experiment 4 uo

8/18/2019 Experiment 4 UO

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Experiment 4

Abstract

Liquid-liquid extraction is also known as solvent extraction. It is a method of separatingcompound based on their solubility. This experiment was done to separate acetic acid from

its solution in chloroform using water as an extraction solvent. To do this experiment binary

acetic acid-chloroform solution was prepared by adding 4 ml acetic acid to ml chloroform in

a separating funnel. The acetic acid was extracted from the binary mixture using equal mass

of extraction solvent! distilled water which is "# ml. $fter shaking the funnel! it will form two

layers when equilibrium reached. Two empty conical flasks were weighed and each phase

was transferred. The conical flask was then reweighed. Two drops of phenolphthalein was

put into each conical flask and each of them was titrated with %.# & 'a() *aq+ until thecolourless solution turn to pink. $fter calculation! the result obtained is,

Mass of

extract

(g)

Mass of

raffinate

(g)

Mass of Acetic

Acid (A)

In Extract

Phase

(g)

Mass of Acetic

Acid (A)

In Raffinate

Phase

(g)

Theoritical value

(rom Mass !alanceand "raph)

."/ "0.4% %.4"4 "./%0

Actual #alue .""## "4.4## #.0%0 0.%%#

Introduction

Liquid-liquid extraction is also known as solvent extraction. It is a method of separating

compound based on their solubility. It is usually two immiscible solvent. It is an extraction of

a substance from one liquid phase into another liquid phase. Liquid-liquid extraction is a

basic technique in chemical laboratories! where it is performed using a separating funnel.

This type of process is commonly performed after a chemical reaction as part of the work -up.

http://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Laboratoryhttp://en.wikipedia.org/wiki/Laboratoryhttp://en.wikipedia.org/wiki/Separatory_funnelhttp://en.wikipedia.org/wiki/Work-uphttp://en.wikipedia.org/wiki/Work-uphttp://en.wikipedia.org/wiki/Laboratoryhttp://en.wikipedia.org/wiki/Separatory_funnelhttp://en.wikipedia.org/wiki/Work-uphttp://en.wikipedia.org/wiki/Chemistry


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$b%ective

". To separate acetic acid from its solution in chloroform using water as an extraction

solvent.

&hemicals

$cetic acid! chloroform! sodium hydroxide *%.# &+! phenolphthalein indicator.

Apparatus

&easuring cylinder! separating funnel! dropper! hand gloves! retort stand! o-ring! %# ml

volumetric flask! analytical balance and burette.

Procedure

". 1inary acetic acid-chloroform solution was prepared by adding 4 ml acetic acid to a

ml chloroform in a separating funnel. The mixture generated a lot of heat thus

stopper was not put to avoid sudden pressure burst.%. 2hile the mouth of the funnel still open! the mixture was gently swirled to mix it well

into homogenous binary solution. This is the feed solution.0. The acetic acid was extracted from the binary mixture using equal mass of extraction

solvent! water. "# ml of distilled water was measured and poured into the funnel.4. 2ith the use of hand gloves! the stopper was put on and the funnel was shaken

gently. The stopcock was then opened to release the pressure built up. The funnelwas continuosly shaken and vented for about minutes.

. The funnel was put on the o-ring support and the content was let to settle into two

phases. -"# minutes was given to allow the heavy and light phases reach their

equilibrium.3. Two empty conical flask was weighed and each phases was transfered. The conical

flask was then reweighed.. Two drops of phenolphthalein was put into each conical flask and each of them was

titrated with %.# & 'a() *aq+ until the colourless solution turn to pink.

Results and calculation

'ampl Phase eight of empt eight of conical flas* eight of


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econical flas*

(g)

+ solution

(g)

solution

(g)

Rough

extracte

d

(heav)

""#.%33 ""3.4"/% ,-4./0

raffinate

(light)""%.40 "%3.# /4-1,.1

Table /

Table /-/2 Extracted laer

inal reading of burette (ml) 0.#

Initial reading of burette (ml) "."#

Total volume (ml) 3-5

Table /-32 Raffinate(light) laer

inal reading of burette (ml) 00.#

Initial reading of burette (ml) 0.#

Total volume (ml) 3.-5

rom 6nit $peration II Textboo*

E76I8I!RI6M TIE 8I9E' ( I9 EI":T RA&TI$9 )


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&hloroform (!)

Rich 8aer

ater (&)

Rich 8aer

&hloroform

(!)

Acetic Acid

(A)

ater

(&)

&hloroform

(!)

Acetic

Acid

(A)

ater

(&)#.#" #.#### #.## #.##/4 #.#### #."3

#."/ #.#3 #.#"0/ #.#"%" #.%"# #.03

#./### #."% #.#%%/ #.#0# #.44"% #.4//

#.#"0 #.% #.#4"% #.""" #.#"/ #.04"

#.3" #.%3 #.#%# #."/00 #.#3 #.0"""

#. #.0%#/ #.#0 #.%%# #.44" #.%0

#./" #.043" #.#/ #.%// #.4/ #.%0%/

$n the graph for right angle triangular diagram 2

Raffinate ;ome &oordinate

(in 3 decimal place)

Extract ;ome &oordinate

(in 3 decimal place)

x

(!)

<

(A)

x

(A)

<

(A)

#. #.## #.## #.## Tie line pair "

#.% #.# #.#" #.% Tie line pair %

#./# #."/ #.# #.44 Tie line pair 0

#.# #.%3 #." #.# Tie line pair 4

#.3 #.%/ #."/ #." Tie line pair

#.3# #.0% #.% #.4 Tie line pair 3

#.3 #.0 #.% #.4/ Tie line pair

DENSITY = MASS(g)

VOLUME(mL)

MASS ( g )= DENSITY X VOLUME (¿mL)

eed 'olution Extracting 'olvent

&omponentAcetic Acid

(A)

&hloroform

(!)

ater

(&)


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#olume 6sed

(m8)4.## .## "#.##

;ensit ".# ".4/ ".##

Mass (g)

4 ".#

= 4-35

".4/

= >-45

"# ".##

= /5-55

Total Mass (g)

4.% 5 .4

6 //-05

/5-55

&ass fraction of component $ 6

4.20

11.60

6 #.03%"

!asis *no?n2 "".3 g 7eed solution

Total mass balance2

7 5 8 6 &

"".3 5 "#.# 6 %".3

M = 3/-0

A mass balance2

x7 *7+ 5 y8 *8+ 6 x&*&+

#.03%" *"".3+ 5 # 6 x& *%".3+

xM = 5-/.4,

!ased on the graph2


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7rom point E! extract phase contains 5-5., mass fraction of component $ *acetic

acid+

7rom point R! raffinate phase contains 5-3., mass fraction of component $ *acetic

acid+

"".3 g! 7eed *7+

#.03%" $ 9! 9xtract phase

#.# $

&! intermediate

#."4 $

"# g! 9xtract *8+ :! :affinate phase

#.#### $ #.% $

Total mass balance2

7 5 8 6 9 5 :

"".3 5 "#.# 6 9 5 :

%".3 6 9 5 : ................. $

A mass balance2

x () + ' (') = x@(R) + @(E)

#.03%" *"".3+ 5 # 6 #.%: 5 #.#9

4.%##4 6 #.%: 5 #.#9 ................ 1

9 6 %".3 - : ................ ;

'ubstitute & into !2

4.% 6 #.%: 5 #.# *%".3 < :+

4.% 6 #.%: 5 %.#% - #.# :

R = /5->4 g

'ubstitute R = /5->4 g into A2

%".3 6 "#.4 5 9

SINGLE –

STAGE

LIQUID –

LIQUID

EXTRACTION


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E = /5-0 g

• &ass of extract phase, "#./3 g

&ass of acetic acid in extract phase , *#.#+ "#./3 6 ".#0" g

• &ass of raffinate phase, "#.4 g

&ass of acetic acid in raffinate phase, *#.%+ "#.4 6 0."3/0. g

rom the experiment

&olecular formula of acetic acid , ;)0;(()

Element Atomic mass

& "%.#"#

: ".##

$ ".4

Molecular ?eight &:1&$$:%*"%.#"#+ 5 4*".##+ 5 %*".4+

6 05-5,/

or extract phase 2

a b c d

&:1&$$: + 9a$: 9a&:1&$$ + :3$

& , & , 3-5 M

= , = , ( 2.801000 ) L

M a V a

M b V b=1

1

2.0 M of NaOH mol

L X ( 2.801000 ) L X

1mole of CH 3

COOH

1moleof NaOH X 60.0518of CH

3COOH

g

mol

6 #.0030 g of ;)0;(() in extract phase


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or raffinate phase

a b c d

&:1&$$: + 9a$: 9a&:1&$$ + :3$

& , & , 3-5 M

= , = , (29.80

1000 ) L

M a V a

M b V b=1

1

2.0 M of NaOH mol

L X (29.801000 ) L X

1mole of CH 3

COOH

1moleof NaOH X 60.0518of CH

3COOH

g

mol

6 1-,>./ g of &:1&$$: in raffinate phase

Mass of

Extract

(g)

Mass of

Raffinate

(g)

Mass of Acetic

Acid(A)

in extract phase

(g)

Mass of Acetic

Acid (A)

in raffinate

phase

(g)

Theoritical #alue

(from mass balance

and graph)

.4"3 "4.0 ".#0" 0."3/0

Actual #alue "#./3 "#.4 #.0030 0.0


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;iscussion

". $cetic acid is solute $! water is solvent ; and chloroform is diluent 1.%. 9ven though 0 components are added * acetic acid 5 chloroform 5 water + but

there are only % visible phases! which are extract and raffinate.0. 1ecause acetic acid and water reacts with each other! not with chloroform.4. This can be mathematically proved as 4 ml of acetic acid 5 ml of chloroform 5

"# ml of distilled water should produce " ml of solution but the weight to the

conical flask of extract and raffinate content are more than %# ml *%#.0%4 ml+.

. The presence of bubbles in the separating funnel indicated the movement of

water through chloroform! forming intermediate phase momentarily.3. The bubbles produced provide large surface are between the chloroform and

water solvent.. $fter a period of minutes! the intermediate settles to raffinate liquid phase and

extract liquid phase! showing equilibrium.

/. >uring titration of each phase with sodium hydroxide solution *base+! the solution

produced is hot *energy released, exothermic+ due to the breaking of ;-) and ;-

;l bonds found is acetic acid and chloroform solution.

. The end-point of the titration was indicated by the colour change from colourlessto pink by phenolphthalein indicator.

"#. The mass of acetic acid in extract phase in lower than the theoretical value( 5-1>31 B 3-4/>4 ) due to the evaporation of acetic acid into atmosphere.

"". ;ontributing error was from titration error and the presence of random error.

&onclusion

The actual experimented values are ,

&ass of extract phase is >-//55 g

&ass of acetic acid in extract phase is 5-1>31 g

&ass of raffinate phase is /4-4.55 g

&ass of acetic acid in raffinate phase is 1-3.35 g


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Recommendation

". 1e careful not to inhale corrosive acetic acid vapors.%. 1e extra careful not to let your skin comes in contact with chloroform since

chloroform is suspected cancer causing agent.0. =ent the separating funnel frequently during the extraction in order to avoid

the building up of vapour pressure which will blow out the stopcock and

perhaps also the dangerous content.4. ?oint the tip of the separating funnel away from yourself and others.

Reference

" @'IT (?9:$TI(' % , ;&T %#0! >I?L(&$ I' I'>@8T:I$L ;)9&I8T:A% www.wikipedia.org

0 Introduction to (rganic Laboratory Techniques $ 8mall 8cale $pproach. 8econdedition. >onald L.?avia! Bary &. Lampman! Beorge 8.CriD! :andall B.9ngel

experiment 4 uo

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