The data obtained titration curves build pH-f (V, ml), which set the end point titration. Take the average value of equivalent volume of titrant VNaOH and concentration of C NaOH is calculated by the formula:CNaOH=(CHCl*VHCl)/VNaOH

Where V HCl - HCl volume of standard solution taken for titration, ml;C HCl- is the concentration of the standard solution of the HCl, mol / L;VNaOH -is the average volume of NaOH solution consumed for titration, ml.The end point of the titration are as the inflection point of the titration curve with one of the two methods described below.In the first method (Fig. 1.3.a.) is performed two parallel tangents (1) and (2). Then, through a portion of the titration curve vertical spend tangent (3) and divide it in half cut. The resulting spot "TE", corresponds to approximately the inflection point of the titration curve, and, accordingly, the end point of the titration.In the second method build differential titration curve, i.e. dependence ∆pH/∆V=f(V) .For this purpose, the titration data is converted, determining ∆pH and ∆pH/∆V for selected values V and find the "TE" as the point of its maximum (Fig. 1.3.b.)3. HCL solution to be analyzed in a volumetric flask with 100 ml dilute to the mark with distilled water and mix thoroughly. Transfer 10 ml of the solution in the titration beaker. Distilled water was added to completely cover the electrodes and the titration is carried out at least three times. According to the results of each build titration

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curves of potentiometric titration. Endpoint titration are one of the ways described above. Calculate the mean value of the titrant volume.HCL content was calculated according to the formula in the test solution:mHCl=( CNaOH* VNaOH*VK*MHCl)/ VHCl*100Where CNaOH- the concentration of sodium hydroxide solution in mol / l;VNaOH- average volume of sodium hydroxide solution consumed for titration in ml;VHCl- the volume of HCL solution. taken for titration, ml;VK- wherein the volume of the solution under investigation weighed acids ml (in this example, capacity measuring flask VK= 100 ml)MHCl-molar mass HCL (36.5 g/mol).

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Laboratory work №8

Subject: Determination of acetic acid by potentiometric titration.Reagents: pH meter - millivoltmeter; pH 121 (or other mark); glass electrode with hydrogen function ESL-43-07, ESL-63-07; silver chloride reference electrode types EVL-1M3; glass capacity of 50 or 100 ml; standard buffer solutions with different pH.Progress:1. Preparation for the glass electrode for the device buffer (see Ref. 1.1.2.). 2. Installation exact concentration of the working solution of sodium hydroxide (see Ref. 1.1.3). 3. In a 100 ml capacity flask pipette analyte vinegar 10 ml, diluted with distilled water to the mark and thoroughly mixed with 10 ml pipette solution was transferred to a titration beaker, titration is carried out as described in 1.1.3.The acetic acid m (CH3COOH) in g / 100 ml of acetic acid was calculated by the formula:mCH3COOH= (CNaOH*VNaOH*VK*MCH3COOH*100)/V1*1000*V2=(CNaOH*VNaOH*VK*6)/ V1* V2

WhereCNaOH- the concentration of sodium hydroxide solution in mol / l;VNaOH- is the average volume of NaOH solution consumed for titration, ml.VK- capacity volumetric flask, which dissolved taken to analyze the amount of vinegar V2 ml (in this example, volumetric flask VK=100ml);MCH3COOH- molar massCH3COOH (60 g/mol);V1-volume of diluted vinegar solution taken for titration, ml;V2 - volume of test solution of vinegar, taken for analysis, ml;

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Laboratory work №9

Subject: Amperometric determination of copper.Reagents: Solution Na2S2O3-0,05 M; potassium iodide, dry; sulfuric acid, 1M; test solution, H2SO4=10-3M solution; amperometric installation (see para. 1.2.1).Objective: amperometric determination of the concentration of copper.Progress:1. Prepare the installation and check the connections of its individual parts. Work carried out on a conventional amperometric installation diagram is shown in Fig. 1.8. With the rheostat is set equal to the potential of 0.53 V. When this potential iodine will be restored on a platinum electrode. 2. The titration cup placed 10 ml of the solution of copper (II), 25 ml of sulfuric acid solution (background), it is immersed in the electrodes and closes the circuit. This is a reduction of copper cathode (arrow galvanometer deflected). 3. Add 0.3-0.5 g of potassium iodide salts include mixer. On the galvanometer, a sharp drop to zero initial electricity- diffusion current copper. Such a sharp drop in current is explained practically complete binding of copper ions (II) of copper iodide. After this, the release of free iodine, while the current strength increases in proportion to the concentration of free iodine in solution. To complete the reaction, waiting for 2-5 minutes, until the maximum sustainable value to the galvanometer current.4. The contents of the cup is titrated with sodium thiosulfate by adding it to 1 ml and the fixing current, as titration which is reduced by the reaction 1.53 (after titration reach steady current value).The measurement results are entered into the table:V,ml 1 2 3 …..J,µA5. According to the results tabulated data plotted in the coordinates of the "power-current titrant volume" and find the equivalent point of the titration at the intersection of the horizontal line to the bottom line.6. Amperometric titrant consumption curve are calculated and copper mass in milligrams according to the formula:mCu= V*N*mэ

wheremCu- weight substances, mg;V -titrant consumption in Na2S2O3, ml;N-sodium thiosulphate concentration, mol / L;mэ -equivalent weight of the substance, g / mol.Titration was repeated twice.After graduating from the titration, amperometric setting show: disconnect the power source, electrodes and burette washed with distilled water.

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Laboratory work № 10

Subject: Conductometric determination of a monobasic acid.Progress:Preparat- aqueous acid solution. It is placed in a volumetric flask of 50 ml, brought up to the mark and thoroughly mixed. Pipette 10 ml aliquot of the solution in chemical flasks 100 ml (at bottom of the glass must be stirrer polyethylene sheath). Put the beaker on a magnetic stirrer, immersed electrodes so that they were in the center of glass and the lower edge of the protective glass has not reached the agitator is 5 mm. Stirrer, and topped up with distilled water until no circular openings in the cover glass electrode will be closed. Stirring is carried out for 1-2 min., After which the cell resistance was measured in accordance with the device instructions. After each addition of a certain amount of alkali resistance is measured. solution resistance increases to achieve the equivalence point with a further addition of alkali- decreases. After the equivalence point should be at least 4-5 points on the titration curve. If the curve is not a two intersecting straight lines, then near the equivalence point titration is necessary when re-add 0.1 ml of alkali. The experimental data are recorded in the table:

Titrant NaOH, ml 1 2 3 …..Resistance,r,Om

According to experimental data plotted by plotting the numerical values on the axes on the same scale. The weight of the free acid in the formulation in grams is calculated by the formula:m=(N NaOH*V equivalent*E Acid*Vflasks)/1000*V Pipette

whereE Acid-the equivalent weight of acid, g/mol;V Equivalent -volume at the equivalence point of the titrant, ml.

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Laboratory work №11

Subject: Adsorption Chromatography of inorganic ions.The essence of the method.In adsorption chromatography separation of the mixture components due to their different sorbed on the solid sorbent - alumina. Thus it can be separated both organic and inorganic substances.Preparation of the column for analysis.In the lower part of the glass tube height of 5-6 cm and a diameter of 6-7 mm is placed a cotton swab. Then the tube is made in small portions Al2O3 sorbent. To seal the sorbent tube tapped gently on a solid surface. Before you begin, you need to moisten the surface of the sorbent 2 drops of water.Method of determination.Prepare a chromatographic column. The three columns are administered 1-2 drops of pure Fe3+ and Cu2+ salts and Co2+, 2-4 drops accordingly. Column was then washed with 1-2 drops of distilled water. Chromatogram obtained of the individual compounds:iron(III) - brown;copper - blue;cobalt - pink.Then, a mixture of salts, which contribute to a tube 2 drops of solutions of Fe3+ salts, Co2+ and Cu2+ , mixed well. The resulting solution was injected into the fourth column, and washed with distilled water 1-2 drops. Chromatogram obtained salt mixture consisting of three zones, the location of which is due to the ability of various test substances adsorbed on alumina:Zone 1 - brown; 2 blue; 3 pink.

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Laboratory work №12Subject: Inorganic qualitative determination of ions by ion-exchange chromatography of milk and meat broth.Progress:Preparation of the solution for analysis.Test solution of 2-3 components of various salts mixed in equal volumes of 1 ml in a separate vessel.The obtained mixture solution in an amount of 1-5 drops pipetted applied to a column of alumina(III). Formed chromatography, in which the ions are arranged from top to bottom according to their imbibitions. The chromatogram was washed with water and then a chromatography column is made drop wise developer. Solutions developers in water is introduced into the column after each sorbent completely absorbed, or is formed of clear chromatograms.Detection of bismuth (III)and mercury(I) ions.The column make two drops of a mixture of mercury and bismuth salts, followed by one drop of water and 3 drops of 10% thiourea solution (developer).Sorption: Bi3+> [Hg]2+.Detection of the ions of chromium(III) and cobalt(II).The column of sorbent introduced three drops of a saturated solution of sodium hydrogen phosphate, 5 drops of solution the mixture of chromium and cobalt. Formed chromatogram at the top of the gray-blue color of chromium phosphate, less pink-purple zone cobalt phosphate.Sorption: Cr3+>Co2+.Detection of cobalt (II)and nickel(II) ions.The column of sorbent introduced two drops of the mixture of cobalt and nickel solution, washed with water, exhibit a 1% alcoholic acid solution rubeanic. Formed violet-red zone. Separation does not occur.Sorption: Co2+=Ni2+.The column of sorbent introduced two drops of the mixture of cobalt and nickel solution, washed with water, concentrated ammonia solution show, the top zone appears pink, brown color gradually acquiring characteristic ammine cobalt blue below- nickel ammine zone.Detection of lead (II)and silver(I) ions.The drop of the column is made of lead salts and mixtures of silver, washed with two drops of water and 7-8 drops exhibit potassium chromate solution 2N. At the top is formed of lead yellow zone, below- brown silver zone.Sorption: Pb2+>Ag+.Detection of the ions of mercury(I,II), copper(II), silver(I).In preparing the silver solution mixture taken up in two times greater than the other ions. The pre-column 9 is made of a concentrated solution of alkali to absorb drops, a drop of water, then three drops of a mixture of salts of mercury(I,II), copper, silver. At the top of the yellow band-formed mercury(I,II), then blue - copper brown and the bottom band-silver.

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Sorption: Hg22+>Hg2+>Cu2+>Ag+.

Detection of iron(III) ion, copper(II) and cobalt(II).In column 3 drops of making a mixture of salts of copper ions, iron(III), cobalt, and 2-3 drops of water. At the top of the brown band is formed of iron ions, and then the blue zone of copper ions at the bottom of pink cobalt zone.Sorption:Fe3+>Cu2+>Co2+.Detection permanganate and chromate ions.The column is made of three drops of a mixture of potassium permanganate and chromate, the chromatogram is washed three drops of water. At the top is formed chromate yellow area at the bottom of the pink zone permanganate.Sorption:CrO4

2->MnO4-.

Detection of thiocyanate ions, sulfide, ferrocyanide.The column is made 2 drops of thiocyanate mixture of sulphide and ferrocyanide, 3 drops of water and 3 drops 2N iron(III) salt solution formed three zones: at the top - blue zone (ferrocyanide), then yellow-brown zone (thiocyanate) and at the bottom - the black area (sulfide ).Sorption: [Fe(CN)3]4->CNS->S2-.Write the corresponding reaction equation. Qualitatively determine inorganic ions in the region of their location. Sorption on an aluminum oxide with a number of sorption.Determination of iron(III) ion, copper(II), nickel(II), cobalt(II) and milk meat broth by ion exchange chromatography.Prepare five chromatographic columns. Test solution (milk or meat broth) 1 ml pour into each chromatographic column filled with the sorbent - alumina.Detection of cobalt(II) and nickel(II) ions.№1 column with the sorbent is washed with water, showing a 1% alcoholic solution rubeanic acid formed purple -red zone. Separation does not occur.The column was washed with water №2 exhibit a concentrated ammonia solution (2-3 drops). At the top of the column is shown the pink zone, gradually acquires a brown color characteristic of cobalt ammine, below there is a blue zone ammine nickel.Detection of iron(III) ion, copper(II) and cobalt(II).№3 column was washed with water (3-5 drops). At the top is formed brown color characteristic of the iron ions, and then the blue zone of copper ions at the bottom of the pink zone of cobalt ions.№4 column was washed with 1 -5% solution geksatsiano - II - potassium ferrate authorizing characteristic color with ferric(III) ions.Detection of lead(II) ions.№5 column was washed with water (3-5 drops) and 7-8 drops exhibit potassium chromate solution 2R. A yellow zone of lead compounds.Sketch column derived zones.To draw conclusions about the possibility of detection and separation of inorganic ions in the milk and meat broth by column chromatography.

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