MINISTRY OF SCIENCE AND EDUCATION OF THE REPUBLIC OF KAZAKHSTAN
STATE UNIVERSITY OF SEMEY named after SHAKARIM
Methodical recommendationsfor conductinglaboratory works
« PHYSICAL AND COLLOIDAL CHEMISTRY »
for the specialty
5B011200– «Chemistry»
Semey -2015
LABORATORY WORKS
Methodical recommendationsfor conductinglaboratory works
Laboratory studiespromotesknowledge of thephysical methods ofchemical research,the studentdevelopsindependence andinstillsthe skillsof the experiment.In order towork in the laboratorytook placesuccessfully,you must firstexplorethe theoretical materialfrom textbooks, lecture notesand thebenefitsof chemicalworkshops. Thisproducesa conscious attitude tothe implementationof experimental techniques, the work itselfwill beunderstood,and, therefore,and understood.Working in thechemistry labshouldstrictly observe thesafety rulesand regulationsofthe chemicalutensils andappliances.We must learnto usechemical agents, chemical equipment,which are listedin the guidelinesfor the workon the chemicalworkshop. Guidelinesshould not bea straitjacket, and to depriveindependence,but ratherfollow the orders ofspeeds up, prevents possibledamage toequipment,glasswareand reagents.The success of theexperimental workdepends notonly on thecorrectness of the choiceof working methods,the sequenceof measurement, weight measurements, but also on the correctsystematic recording ofresults.By theimplementation ofthe laboratory workallowedstudents withadmissionafter verification ofa teacherof theoretical knowledgeon the subject, knowledge of laboratorymethodsof workand preparedto conductlab journalentrieson the topic.After completingthe laboratory workthe student mustbring order toyour workplaceand deliver themon dutyortechnician. After processing there sults in the lab book the student must submit the report teacher.
Laboratory work№ 1
Subject:Mollarrefraction
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 solutions / N solutions / N reference solution / The sugar concentration in the test solutionReport 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 solution
3. Fill in the table.
Laboratory work №2
Subject: "Determination of the heat of the dissolution of salt."
Equipment and materials: glass vessel with stirrer or a Dewar flask of 0.5 liters; glass of 0.5 l; Beckmann thermometer; ampoule for salt; glass rod; analytical balances; porcelain mortar; technical scales; hourglass for 1 minute; KNO3; CuSO4*5H2O; anhydrous CuSO4
Method of implementation:
Collects the device as described below. It weighs approximately 8 grams of copper sulfate and placed it in a vial (ampoule). Calculate how much anhydrous salt and water contained in the capture of rigging. In a pre-weighed beaker was poured 300 g of water, and weighed again to within 0.01 g Since the dissolution of copper sulphate to the absorption of heat occurs, then a Beckman thermometer is adjusted so that the meniscus of the mercury was in the top of the scale. Insert tube (vial) with the salt in the container lid. Determine the temperature change in the preliminary, main and final periods and the graph are the corrected temperature change when the salt is dissolved.
9-10 triturated g copper sulfate are placed in a porcelain dish and heated with stirring until until a white powder of the anhydrous salt. Last pour into a test tube, which immediately closed with a rubber stopper. After cooling, take a sample of the anhydrous salt equal to g and the change in temperature is determined as described above, by dissolving it in 300 g water.
Taking into account that the dissolution of copper sulphate heat is released, a Beckman thermometer is adjusted so that the meniscus of the mercury thermometer was at the bottom of the scale.
According to the found value of the calorimeter constant K and calculate the result of the experience of the warmth of the dissolution of anhydrous salts and crystalline according to the formula:
Qdis=K∆tv
To be able to compare their results with the reference heat of solution data necessary to calculate the amount of water (mol) per 1 mole of salt.
The heat of formation Q of hydrate crystals from the aqueous salt is calculated by the following equation:
Q=Qwat - Qcrist
The form results:
KNO3 / CuSO4 / CuSO4*5H2OMass of the empty tubes
#tube with salt
#salt
#Dewar
#vessel with water
#water
Measurements (range 0.5 min)
1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10Water temperature
#solution KNO3
#the water in the calorimeter
#solution CuSO4
#the water in the calorimeter
#solution CuSO4*5H2O
Laboratory work №3
Subject: «Determination of neutralization heat».
Equipment and materials: device for determining the thermal effects (calorimeter); vial for infusion of alkali; 10% solution KOH; 10% solution HCl; NaOH; CH3COOH (Ice).
Method of implementation:
Determination of the heat of neutralization of a weak acid with a strong base collected calorimeter. The plug calorimeter, in addition to the agitator and thermometer Beckman inserted vial alkali.
The neutralization reaction is accompanied by release of heat; therefore Beckman thermometer is preset so that the mercury in the beginning of the experiment was in the lower part of the thermometer scale capillary. After you have assembled calorimeter, determine its constant inserting into the lid of the calorimeter empty vial.
After defining the constant calorimeter proceed to the determination of the heat of neutralization.
6 g of glacial acetic acid are introduced into a volumetric flask of 500 ml, previously weighed to the nearest 0.1 g (mass g1). Acid then diluted with distilled water to the mark. The acid bring to room temperature and weighed flask containing solution (mass g2).By finding the difference of weight of the solution g=g2 – g1; acid was poured into the calorimeter.
In technical balance weighed 4 g NaOH (solid) is introduced into a volumetric flask of 50 ml, and adding small portions of distilled water, dissolved, cooling the solution. Dilute to the mark with liquid and cooled to room temperature.
Laboratory work №4.
Subject: "Determination of the heat of hydration of salt."
Methods of implementation
To determine the weighted sample taken two crystalline mass, 7.5 g sample of crystalline first used to determine the heat transfer in the second and chinaware, and to obtain an anhydrous salt (until the disappearance of blue color) is heated. The resulting anhydrous salt is transferred to a pre-weighed probirkui quickly zakryvayutee rubber stopper. After cooling, the tube was weighed. To take CuSO4 300 g of water, and for CuSO4*H2O - 297 g.
Determination of heat of hydration salt corresponds to the definition of neutralization heat.
Solution / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10CuSO4
CuSO4*H2O
Laboratory work № 5
Subject: "Thermal analysis naphthalene, phenol system."
Equipment and Reagents: naphthalene, phenol, tubes, stoppers, thermometer, wire stirrer, a tripod, capacity 500 ml.
Methods of implementation.
At seven tubes is poured on 8 g of the following composition:
Components of the mixture / The amount of the mixture (d) in vitro1 / 2 / 3 / 4 / 5 / 6 / 7
Naphthalene / 8 / 6 / 5 / 4 / 3 / 2 / 0
Phenol / 0 / 2 / 3 / 4 / 5 / 6 / 8
The vials are stoppered with mixtures through which to 100C thermometer and agitator the wire and mounted on a tripod. In a 500 ml beaker is heated to boiling and the water is lowered to one of the tubes with the substance. When the material is melted and heated to 100 ° C, the tube is wiped dry with a towel and strengthen in the air shirt.
Laboratory work №6
Subject: "Measuring the acetic acid adsorption on the carbon surface of the animal."
Equipment and Reagents: six 250 ml flasks with corks; Six conical flasks of 150 ml; pipette 50, 25, 10, 5ml; 50 ml burette graduated in 0.1 ml; six funnels for filtration; filter paper; animal black; 2M CH3COOH solutions; 0.1 M NaOH Phenolphthalein (indicator).
Methods of implementation.
Dilution with 2 M acetic acid solution is prepared in six flasks approximately the following concentrations solutions and in the amounts indicated in the table:
1 / 2 / 3 / 4 / 5 / 6The amount of solution in ml / 150 / 150 / 150 / 125 / 110 / 105
Concentration, mol / ml / 0,012 / 0,025 / 0,05 / 0,1 / 0,2 / 0,4
The exact content of acetic acid was determined by titration with 0.1M NaOH solution (fenolftalein - indicator), and from the flasks №1, 2 and 3 are selected by pipette 50 ml of the flask №4 - 25 ml of the flask №5 - 10 ml, and the flask №6 - 5 ml. Into each flask was introduced 3 g of animal charcoal. Then all thoroughly shaken flasks for 10 min. Filtered separately the contents of each flask through the filter paper. Selecting a sample pipetted from the filtrates in the same amounts, which have been taken for the initial titration, the concentration is determined by titration with acetic acid. The difference between the first and second titration (after conversion to 100 ml) of acetic acid gives the number x, 3 g of charcoal absorption of 100 ml.
Acetic acid solution by titration to determine its carbon adding initial concentration C, based on the milliliters of 0.1 M sodium hydroxide solution and the filtrate titration - its concentration C1 after adsorption:
x = C – C1
The results are plotted on a graph, and the x-axis is applied to the value of C1 and the ordinate - the value xm where m - mass of the absorber. The resulting curve is the adsorption isotherm. To determine the value of a graphic and n, as noted above, are plotted on the abscissa, the values of lg C1 - the ordinate. Found points must lie on a straight line.
Measure the value of the tangent of the angle of the line to the horizontal axis, which gives the value n. The distance from the point of intersection of the line y-axis from the origin corresponds to the value of lg a.
number flasks / approximate concentration / C / C1 / C-C1=x / xm / lg C1 / lgxm1
2
3
4
5
6
1