MINISTRY OF SCIENCE AND EDUCATION OF THE REPUBLIC OF
KAZAKHSTAN
STATE UNIVERSITY OF SEMEYnamed after SHAKARIM
Document of SQM
of 3rd level
Edition №1from
«25»02 2015
Ph. P 042-1.02-2015-02
A Laboratory Manualof discipline
on
of«Physical and Colloidal
Chemistry»for lecturer
Natural Science Department
The chair of Chemistry and Geography
A Laboratory Manualof discipline
on
«PHYSICAL AND COLLOIDAL CHEMISTRY»
For the students of 3rd course
For the specialty: 5B011200 – Chemistry
Semey
2015
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Preface
1 WORKED OUT
Compiled by: ______________B.B.Bayakhmetova, Ph.D. in Chemistry, senior
teacher of the Chemistry and Geography Department
2 DISCUSSED
2.1 At the meeting of Chemistry Department
Protocol ___,January___, 2015
Head of the Department ____________ D.R.Ontagarova
2.2 At the meeting of Educational-Methodological Bureau of the Natural Science
Department
Protocol ___, January ___, 2015
Head of the Bureau____________ Z.V.Abdisheva
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CONTENT
1.
1.1.
1.2.
1.3.
Methodical recommendationsfor conductinglaboratory works
Laboratory work# 1. Mollarrefraction
Laboratorywork# 2. Calorimetric measurements
Laboratory work# 3. Studying of homogeneous chemical reaction
equilibrium in solutions
1.4. Laboratory work# 4. Construction of melting diagram of the binary
system: phenol – naphthalene
1.5. Laboratory work# 5.Determination of the rate constant and activation
energy of acetoneiodination reaction
1.6. Laboratory work# 6.Colloid particles. Preparation of iron(III) hydroxide
colloidal solution
1.7. Laboratory work# 7.Adsorption at the liquid-solid interface. Investigation
of adsorption of acetic acid on the activated charcoal
1.8. Laboratory work# 8.Coagulation of sols and studying of their properties
1.9. Laboratory work# 9.Polymers relative molecular masses from viscosity
measurements
1.10.Laboratory work# 10.Isoelectric points
1.11.Laboratory work# 11.Synthesis of emulsion and investigation its properties
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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 theresults in thelab bookthe student mustsubmit the reportteacher.
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Laboratory work#1 The molar refraction
Objectives: An experimental study of refraction additivity.
Equipment: refractometer, pycnometer, analytical balances, capillaries
Reagents: toluene, acetone, benzene, hexane, chloroform, distilled water,alcohol
Procedure: You must to find the density and refractive index of the test
substances fordetermination the specific (molar) refraction. For determination of
densitytest substances, pre-weighed empty pycnometerand filled with water
(dist.),test liquid. Water level was adjusted to the mark in the pycnometer, excess
water removed with filter paper. Next pycnometer weighed on an analytical
balance. The same was done with test liquid. Liquid density (g / cm3) is found by
the formula:

g2  g0
 H O (1.1)
g1  g 0 2
whereg0 -the mass ofthe emptypycnometer(g);
g1,g2-weight
ofthe
pycnometerwith
water
andtest
3
 H 2O -density of waterat a temperature 25 °C (g / cm .);
liquid
(g);
Density isthree timesorisparallel measurementsin severalpycnometerand takethe
arithmetic mean ofup tothree decimal places.
The refractive indexdeterminedusing a refractometer.Measure therefractive
indexand the densityof the liquid atthe sametemperature.Substance is selectedas
directed bythe teacher. The molar refraction is expressed as:
Ïel  RÌ 
n2  1 M

(1.2);
n2  2 
Calculate themolarrefraction(experimental) andcompared with thevalues of
R(theoretical),calculated according tothe additive rule(equation 1.3).Refractionof
atoms and bondsare taken from thetable (see. ''Application''K.).
RÌ   Ratom.   Rbond
( 1.3 )
 Rat – the algebricamount ofrefractionatoms,
 Rbond – the algebricamount ofrefractionbonds
These measurementsare enteredinTable 1
Mass
The mass The mass
Measure of the ofthe
ofthe
Indexofrefr
Density,
ment
emptyp pycnomet pycnomete
action
ρ,g /cm3
ycnom erwith
rwith
(Rat)
eter
the liquid water
RR
Expe The
rime oreti
ntal
cal
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Laboratory work#2 Calorimetric measurements
Determination the solution’s heatof salt
Objectives: Determination of the heat of solution of salt.
Equipment: Bomb calorimeter, Beckman’sthermometer, tubes, glass, volume 400
cm3, weighing-machine.
Reagents: salts- KCl, Na2CO3, CuSO4, CuSO4*5H2O, distilled water.
Procedure: When salts dissolved in the liquid there are proceedstwo processes:
the destruction of the crystal lattice - an endothermic process and ion solvation exothermic process. Depending on the ratio of the thermal effects (which is
determined by the nature of the solute and solvent) heat of solution of salt can be
both: positive H 0 and negative H 0 . Distinguished integral and differential
(partial) heat of solution.
The integral heat of solution - thermal effect dissolving 1 mole of a substance in a
quantity of pure solvent. The differential heat of dissolution - heat effect
dissolving 1 mole of a substance in an infinitely large number of solution. The
concentration of the solution is increased by an infinitesimal amount, which is
neglected.
Calorimetric measurementsdetermined only integral heat of solution. Heatdifferential dissolution are calculated.
The order of performance.For the experiment in the calorimetric glass 10 (see. Fig.
2.1) is poured into 400 cm3 of distilled water. Water accurately weighed (± 1 g)
was determined from the difference of the masses filled and empty glass tube 10. 4
take a sample of dry, well-pulverized salt (± 0,01 g). Hinge for a volume of 400
cm3 is about 5 - 10 g
Figure 2.1.Bomb calorimeter
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1– mixer, 2 – heater, 3 – thermally insulatedcover, 4 – ampoule, 5 – Rubber muff,
6 – electric motor, 7 – holder, 8 –calorimeter glass, 9 – Beckman’s thermometer,
10 – calorimeter cell.
After determination of the constant of the calorimeter temperature
measurements carried out 10 "prior period". Then the tube 4 is removed quickly
with salt and poured through a funnel into the calorimeter salt. The funnel is
removed and the tube was again placed in the calorimeter lid 8. "main period"
ends through experiment 1 - 3 minutes after salt precipitation. This is followed by
10 temperature measurements " final period." The measurement results are entered
into a table 1.
The time of
experiment, min.
prior period
0
…
main period
10
11
…
14
final period
15
…
25
The
Beckman’sthermo
meter reading, 0С
Stop the mixer and dismantle calorimeter. 4 tubes carefully wiped from the
outside of the filter paper and weighed. Dissolved salts accurately weighed (±
0,001 g) is found by the mass difference before and after vials salt precipitation.
According to the plotted tables of which are temperature changes in calorimetric
experiment t x (Figure 2.2)
Figure 2.2 Thegraph oftemperature change during thecalorimetric
experiments.
The specific heat of dissolution integral unknown salt  r H 0 T  calculated
by the equation:
 r H T   Kt x / m
where m - the weight of dissolved salts, g
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Laboratory work#3 Studying of homogeneous chemical reaction equilibrium
in solutions
Objectives: Investigate the effect ofreactant’sconcentration on the chemical
equilibrium.
Equipment:Beaker 100 ml, thermostat, pipette, 4-100 ml Erlenmeyer flask, 4tubes, spoon.
Reagents: Solutions of 0,3M FeCl3 , 0,6M KCNS, salts of KCl, distilled water,
ice.
Procedure: In four test tubes add 1 ml 0,3М of ferric chloride,FeCl3 solution and 1
ml 0,6M KCNSof a solution of potassium thiocyanate. Gentle shaking tubes
stirred solution. All tubes were put stand, one tube with the solution as a control
for comparison.
In solution, there is a reversible reaction:
FeCl3  3KCNS  FeCNS 3  3KCl
Three iron thiocyanate solution according red. In one of the tubes 1 ml0,3M
FeCl3, 1 ml 0,6M KCNSof the other, the third 2-3 micro spatulasalts of KCl. Note
the change in color intensity in each case, comparing the solutions with the
solution of the control tube. The results are recorded in table form.
№ of tube
1
2
3
4
Addedsolution
The direction
Change the color
of displacement
intensity
of
the
(weakening,
equilibrium
strengthening)
(right, left)
1 ml0,3M FeCl3
1 ml 0,6M KCNS
2-3micro spatula
salts of KCl
-
Explain the observed phenomena, and to draw conclusions on the basis of the
principle of LeChatellier.
Laboratory work#4 Construction of melting diagram of the binary system:
phenol – naphthalene
Objectives: Investigateof melting diagram of the binary system. Determination of
the crystallization temperature, building crystallization curves and state diagrams.
Equipment:Thermometer,stopwatch,hotplate, weighing-machine, beakerand
tubes.
Reagents: Phenol-naphthalene,or naphthalene-diphenylamine.
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Procedure: Organic substances have relatively low melting point. For such
systems, thermal analysis can be performed using a conventional thermometer
tubes. In the test tube is poured pure substance or mixture of substances, closed by
a stopper through hole in which the thermometer is inserted. The tube was then
heated in a spirit lamp so that the contents melted. The tube was then transferred to
another, wider tube (air jacket), and every 30 seconds on the stopwatch note the
thermometer. Data directly plotted the coordinate’s temperature - time and get the
cooling curves. The temperature monitoring is stopped after the temperature stops.
Cooling curves to build a scale of 1 degree- 1 mm, 30 mm s-1. Mixtures are
prepared for performance of 10 g (100%) at various ratios of components.
Table 1
Component
1
2
3
4
5
6
7
А
100
80
60
50
40
20
0
В
0
20
40
50
60
80
100
On the basis of experimental data, building the state diagram(melting diagram) in
the coordinates: the crystallization temperature - composition by combining results
characteristic points of the curve.
Report form
№ sample
Course of crystallization (characteristic points)
Startofcrystallization, С
Endofcrystallization, С
1
2
3
4
5
6
7
Test questions
1. Concept phase component, the degree of freedom.
2. Gibbs phase rule.
3. Terms of thermodynamic equilibrium between the phases.
4. Curves cooling crystallization temperature.
5. Thermal analysis, types of fusion diagrams.
Laboratory work#5Determination of the rate constant and activation energy
of acetone
Objectives: Tofamiliarize with methods ofsamplingin the study ofreaction
kineticsto determine the averagerate constant, the activation energy ofthe
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reactioniodinationof acetone.Study the dependence ofthe rate constant forthe
initial concentration ofthe catalyst.
Equipment: Thermostat, beaker 250 ml, 25 ml pipettes, burettes, holder of
burettes, titrimetric flasks.
Reagents:0,1 N I2 in4% solution of KI, solutions of 0,5 N,0,6N , 0,7N
,0,8N,0,9N HCl, 1,0Nacetone, 0,1N NaH𝐶𝑂3 , 0,01N 𝑁𝑎2 𝑆2 𝑂3 , starch solutions
Iodination reaction Acetoneiodinationreactionproceeds according tothe
equation:
CH 3COCH 3  I 2  CH 3CJCH  HJ
The process proceedsautocatalyticallysoacceleratesonereaction products (hydrogen
ions).
Iodinationof
acetoneoccurs
in
two
steps;
1.Reversible reactionenolizationof acetone:
CH 3COCH 3  CH 3COH  CH 2
2. Interaction withiodineenolform:
CH 3COH  CH 2  J 2  CH 3COCH 2 J  H   J 
The first reactionis slow, and the second is rapidly and almostto the end.
Therefore, theprocess speeddetermined by the speedenolizationof acetone, it is
proportional tothe concentration of hydrogenions, but does not dependon the
concentrationof iodine.As a result,the reactionproceeds according tosecondorder.
Procedure::Is offered2 variants ofwork:
The first variant:
1. Carry outthe kineticexperiments attwoT(25 to450C), but aconcentration ofHCI.
2.Calculatethe rate constantof the reaction.
3. Determine theactivation energy.
The second variant:
1. Conduct athreekineticexperienceat constantT, but with different concentrations
ofHCI.
2.Calculatethe rate constantof the reaction.
3.Plot theRNCfromthe initial concentration ofHCI.
Volumetric flask of 250 ml was poured 25 ml of 0.1n iodine solution in 4%
KJ, added 25 mL of 1n HCl (concentration or other directed by the teacher), added
distilled water to make up to the mark was about 20-25 ml and placed in an
incubator. Then simultaneously weighed on the scales measuring tube with a glass
stopper with 10-15 ml of distilled water. Pour into a tube using a pipette 1.5 g of
acetone (density 0.792). Again weighed in the balance and the tube is determined
by the difference between the weights of the exact weight of acetone. Then the
tube was placed with aqueous acetone in the same thermostat and allowed to stand
for 10-15 min, after which the tube contents were poured into a volumetric flask,
rinsed with one or two small portions of distilled water, which also was poured
into a volumetric flask and the volume of the solution was adjusted to the mark
and thoroughly stirred. This time point is considered to start the reaction. The first
sample was taken for analysis immediately after the mixing and stirring of the
reaction mixture, then after an hour the next sample is taken every 30 minutes. 3-4
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more times. Selected 25-ml sample is poured into a conical flask of 100 ml, were
added thereto 25 ml of 0.1n NaНCO3 and titrated with 0.01M Na2S2O3, in the
presence of starch.
The reaction rate constant calculated by iodination acetone equation:
K
C0 H 3O  C0  Cx 
2.3
g
,

 C0  CH 3O
C0 C0H 3O  Cx




(5.1)
Со-wherethe
initial
concentrationof
С0 H O -The initial concentration ofhydronium ions;
Схconcentrationof acetone, unreacted.
acetone;
3
Weighed acetone
 1000, Ì
Ì acetone 250
N 25
С0Н О  HCl (5.3)
250
V0  Vx N Na 2 S 2O3
(5.4)
Cx 
25  2
Ñ0 
acetone
 58,08 (5.2)
3
whereVo -the volume ofNa2S2O3,who had goneto thetitrationat the start ofthe
reactionτ=0;
Vr -volume ofNa2S2O3,who had goneto titrateto a time τ
To calculate theactivation energyuseArrhenius equation:
Е=
𝐾
2,3𝑅𝑇1 𝑇2 𝑙𝑔 2
𝐾1
(𝑇2 −𝑇1 )
R=8,31 J/mol*K
Resultsissueas follows:
The temperature ofexperience...
The initial concentration of...
Theweightedacetone...
№ Timefromstart The
volume Сх,geq-1
of
the ofNa2S2O3,ml
experiment
τ,min.
1
К, geq-1/ min-1
ΔΚ, geq-1/ min1
Test questions:
1. Why isthe reaction rateof iodinationof acetonedoes not dependon the
concentration ofiodine?
2. Whyiodinationreactionof acetonecan be calledautocatalytic?
3. What is thereason for the increasedrate of reactionin the presence ofa
catalyst?
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Laboratory work#6 Colloid particles. Preparation of iron(III)
hydroxide colloidal solution
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Laboratory work#7 Adsorption at the liquid-solid interface. Investigation
of adsorption of acetic acid on the activated charcoal
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Laboratory work#8 Coagulation of sols and studying of their properties
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Laboratory work#9 Isoelectric points
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Laboratory
Polymer’srelativemolecularmassesfromviscositymeasurements
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work#10
Theory
Rheologyisthescienceofflowanddeformationofbodyanddescribestheinterrelatio
nbetweenforce,deformationandtime.Rheologyisapplicabletoallmaterials,fromgase
stosolids.Viscosityisthemeasuredoftheinternalfrictionofafluid.Thisfrictionbecomes
apparentwhenalayeroffluidismadetomoveinrelationtoanotherlayer.Thegreaterthefr
iction,thegreatertheamountofforcerequiredtocausethismovement,whichiscalled“sh
ear”.
Shearingoccurswheneverthefluidisphysicallymovedordistributed,as
in
pouring,spreading,spraying,mixing,etc.Highlyviscousfluids,therefore,requiremore
forcetomovethanlessviscous materials.
Isaac
Newtondefinedviscositybyconsidering
themodel:two
parallelplanesoffluidofequalarea“A”areseparatedbyadistance“dx”andaremovingin
thesamedirectionatdifferentvelocities“v1”and“v2”.Newtonassumedthattheforcereq
uiredmaintainingthisdifferenceinspeedwasproportionaltothedifferenceinspeedthro
ughtheliquid,orvelocitygradient.
Toexpressthis,Newton wrote:
𝐹
𝑑𝑣
=𝜂
𝐴
𝑑𝑦
where
ηisaconstantforagivenmaterialandiscalledits“viscosity”.Thevelocitygradient,dv/dy
,isameasureofthespeedatwhichtheintermediatelayersmovewithrespecttoeachother.It
describestheshearingtheliquidexperiencesandisthuscalled“shearrate”.Thiswillbesy
mbolizedas“D”insubsequentdiscussions.Itsunitofmeasureiscalledthereciprocalseco
nd,s1.ThetermF/Aindicatestheforceperunitarearequiredtoproducetheshearingaction.Itisr
eferredtoas“shearstress”andwillbesymbolizedby“t”.ItsunitofmeasurementsisN/m2
(Newtonpersquaremeter).Using these simplifiedterms,viscositymaybe defined
mathematicallyby this formula:
𝑠ℎ𝑒𝑎𝑟 𝑠𝑡𝑟𝑒𝑠𝑠 𝜏
𝜂 = 𝑣𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦 =
=
𝑠ℎ𝑒𝑎𝑟 𝑟𝑎𝑡𝑒
𝐷
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ThefundamentalunitofviscositymeasurementisthePas,Pascal-seconds.A
materialrequiringashearstressofoneNewtonpersquaremetertoproduceashearrateofonere
ciprocalsecondhasaviscosityofonePas.(Youwillencounterviscositymeasurementsin“ce
ntipoises”(cP),butthesearenotunitsoftheInternationalSystem,SI;onePascalsecondisequaltotenpoise;onemilli-Pascalsecondisequaltoonecentipoises.)Newtonassumedthatallmaterialshave,atagiventempera
ture,aviscositythatisindependentoftheshearrate.Inotherwordstwicetheforcewouldmovet
hefluidtwiceasfast.
Viscositiesofdilutecolloidsolutions.Formostpureliquidsandformanysolutionsanddis
persionsη isa well defined quantity for a giventemperatureand pressure which
isindependentoftanddv/dx,providedthattheflowisstreamlined(i.e.laminar).Formanyothe
rsolutionsanddispersions,especiallyifconcentratedand/oriftheparticlesareasymmetric,d
eviationsfromNewtonianflowareobserved.ThemaincausesofnonNewtonianflowaretheformationofastructurethroughoutthesystemandorientationofasym
metricparticles causedby the velocity gradient. Capillaryflow methods
Themostfrequentlyemployedmethodsformeasuringviscositiesisbasedonflowthrough
acapillarytube.Thepressureunderwhichtheliquidflowsfurnishestheshearingstress.There
lativeviscositiesoftwoliquidscanbedeterminedbyusingasimpleOstwaldviscometer.(Fig
ure1).10mLliquidisintroducedintotheviscometer.LiquidisthendrawnupintotherighthandlimbuntiltheliquidlevelsareaboveA.Theliquidisthenreleasedandthetime,t(s)forther
ight-handmeniscustopassbetweenthemarksAandBismeasured.Forasolutionthe relative
viscosity:
𝜂
𝑡
𝜂𝑟𝑒𝑙 = = 𝜂𝑠𝑝𝑒𝑐 = 𝜂𝑟𝑒𝑙 − 1 (1)
𝜂0
𝑡0
wheretandt0theflowingtimeforsolutionandsolventinsecond,respectively,η 0 andη
viscosityofpuresolventandsolution.Thespecificincreaseinrelativeviscosityorincrement:
ηspec=ηrel-1.Thereducedviscosity(orviscositynumber):ηspec/c.Theintrinsicviscosity(or
limiting viscosity number):
[𝜂] = lim
𝑐−0
𝜂𝑠𝑝𝑒𝑐
𝑐
lim
𝑐−0
𝑙𝑛𝜂𝑟𝑒𝑙
𝑐
(2)
Fromexpressionsitcanbeseenthatthereducedviscositieshavetheunitofreciprocalconce
ntration.Whenconsideringparticleshapeandsolvation,concentration
isgenerallyexpressedintermsofthefractionoftheparticles(ml/mlorg/g)andthecorrespond
ingreducedandintrinsicviscositiesare,therefore dimensionless.
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Sphericalparticles.Einsteinmadeahydrodynamiccalculationrelatingtothedisturba
nceoftheflowlineswhenidentical,noninteracting,rigid,sphericalparticlesaredispersedina
liquidmedium,
andarrivedattheexpression:η=η0(1+2.5ϕ).Theeffectofsuch
particlesontheviscosityofdispersiondepends,therefore,onlyonthevolumewhichtheyo
ccupyandisindependentoftheirsize.Forinteracting,non-rigid,solvatedornonsphericalparticlestheEinsteinformisnotapplicablebecausetheviscositydependsonthes
eparameters.Viscositymeasurementscannotbe usedtodistinguish between particles of
different
size
but
of
thesameshapeanddegreeofsolvation.However,iftheshapeand/orsolvationfactoralters
with
particlesize,viscositymeasurementscanbeusedfordeterminationparticlesize(formolar
mass).Theintrinsicviscosityofapolymersolutionis,inturn,proportionaltotheaverageso
lvationfactorofthepolymercoils.Formostlinearhighpolymersinsolutionthechainsares
omewhatmoreextendedthanrandom,andtherelationbetweenintrinsicviscosityandrelat
ivemolecularmasscanbeexpressedbygeneralequationproposedbymarkandHouwink:
𝛼
[𝜂] = 𝐾 𝑀𝑣𝑖𝑠𝑐
(3)
whereKandα
arecharacteristicofthepolymer
solventsystem.Alphadependsontheconfiguration(stiffness)ofpolymerchains.Inviewo
fexperimentalsimplicityandaccuracy,viscositymeasurementsareextremelyusefulforr
outinemolarmassdeterminationsonaparticularpolymersolventsystem.Kandalfaforthesystemaredeterminedbymeasuringtheintrinsicviscositi
esofpolymerfractionsforwhichtherelativemolecularmasseshavebeendeterminedinde
pendently,e.g.byosmoticpressure,sedimentationorlightscattering.Forpolydisperseds
ystemsanaveragerelativemolarmassintermediatebetweennumberaverage(alpha=0)
and mass average(alpha=1)usuallyresults:
∑ 𝑀𝛼+1 𝑑𝑁
𝑀𝑣𝑖𝑠𝑐 = [
]
∑ 𝑀 𝑑𝑁
Equipment:Ostwald viscometer, beaker, volumetric flask, pipette
Reagents: 0.5 g/mL aqueousstock solution of PVA.
Experimentalprocedure
Prepareconcentrationseriesofpoly-vinyl-alcohol:0,0.01,0.02,0.03,0.04,0.05gcm3.Use1010mlfromeachsolventforthemeasurement,startwiththesolventandgoonfromthemostd
ilutedtothemoreconcentratedsolutions.Determinetherelativeviscositiesofsolutions
byusing Ostwaldviscometer.
Tabularthedataandplotη spec/candlnηrel/cagainstconcentration.Determinetheintrinsi
cviscositywithextrapolationofthecurvesasFigure2shows.CalculatethemolarmassbyE
quation3,K=0.018anda=0.73forPVA.
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Figure 1.Ostwald viscometer.
Determination of the limiting viscosity numberbyextrapolationc→0 of
𝜂
𝑡
reducedviscosity concentrationcurves𝜂𝑟𝑒𝑙 = = 𝜂𝑠𝑝𝑒𝑐 = 𝜂𝑟𝑒𝑙 − 1
𝜂0
𝑡0
Calculationofresults
c (gcm-3)
0
t(s)
t(s)
t(s)
taverage(s)
ηrel
ηspec
0.01
0.02
0.03
0.04
0.05
Reviewquestions
Rheologicalclassification ofmaterials.The ideal chain
mathematicmodelforlinearpolymer.
ηspec/c
(lnηrel)/c
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Laboratory work#11 Synthesis of emulsion and investigation its properties
Objectives: Preparation and use of type dilute emulsions; phase inversion
emulsion benzene - water.
Equipment: Flasks 100 ml with the ground-in traffic jams, microscope, subject
glass, pipettes, glasses.
Reagents: 3% solution of oleate of sodium, benzene, the concentrated calcium
chloride
solution,
dyes-Sudan-III
and
the
methylene
blue.
Procedure: Take two 100 ml flask with ground glass stoppers, poured into 10 ml
of a 3% - sodium oleatesaturatedsolution in water and 10 ml of benzene was
stained by Sudan III. In the absence of Sudan III, using methylene blue, which
change color ofwater.Into another flask was poured 19 ml of distilled water and 10
ml of benzene. Both the flask sealed and shaken vigorously until a homogenous
emulsion. Then the two flasks are left alone for a while. In the first flask emulsion
remains stable in the second there is a rapid separation of liquids (emulsion
breaking).
Give explanation of the different stability of the obtained emulsion.
To determine the type of emulsion formed from the flask in which no separation
was placed a drop on a glass slide (while avoiding foam) is determined under a
microscope and it is colored.
Type of emulsion can also be defined by the merger drops. To the residue in the
same emulsion of the flask are poured several drops of a concentrated solution of
calcium chloride. Flask thoroughly shaken and determine the type of emulsion
under a microscope.
The report schema structure is necessary to draw the obtained emulsions in both
cases, showing the orientation of the molecules of the emulsifier at the interface
between the dispersed phase and the dispersion medium.
Test questions
1.What systemsare referred toMicro heterogeneous? What is common tothemwith
colloidalsystems?
2. What is anemulsion? What is theirclassification?
3. What explains the instability ofthe emulsion?
4. What are the requirements to the emulsion?
5. Drawlayoutemulsifier dispersed dropletphase in theO / W emulsionandW / O.
6.What is theessence ofthe phenomenon ofphase inversionemulsion?
7. What are the methods for determining thetype of emulsion?
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Ph. P 042-1.02-2015-02
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