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Carmel Holy Word Secondary School (AL Chemistry)

Form 6 Chemistry Practical

Experiment 17 !istri"#tion o$ a sol#te "et%een t%o immisci"le sol&ents

Introduction

'n many reactions imp#re prod#ct is o"tained For example the reaction may ha&e "een

carried o#t in a*#eo#s sol#tion and at the end o$ the reaction there may "e present #nreacted

startin+ materials and #n%anted side,prod#cts A techni*#e -no%n as sol&ent extraction may "e

#sed to o"tain the p#re prod#ct .he a*#eo#s sol#tion is sha-en %ith another sol&ent that does not

mixed %ith %ater S#ch sol&ents are said to "e immisci"le %ith %ater co#ld "e $or example ether

CCl / .he immisci"le sol&ent is chosen s#ch that the s#"stance that are %anted %ill dissol&e in it

lea&in+ the other s#"stance in the %ater layer .he sol&ent are separated and i$ necessary the

proced#re is repeated "y addin+ more o$ the or+anic sol&ent to the a*#eo#s layer sha-in+ thesol#tions to+ether separatin+ them and r#nnin+ o$ the sol#tion containin+ the re*#ired prod#ct

.he sol#tion o$$ the prod#ct are p#t to+ether and sha-en %ith a s#ita"le solid dryin+ a+ent to

remo&e the small amo#nt o$ %ater carried o&er Finally the or+anic sol#te can "e separated $rom

the sol&ent "y distillation or "y crystalli0ation

'n the $ollo%in+ experiment it is ass#med that yo# -no% that a certain mass o$ a sol#te %ill

dissol&e in a +i&en mass o$ sol&ent at a partic#lar temperat#re #t %hat happens %hen the same

mass o$ sol#te is dissol&ed "et%een t%o immisci"le sol&ents in the same $las-2

.his experiment is concerned %ith the distri"#tion o$ ethanoic acid "et%een t%o sol&ents that

may "e considered to "e immisci"le "#tan,1,ol and %ater Sol#tions o$ the acid in the t%o sol&ents

are sha-en to+ether allo%ed to separate and analy0ed "y titratin+ a sample o$ each layer %ith

sodi#m hydroxide sol#tion

.he proced#re is repeated se&eral times #sin+ di$$erent concentration o$ acid and yo# %ill

then "e a"le to see %hether there is any simple relationship "et%een the concentrations o$ the acid

in each sol&ent

Apparatus

3 meas#rin+ cylinder $or meas#rin+ %ater "#tan,1,ol and ethanoic sol#tion to "e shared "y

st#dents on each "ench

pipette $illers pipette (14ml)

separatin+ $#nnel (5 4ml)

titration $las-s (5 4ml)

meas#rin+ cylinder (14 5 ml)Reagents

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8/12/2019 exp17

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Carmel Holy Word Secondary School (AL Chemistry)

#tan,1,ol 144ml per +ro#p

58 ethanoic acid 154ml

4 8 9a:H a"o#t 1 4ml

phenolphthalein indicator

Procedures

1 From the meas#rin+ cylinder add 5 cm 3 o$ "#tan,1,ol 14cm 3 58 ethanoic acid and /4

cm 3 %ater into the separatin+ $#nnel

5 Sha-e the mixt#re $or a"o#t min#tes to allo% ethanoic acid to dissol&e in "oth layer

;eep yo#r hand on the stopper and hold the tap %ith the other hand Al%ays -eep the epeat the experiments a"o&e %ith three other mixt#res o$ "#tan,1,ol %ater and ethanoic

acid o#tline in the ta"le

>ecord yo#r res#lts into the ta"le "elo%

9 !: 9:. P:=> :>?A9'C S:L@E9.S !:W9 .HE S'9; P:=> .HE8

'9.: .HE WAS.E S:L@E9. :..LE P>:@'!E!

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Carmel Holy Word Secondary School (AL Chemistry)

Result

8ixt#re #tan,1,ol cm 3 Ethanoic acid cm 3 Water cm 3 .itre cm 3

:r+anic layer A*#eo#s layer 1 5 14 /45 5 5 5

3 5 3 1/ 5 4 4

Data Treatment

1 Constr#ct a +raph "y plottin+ the &ol#me o$ sodi#m hydroxide #sed to titrate the acid in the

"#tan,1,ol layer a+ainst the &ol#me #sed to titrate the acid in the %ater layer

5 What is the *#antitati&e si+ni$icance o$ the slope o$ the +raph yo# ha&e o"tained2

3 Why m#st the immisci"le sol#tion "e separated "e$ore the ethanoic acid is titrated2

/ 4 5+ o$ a s#"stance are dissol&ed in 144cm 3 o$ a sol&ent As m#ch o$ as possi"le is to "e

extracted $rom sol&ent to a second sol&ent A %hich is immisci"le %ith .he partition

coe$$icient "et%een the t%o sol&ents is / at the temperat#re o$ the operation

Calc#late %hether it is more e$$ecti&e to sha-e the sol#tion o$ in %ith 144cm 3 o$ A or %ith

t%o separate portions o$ 4cm 3 o$ A

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