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    DEPARTMENT OF

    CHEMISTRY

    PHYSICAL CHEMISTRYLABORATORY

    CHEMISTRY 444/544LABORATORY MANUAL:

    WINTER, 2011

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    CONTENTSPage No

    Occupational Health and Safety 3

    Laboratory Rules and Regulations 4General ire Orders !"c#no$ledge%ent or% &"rrange%ents for Laboratory Sessions 'Reading References 1(Plagiaris%1)Laboratory Reports or%at13

    Expe!"e#$%

    1 *inetics of reaction bet$een e+,,,- and SN/ by the stopped 0o$

    techniue 12

    2 &!'($!)#(*+R)$($!)#(* %pe$( )- HC* (#. DC*

    2

    Te").#("!% )- 3(*(#! e**%

    4 eter%ination of heats of solution fro% solubility %easure%ents

    3!

    5 Te p($!$!)# )e!e#$ 6 Te e78!*!'!8" I+9 I2 I+

    ; M(3#e$! %8%ep$!'!*!$ )- %)*!. $(#%!$!)# "e$(* )"p)8#.%

    41

    & he dipole %o%ent of chloroben5ene44

    ' 6iscosity7 8olar %ass of a poly%er

    4'

    2 9nthalpy of %i:ing of acetone and $ater

    ;3

    1( 6iscosity of gases ;&

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    11 issociation constant of H3OOH fro% electrical conducti

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    1; Ce"!(* O%!**($!)#%: Te Be*)8%)+>(')$!#%?!! Re($!)#

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    OCCUPATIONAL HEALTH AND SAFETY

    YOUare $arned that all substances handled and all operations perfor%ed

    in a laboratory can be ha5ardous or potentially ha5ardous. "ll substances

    %ust be handled $ith care and disposed of according to laid do$n

    procedures. "ll operations and %anipulations %ust be carried out in an

    organised and attenti

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    LABORATORY RULES AND RE@ULATIONS

    1 Students %ust be present ten %inutes before the start of each

    scheduled laboratory session. Lateco%ers $ill be refused entry to

    the laboratory.

    ) No student $ill be per%itted to $or# in the laboratory outside of

    laboratory hours e:cept by e:press per%ission of the staB

    %e%ber+s- responsible for the session. Ne

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    %ust be returned to its proper place= clean and dry= and in $or#ing

    condition= unless other$ise indicated or instructed.

    11 "ll solids %ust be discarded into the bins pro

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    )1 he use of reagent bottle caps as $eighing receptacles is forbidden.

    )) Liuids @ $hether corrosi

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    O# e(!#3 ( e e(8($!)# (*("

    1 Stop nor%al $or# i%%ediately.

    ) 8a#e safe any apparatus= and %aterial in use= shutting oB as

    necessary any local gas taps?

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    9P"R89N O H98,SR>

    PORL"N S"9 EN,69RS,>

    ACNOWLED@EMENT FORM

    ,= the undersigned +please print full na%e-

    ..........................................................................

    Student No. ........................................

    ,dentity No. .......................................

    do hereby ac#no$ledge ha

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    ARRAN@EMENTS FOR LABORATORY SESSIONS

    D($e% (#. T!"e% -) P($!(* Se%%!)#%

    Practical sessions $ill be held only on the speciAc ti%etabled day during

    the $inter uarter.

    Laboratory sessions $ill co%%ence pro%ptly. Students are e:pected to

    report punctually for each laboratory session. hose arri

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    they can still ha

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    des#- and utilise the full area of the sheet of graph paper= adKusting the

    scales on the a:es to %a:i%i5e the space a

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    Garland= Nibler and Shoe%a#er= Experiments in Physical Chemistry=

    Se

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    L(')($) Rep)$%:

    Lab reports %ust be $ritten INDI&IDUALLY= %ust be of Kournal uality=

    and %ust follo$ the M"S for%at. Online you can also And guidelines onhttp7??$$$.rose@hul%an.edu?tilstra?.

    I"p)$(#$ D($e%: o be ad

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    o ecide $hich

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    iscussion

    onclusion

    References

    he follo$ing pages include a %ore detailed description of each of thesections. Ce a$are that this is a li

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    literature= and identify ho$ this $or# is diBerent or related to the citedliterature.

    he concepts and their related euations %ust be de

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    practice constructing one fro% scratch. he construction of a good datatable reuires #no$ing $hat the i%portant features are.

    ,. We# $) 8%e T('*e%

    ables are to be used $hen the data are precise nu%bers= $hen there aretoo %any to be presented clearly in the narrati

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    Often the %ost concise and precise $ay to present data is to plot it. hechallenge is #no$ing $hat to plot on $hich a:is. "n understanding of thetheory behind the e:peri%ent should pro

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    ,n the discussion section= it should be clearly stated $hether or not theproble% has been resol

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    EPERIMENT 1

    THE INETICS OF REACTION BETWEEN IRONIII AND

    THIOCYANATE IONS BY THE STOPPED FLOW TECHNIGUE

    Re-ee#e7 "t#ins= Physical Chemistry= &th 9d.= pp. '!4@'!!.

    he rates of reaction of %etal auo ions $ith ligands ha

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    +*OHZ 1.'! : 1(@3 8 *OHZ !.; : 1(@; 8 *c Z #1)?#)1Z 123 8@1 all

    %easured at ); -

    V*cZ #34?#43X

    Note that the reaction+s- that $e are studying are the for$ard paths of the

    euilibria. Note also that there are t$o substitutions to consider in the%echanis%= that is= of the auo ion and of the %onohydro:y auo ion= and

    further= that the euilibria are connected by hydrolysis constants. 6alues

    for these euilibriu% constants can be obtained fro% the literature.

    his leads to the second factor to be considered in the e:peri%ent. De

    need to #eep the ionic strength constant +(.; 8 here-. ,t is usual to

    %aintain ionic strength $ith salts such as NalO4and LilO4= and to adKust

    the acidity $ith an acid such as HlO4. Ob

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    (.1( 8 HlO49 1.( 8 NalO4

    he accurate concentrations of these solutions are gi

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    igure ) sho$s the positions of the

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    On the S"@)( Rapid *inetics "ccessory the dead

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    F!38e 1: Sche%atic of the Hi@ech S"@)( Rapid *inetics "ccessory.

    );

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    !#e$! (#(*%!%

    Since the position of the euilibriu% connecting the eSN)W and

    e+OH-SNWspecies lies far o

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    Rate of destruction of eSNW Z ][][

    1 3412 FeSCN

    H

    Kkk

    K

    OH

    c

    +

    he nett rate of for%ation of eSN)W

    is gi

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    V!eXeV"CNXe Z ec

    FeSCNK

    ][1

    leading to cancellation of the Arst and third ter%s abo

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    9:peri%ent ).

    &IBRATIONAL+ROTATIONAL SPECTRA OF HC* (#. DC*

    Expe!"e#$ < p(3e 41; !# S)e"(?e, e$ (*, $ e.!$!)#

    9uip%ent +in )11C-7lecture bottles of Hl and l,R sa%ple cellglass

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    +to a dis#ette or to the H98 Aleser

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    ,nstructions7

    he FSpectru% for Dindo$sF +SD- soft$are pac#age controls the Per#in@9l%er %odel 1!(( ,R and is running on a P connected to theinstru%ent.

    he data collection co%puter should be po$ered on and SD $ill startauto%atically after Dindo$s2; is loaded. Other$ise= SD can be startedby double clic#ing on the FSpectru%F des#top icon. he user log in dialogbo: $ill be displayed. Log in to the progra% as F144F= $hich can beselected fro% the list of users in the pull do$n %enu. he pass$ord isFpche%F. ,f the progra% is already running= go to the FSetupF %enu= selectFhange loginF and select F144F fro% the users %enu.Place the e%pty ,R cell into the sa%ple co%part%ent by sliding the endplate of the cell into the %ount inside the co%part%ent. lose the sa%pleco%part%ent door.

    he Spectru% %ain $indo$ loo#s li#e7

    "fter the e%pty cell is properly positioned in the instru%ent sa%pleco%part%ent= clic# on the FC#GrdF button +on the upper toolbar- to collecta bac#ground spectru%. he scan para%eters ha

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    the bac#ground spectru%. Must use the default na%e and selectFOou can then FloseF the selected spectru% fro% the FileF%enu. +Note7 if you FhaltedF a pre

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    H98 net$or# Aleser

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    Expe!"e#$

    her%odyna%ics of Gal

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    ( ) ( ) ( ) ( ) ( )3 4 2

    6 62 2Zn Fe CN aq Fe CN aq Zn aq

    ++ +

    or this reaction the Nernst euation +euation 1- beco%es

    ( )

    ( )

    2 4

    6

    3

    6

    2

    2ln

    Zn Fe CNo

    Fe CN

    A ART

    nFA

    +

    =

    ,f $e assu%e that the acti

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    he 5inc electrode is a 1@c% $ide strip of 5inc sheet and theplatinu% electrode should be constructed by attaching a s%all piece ofplatinu% foil to the tip of the electrode. ,nterface the t$o electrodes to theco%puter

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    Expe!"e#$ 4

    HEAT OF SOLUTION FROM MEASUREMENTS OF SOLUBILITY

    Re-ee#e%: "t#ins and de Paula= pp. 42@;4= )1)@)14.

    Ma%es and Prichard= pp. !)@!4.

    I#$).8$!)#:

    One of the best #no$n and %ost useful ther%odyna%ic for%ulae is the

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    he ther%ostat should be set at about 4( $hen you enter the

    laboratory. " bottle containing a saturated solution of ben5oic acid and

    e:cess solid ben5oic acid $ill be supplied. Sha#e the bottle and transfer

    about 1;( c%3to the conical 0as# supplied. he solution should contain a

    fe$ gra%s of undissol

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    ,s the signof1Hoin accord $ith Le hateliers principleQ iscuss.

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    he *, and *,3are insoluble in he:ane. he purpose of the e:peri%ent is

    to deter%ine the euilibriu% constant of the abo

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    +ii- he tip of the pipette %ust pass throughthe he:ane layer to reach

    the aueous layer. o pre

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    EPERIMENT ;

    MA@NETIC SUSCEPTIBILITY OF SOLID TRANSITION METAL

    COMPOUNDS

    Re-ee#e%7 . Nicholls= Complexes o the !irst/6o8 Transition

    Elements= pp. 1((@111.

    .P. Shoe%a#er= .D. Garland= M.D. Nibler= Experiments in

    Physical Chemistry= 'th 9d.= pp. 3!1 @ 3&(.

    ,f a substance is placed in a %agnetic Aeld= the %agnetic Aeld strength

    $ithin the substance $ill either be greater or s%aller than that in the

    surrounding space. ,f the intensity is greater= the substance is said to be

    p(("(3#e$! $hile if it is s%aller the substance is .!("(3#e$!.

    ia%agnetis% is uni

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    %o%ent= =of the substance by Lange

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    also=

    $here $# and $u represent the $eights of the #no$n and un#no$nsubstances respecti

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    the hole through the bench= call the lecturer or de%onstrator= $ho $ill

    attend to this.

    4 Re%o

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    EPERIMENT ENE

    Re-ee#e7 "t#ins= Physical Chemistry= &th 9d.= pp. !'!@!2!.

    " dipole is produced $hen there is an asy%%etric distribution of charge

    o

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    %olar polari5ability= P= is gi

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    he theory of ebye assu%es that polar %olecules are suciently separated

    so that the interaction a%ong their dipoles is negligible. his condition can

    only be obtained in the gas phase or in dilute solutions in a non@polar

    sol

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    and of pure cyclohe:ane. Note the a%bient te%perature.

    I#%$8"e#$($!)#

    9ach student is pro

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    EPERIMENT

    &ISCOSITY: THE MOLAR MASS OF A POLYMER

    Re-ee#e%7 Ma%es and Prichard= Practical Physical Chemistry= 3rd 9d.=

    pp. )3@);= pp. ;2@!(.

    "t#ins= Physical Chemistry= &th 9d.= pp. &4'@&;(.

    ,f a shearing force is applied to a liuid= the liuid $ill 0o$= but at the sa%e

    ti%e a resistance to this 0o$ $ill be set up. onsider a liuid 0o$ing along acapillary tube. ,t has been fairly $ell established that= if the rate of 0o$ is

    not too great= the liuid in i%%ediate contact $ith the $all of the capillary is

    stationary. he rate of 0o$ increases $ith the distance fro% the $all. Let

    the distance fro% the $all be 5 and the

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    radius r in a ti%e t. P is the pressure diBerence across the t$o ends of the

    tube= $hich causes the 0o$.

    ,n practice the capillary tube is incorporated in a

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    %olecules %a#e a relati

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    $here m and a +see abo

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    since P depends only on the density of the liuid.

    ,n this case the densities can all be ta#en as that of $ater and $e ha

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    EPERIMENT

    ENTHALPY OF MIIN@ OF ACETONE AND WATER

    Re-ee#e7 "t#ins= Physical Chemistry= &th 9d.= pp. 1&3@1&4.

    he %olar enthalpy of %i:ing= H%:g?+n"W nC- of t$o liuids " and C to for%a liuid %i:ture= can be deAned as the enthalpy change acco%panying the

    for%ation of 1 %ole of the liuid %i:ture fro% the reuisite a%ounts of the

    t$o pure liuid co%ponents at the sa%e te%perature and pressure as the

    %i:ture.

    ,n this e:peri%ent the %olar enthalpies of %i:ing of

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    upon $hether the %i:ing process is e:other%ic or endother%ic=

    respecti

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    as abscissa. Moin the plotted points. he Agure obtained %ay loo#

    %ore or less as follo$s7

    Note that= in contrast to the situation encountered in the heat of

    %i:ing e:peri%ent described in part +a-= the electrical heating

    e:tends o

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    C(*8*($!)#%

    +a- Calculations o heat capacity

    ,f the potential diBerence applied to the heater is denoted F6F= the

    current FiF= and the ti%e for $hich the heater $as acti

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    EPERIMENT 10

    &ISCOSITY OF @ASES

    Re-ee#e%7 .P. Shoe%a#er= .D. Garland= M.,. Steinfeld= M.D. Nibler=

    Experiments in Physical Chemistry= 'th 9d.= pp. 1)'@13;.

    "t#ins= Physical Chemistry= &th 9d.= pp. '3(@'3).

    ,n this e:peri%ent= the

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    rises fro% a lo$er Aducial %ar# ato an upper Aducial %ar# bis denoted as

    tab. or any such apparatus of gi

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    R*74

    1' =

    +3-

    Since euation +1- does not apply accurately $ithin this transition region=it is necessary that < should be s%all in co%parison $ith

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    9:a%ination of the apparatus to deter%ine the nature of the

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    D($(

    1 Poise Z (.1 N s %@)

    L Z 1;.( c%

    r Z (.(&; %%

    EPERIMENT 11

    DISSOCIATION CONSTANT OF ACETIC ACID FROM

    MEASUREMENTS OF ELECTRICAL CONDUCTI&ITY

    Re-ee#e%: "t#ins and de Paula= pp. &!1@&!4.

    Ma%es and Prichard= pp. )32@)43.

    De#!$!)# )- Te"%:

    Resistance +R-

    ,f a potential diBerence= 6= is applied bet$een t$o points in a conductor=

    and an electric current= i= 0o$s through the conductor= the electrical

    resistance is deAned as R Z 6?i.

    Enits7 oh%=

    onductance +G-he conductance is deAned as the reciprocal of resistance= i.e. G Z l?R.

    Enits7 sie%ens= S

    Resisti

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    c$

    =

    $here c is the concentration $hich %ust be e:pressed in %ol % 3in order

    to obtain

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    electrodes and " the area of the electrodes. his can be $ritten Z G$here is called the cell constant since it depends on the di%ensions ofeach indi

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    concentration c and at inAnite dilution= respecti

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    increases.

    Expe!"e#$(* P)e.8e:

    8a#e up solutions of (.() %ol d% @3= (.(() %ol d%@3and (.((() %ol d%@3

    acetic acid fro% the (.1 %ol d% @3acid. his is %ost con

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    Expe!"e#$ 12

    THE RATE OF HYDROLYSIS OR IN&ERSION OF SUCROSE,

    BY POLARIMETRY

    Re-ee#e%: "t#ins and de Paula= pp. &21@'(3.

    Ma%es and Prichard= pp. ''@'2 and 122@)((.

    I#$).8$!)#:

    irst@Order Reactions

    he hydrolysis of sucrose occurring in aueous solution can be $ritten as

    the reaction

    1)H))O11 W H)O +& !H1)O! W !H1)O!sucrose @glucose @fructose

    $hich proceeds

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    .....+3-

    9uations +)- and +3- are

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    facing the light source= the light is said to be right circularly polari5ed light.

    ,f it rotates countercloc#$ise= it is left circularly polari5ed light. Dhen left

    and right circularly polari5ed bea%s of eual intensity are co%bined= they

    yield plane polari5ed light. on

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    " liuid or a solution sho$s optical acti

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    $here k= 6 and l are as deAned pre

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    place at roo% te%perature. Record the te%perature.

    3. ill the polari%eter tubes by using a pipette. ry the tube carefully

    before inserting into the polari%eter. 8a#e sure that no air bubbles

    are present in the tube.

    4. Since solid sucrose is rather hygroscopic= close the reagent bottle

    after use.

    ;. lean the polari%eter tube after use by rinsing it three ti%es $ith

    distilled $ater. ry the tube on the outside.

    G8e%$!)#%:

    1. Dhat is the role of HWin this reactionQ Dhat is the

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    EPERIMENT 1

    A COMPLE REACTION 6 THE BROMINATION OF ACETONE

    Re-ee#e: . aniels= M.D. Dillia%s= P. Cender= R.". "lberty= ..

    orn$all= M.9. Harri%an= Experimental Physical Chemistry= &th

    edition= pp. 1;)@1;;.

    I#$).8$!)#:

    he purpose of this e:peri%ent is to deter%ine the rate la$ and the rate

    constant for the bro%ination of acetone. ro% rate data collected at t$o

    or %ore te%peratures the acti

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    e:tent of reaction. he s%all a%ount of bro%ine is co%pletely consu%ed

    $hile the other reactants re%ain at an essentially constant concentration.

    Since the reaction (*atep III=

    +!-

    he e:ponent r is deter%ined fro% t$o runs= say , and ,,,= in $hich

    VH3OH3X, Z VH3OH3X,,,and VHWX,,,Z $VHWX,. hese conditions lead to

    ()lo>

    )8*ate(*atelo>* IIII=

    +&-

    he rate constant is then deter%ined according to euation +)- fro% the

    e:ponents= reaction rate= and the concentration data for $hich the rate

    applies.

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    he acti

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    absorbance. Repeat this procedure by using Arst !.( c%3and then 3.( c%3

    of (.() %ol d%@3Cr)diluted in each case $ith 1(.( c%3of 1 %ol d%@3Hl

    and sucient distilled $ater to gi

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    ion. "n analogous euation is used along $ith the data on solutions

    nu%ber 1 and 4 to calculate the order $ith respect to bro%ine.

    Ese euation +3- and the e:peri%ental results obtained to calculate the

    rate constant # for each of the #inetic runs. eter%ine an a

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    Expe!"e#$ 14

    DISSOCIATION CONSTANT OF AN INDICATOR

    BY SPECTROPHOTOMETRY

    Re-ee#e%: Ma%es and Prichard= pp. 23@2&.

    Expe!"e#$(* P)e.8e:

    onsult the de%onstrator about the operation of the spectrophoto%eter.

    >ou are pro

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    +iii- he pH %eter should be calibrated using the t$o standard buBer

    solutions pro

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    Expe!"e#$ 15

    DIFFERENTIAL SCANNIN@ CALORIMETRY DSC

    OBECTI&ES

    his e:peri%ent has the follo$ing three obKecti

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    igure 17 iBerential po$er P

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    he soft$are of the S instru%ent gi

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    PROCEDURECefore beginning a fe$ points are $orth noting. Sa%ple $eighings are

    carried out using a %icrogra% balance $ith an uncertainty no greater than afe$ hundredths of a %g@@ta#e the uncertainty to be (.(1( %g. "lso= inrunning soft$are $ith the Per#in@9l%er S& tas#s $ill be acco%plishedthrough using function #eys 1@2.

    ". S Run $ith 4=4@di@n@he:ylo:ya5o:yben5ene1. irst %a#e three +3- $eighings of a pan and a co

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    onditions+other ,nitial 6alue )(.( %D

    3. Place the e%pty sa%ple pan W coOER "" O ,L9S "N G9N9R"9PR,NOES OR 9"H REN.

    C. S run $ith indiu% %etal

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    1. Si%ilarly $eigh a sa%ple= about 1( %g= of ,n %etal in analu%inu% sa%ple pan. "gain place a sa%ple co

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    4. or the liuid crystalline solid deter%ine S +in M *@1 %ol@1- for each

    phase transition. Dhy should there be a large diBerence in S for the

    ) phase transitions7 s n and n iQ

    ;. or the ,n sa%ple= calculate Sfus +in M *@1 %ol@1- for ,n and for each%etal in

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    EPERIMENT 1;

    Ce"!(* O%!**($!)#% (#. W(e%: Te Be*)8%)+>(')$!#%?!!

    Re($!)#

    he study of oscillating che%ical reactions and other syste%s that e:hibit

    e:otic dyna%ics has been a

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    caused by the periodic concentration changes is %ore than co%pensated by

    the entropy increases fro% other processes also conco%itantly proceed in

    the reaction %i:ture. Hence a syste% already at euilibriu% is unli#ely to

    sho$ any oscillatory beha

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    +a- in the redo: potential of the syste%= $hich is controlled by the ratio

    of the concentrations of the reduced to the o:idi5ed for% of the

    %etal ion catalyst V8+nW1-WX?V8nWX=

    +b- the concentrations of the bro%ide ion= VCr@X and

    +c- the colors= based on the concentrations of the colored %etal ion

    co%ple:. or e:a%ple= if ceriu% is used= the color $ill alternate

    bet$een faint bro$n to colorless= and if ferroin is used= the color

    $ill alternate bet$een deep read and blue.

    A%%8"e. Me(#!%" )- $e B> e($!)#.

    he Arst accepted %echanis% $as by Richard ields= 9ndre *oros and

    Richard Noyes at the Eni

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    +3- )e+,6- W H)+OOH-)W CrH+OOH-) x fCr@W other products

    P)e%% A Re($!)#% R1 6 R

    he o

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    VCr@XcriticalZ 1(@;VCrO3@X(

    Dhen VCr@X ` VCr@Xcritical process " do%inates= leading to a decrease in VCr@X.

    Ho$e

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    $hile

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    ,nduction period 1 @@hange@1 ) )w 1hange@) 3 3w )

    etc etc nw n@1