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CHM 421 ANALYTICAL CHEMISTRY
CHM 421 Analytical Chemistry
EXPERIMENT 3 TITLE: Neutralization Capacity Of Commercial Antacid Tablet Tablet NAME:
MUHAMMAD AMIRUL AKMAL BIN MOHD HASAN
STUDENT ID:
2014217884
GROUP :
ED2605A
PROGRAMME :
EDUCATION
DATE DATE OF OF EXPERIMENT :
18102016
DATE REPORT SUBMITTED :
25102016
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CHM 421 ANALYTICAL CHEMISTRY
LECTURER :
MADAM SUHAILA BINTI HANAPI
EXPERIMENT 3: Neutralization Capacity Of Commercial Antacid Tablet
A!TRACT:
In this experiment, there are three main objectives that need to be achieved. Firstly is to prepare 250ml of 0.5M hydrochloric acid solution from 6.M !l. "he volume of acid re#uired is calculated by usin$ formula, M!%! & M'%' (here the aftermath of calculation, volume of !l re#uired is 20.)ml. Mean(hile, volume of distilled (ater that needs to be used in this preparation is also calculated as it should be )0* of calculated volume of distilled (ater and is said to be +).-ml of distilled (ater. In a 250ml of conical flas, these t(o solutions are mixed up (ell and labeled as prepared hydrochloric acid solution that needs to be used throu$hout this experiment. "he second objective that needs to be achieved is to standardi/e the acid a$ainst sodium hydroxide. "he standard sodium hydroxide solution has been prepared earlier durin$ previous experiment 2 (here the molarity of sodium hydroxide solution is said to be 0.+-M. "he prepared hydrochloric acid solution is titrated (ith the standard sodium hydroxide solution and thus to standardi/e the acid solution to $et the molarity of !l (hich is on avera$e of 0.2M. "he last objective for this experiment that needs to fulfill is to determine the neutrali/ation capacity of a commercial antacid tablet. "he active in$redients found in the antacid tablet is aluminium hydroxide, 1l 34. "he purpose of this experiment (as to determine the molarity of a solution and the percent by mass of acetic acid, !!33, in a commercial vine$ar sample by titration (ith a standardi/ed sodium hydroxide solution. "he percenta$e of !!33 (as found to be .0+*. "he exact value (as -.00* from the label on the commercial vine$ar sample.
O"ECTI#E!:
+. "o prepare hydrochloric acid solution. 2. "o standardi/e the acid a$ainst sodium hydroxide. 2
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CHM 421 ANALYTICAL CHEMISTRY
. "o determine neutrali/ation capacity of a commercial antacid tablet.
INTRO$%CTION:
"he stomachs acidic interior is $enerated by stomach acid essentially 0.+ M hydrochloric acid4. "his acid is necessary for di$estion but too much stomach acid can cause discomfort. 3ne (ay of relievin$ excess acidity in the stomach is to neutrali/e some of the acid (ith a (ea base or antacid. Most antacids contain some ind of carbonate for example, 7a!3 or !a!34 that react (ith stron$ acid to mae carbonic acid, 2!3, (hich then dissociates to (ater and carbon dioxide $as8
2!3 a#4
23 l4 9 !32 $4
Many commercial preparations are available in tablet form. "hese tablets $enerally contain binders and flavorin$s a$ents in addition to the (ea base, so (e cannot just assume that a bi$$er tablet is more effective. Instead, (e can determine the exact number of moles of base in a tablet by reactin$ it (ith acid: this (ill be the tablets acid neutrali/in$ capacity 17!4. Instead of titratin$ the antacid directly (ith an acid, you (ill employ bac;titration8 addin$ a no(n excess of acid to the tablets and then titratin$ the excess acid carefully (ith a standard solution of stron$ base. "here are t(o $ood reasons for this procedure8 +4 most antacid tablets dissolve very slo(ly in (ater but much faster in acids since they react as they dissolve4, and 24 carbon dioxide from the air and from the breath dissolves in (ater and acts as an acid
!
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CHM 421 ANALYTICAL CHEMISTRY
reactin$ immediately to neutrali/e any basic solution ; thus it is best to avoid leavin$ basic solutions standin$ in the air for lon$ periods of time4.
MET&O$!: A' Preparation of t(e (ydroc(loric acid'
%olume of 6.0M !l that need to prepare 250ml of 0.5M !l and volume of distilled (ater re#uired (ere calculated.
1bout )0* of the re#uired distilled (ater (as poured into a 250ml conical flas. "he calculated volume of 6.0M !l (as measured and transferred to the conical flas. "hen, distilled (ater (as added to mae up to 250ml mar on the conical flas.
"he flas (as carefully covered (ith parafilm and the solution (as mixed (ell. "hen solution (as labelled.
' !tandardization of t(e acid a)ain*t *odium (ydro+ide'
1 50ml burette (as rinsed and filled (ith standard 7a3 solution. "he initial readin$ (as recorded.
+0.0 ml of prepared hydrochloric acid solution (as accurately pipetted and transferred into conical flas. 20ml distilled (ater and drops pf phenolphthalein (as added to the flas and (as titrated to the end;point (ith standard 7a3 solution.
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"he final readin$ of titrant (as recorded and this titration (as repeated t(o times more.
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CHM 421 ANALYTICAL CHEMISTRY
C' $etermination of neutralization capacity of an antacid tablet'
"he burette used at procedure <4 (as refilled (ith 7a3 solution. "he initial readin$ (as recorded.
3ne antacid tablet (as obtained and the mass (as (ei$hed (ithout touchin$ it. "he mass of tablet (as recorded.
"he antacid tablet (as carefully crashed usin$ a mortar and pestle. "he crush tablet (as split into t(o or three samples of about similar (ei$hts. =ach sample (as re(ei$hed and the mass (as recorded. "hen each sample (as transferred to a 250ml conical flas.
25ml of distilled (ater (as measured and poured to flas. 25.0ml of standard acid (as dispensed usin$ a volumetric pipette into the flas contained the crashed tablet.
"he content in the flas (as heated on a hot plate and (as boiled $ently for 5 minutes. "he solution in the flas (as contained the remainin$ acid solution and (as checed usin$ litmus paper.
"he solution (as let to cool do(n to room temperature by placin$ the flas in a beaer of tap (ater. "hen 5 drops of pheno lphthalein indicator (ere added to the solution. "he titration (as repeated (ith other t(o samples and the data (as recorded.
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CHM 421 ANALYTICAL CHEMISTRY
RE!%,T!: EXPERIMENT 3 : NE%TRA,I!ATION CAPACIT- O. COMMERCIA, ANTACI$ TA,ET A' PREPARATION O. &-$ROC&,ORIC ACI$ !O,%TION %olume of 6.0 M !> taen & ' !tandardi*ation of t(e acid a)ain*t !odium &ydro+ide
%olume of the acid used m>4 Final readin$ of 7a3 Initial readin$ of 7a3 %olume of 7a3 m>4 used
?ou$h +0.0 2-.2 50.0 25.)
+ +0.0 26.0 50.0 2-.0
2 +0.0 25.0 50.0 25.0
C' $etermination of Neutrali*ation Capacity of an Antacid Tablet'
@ei$ht of one (hole antacid tablet &
@ei$ht of crushed antacid tablet %olume of standard !> added m>4 Final readin$ of standard 7a3 Initial readin$ of standard 7a3 %olume of standard 7a3 m>4 used
/ 0.000 25
0 0.2655 25
50.0 52.6
50.0 52.6
CALCULATION: A. PREPARATION OF HYDROCHLORIC SOLUTION
McVc = MDVD
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CHM 421 ANALYTICAL CHEMISTRY
(0.5 M )( 250 mL )
M 2 V 2
Vc =
Mc
=
6.0 M
= 20.8 mL
250 mL – 20.8 mL = 229.2 mL H 2O 80 100
x 229.2
=183.4 mL H 2 O
B. STANDARDISATION OF THE ACID AGAINST SODIUM HYDROXIDE
Atandard 7a3 from experiment 2
+0.0 m> !l 9 20.0 m> 'istilled @ater 9 drops of phenolphthalein
The chemical equation:
HCl (aq ! "aOH (aq # "aCl (aq ! H2O (l
M$V$ = M %V % M B = Molarity of NaOH from experiment 2 = 0.1827 M V A = 10.0 mL M A =? V B = Volume of NaOH ue! from titration. I.
ROUGH
Calculatin& Mola'it o) HCl* M % = (0.+82, M - 25.8 mL +0.0 mL = 0./,+/ M II.
TITRATION 1
Calculatin& Mola'it o) HCl* M % = (0.+82, M - 2/.0 mL +0.0 mL = 0./85 M
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CHM 421 ANALYTICAL CHEMISTRY
III. TITRATION 2
Calculatin& Mola'it o) HCl* M % = (0.+82, M - 25.0 mL +0.0 mL = 0./518 M
%e'a&e Mola'it = (0./,+/ ! 0./85 ! 0./518 = 0./551 M
C. DETERMINATION OF NEUTRALISATION CAPACITY OF AN ANTACID TABLET Chemica E!"a#i$%:
C"CO! #$% & H& #"'% B# C"2& #"'% & HCO!( #"'% HCO!( #"'% & H& #"'% B# H2CO! #"'% B# CO2 #)% & H2O #* M %V %=M$V$ M B = Molarity of tan!ar! olution NaOH = 0.1827 M V B = Volume of NaOH ue! V % = Volume o) 3tan4a'4 HCl a44e4 = 25 mL M % = I.
TITRATION 1
Calculatin& o) Mola'it antaci4 HCl = (0.+82, M - 52.1 mL 25.0 mL = 0./// M II.
TITRATION 2
Calculatin& o) Mola'it antaci4 HCl = (0.+82, M - 5.0 mL 25.0 mL = 0.8, M
%e'a&e Mola'it = (0./// ! 0.8, 2 = 0.159 M
Readin) /
7o of mole & 0.---M425m>4C+000 ; 0.+-M452.6m>4C+000 & +.2-6 8
×
+0; mol
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CHM 421 ANALYTICAL CHEMISTRY
7a3 9 !l # "aCl ! H2O HCl ! %l(OH # %lCl ! H2O
+ mol of 1l34 & +.2-6
Mass of 1l34 & -.+5
×
×
+0; mol C & -.+5
+0;- mol
×
×
+0;- mol
D).006$Cmol & 0.02- $
Eercenta$e of hydroxide per $ of antacid sample & 0.02- $ C 0.000
×
+00 & +0.)0 *
7eutrali/ation capacity of antacid per $ram & moles !l neutrali/e C mass of antacid & D.
×
+0; molC 0.00 $ & 0.02--
Readin) 0
7o of mole & 0.8, M425m>4C+000 ; 0.+-M452.6m>4C+000 & 2.+)5 7a3 9 !l # "aCl ! H2O HCl ! %l(OH # %lCl ! H2O
+ mol of 1l34 & 2.+)5
Mass of 1l34 & D.D2)
×
×
+0; mol C & D.D2)
+0;- mol
×
+
×
+00 & 22.D0 *
+0;- mol
D).006$Cmol & 0.0602) $
Eercenta$e of hydroxide per $ of antacid sample & 0.0602) $ $ C 0.2655
×
×
+0; mol
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CHM 421 ANALYTICAL CHEMISTRY
7eutrali/ation capacity of antacid per $ram & moles !l neutrali/e C mass of antacid & D.
×
+0; molC 0.2655 $ & 0.02D6
7eutrali/ation capacity of one (hole antacid tablet & 0.02--C0.02D6 &0.))-+
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CHM 421 ANALYTICAL CHEMISTRY
$I!C%!!ION: The )i'3t 6a't o) thi3 e-6e'iment i3 a7out a 6'e6a'ation o) the h4'ochlo'ic aci4 3olution* he'e e nee4 to calculate the olume o) 1.0M HCl an4 6'e6a'e a7out 250 mL o) 0.5M HCl. The olume o) 1.0 M HCl i3 taen a7out 20.8 mL* he'e the olume i3 taen )'om 6'e6a'ation o) 250 mL o) 0.5 M HCl. Then the olume taen i3 mi-e4 ith 4i3tille4 ate' in the conical )la3. n othe' to 4ete'mine the olume o) H2O* e nee4 to minu3 the olume o) 3olution hich i3 250 mL ith olume o) HCl. The'e)o'e* e can 4ete'mine the olume o) 4i3tille4 ate' o' H 20 )'om the olume o) HCl that e &et 7 time3 it ith 80; o) olume H 2O. The 3econ4 6a't o) thi3 e-6e'iment i3 a7out to 3tan4a'4i
'om the 'e3ult o7taine4* e can )in4 the mola'it o) HCl 7 u3e4 a )o'mula M $V$= M %V %? he'e M$ = Mola'it o) 3tan4a'4 "aOH? V $ = Volume o) "aOH u3e4 in a tit'ation? V % = Volume o) %ci4 u3e4. Thu3* the ae'a&e mola'it o) HCl i3 0./511 M. The la3t 6a't o) thi3 e-6e'iment i3 to 4ete'mine the neut'ali
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CHM 421 ANALYTICAL CHEMISTRY e-ce33 aci4. Then* )'om thi3* e can calculate ho much aci4 'eacte4 ith the antaci4. Thi3 aci4 ill 'eact ith the "aOH e a'e tit'atin& an4 &ie u3 inaccu'ate 'e3ult3. The'e)o'e* it i3 im6o'tant to 7oil the 3olution hen the ca'7onate 'eact3 ith aci4* to 'emoe CO
2
a3 a &a3.
Volume o) HCl a44e4 i3 25.0 mL a3 an analte. >'om the tit'ation 'e3ult* then e o7taine4 the olume o) "aOH u3e4 i3 52.1 mL )o' )i'3t an4 3econ4 tit'ation. Then )'om the 'e3ult o7taine4 e 4ete'mine the ma33 an4 the 6e'centa&e o) h4'o-i4e ion i3 +1.//;.
Aeveral precautionary steps need to be taen. Firstly, mae sure all the apparatus that $oin$ to be used are clean as possible to avoid any contamination occurs. Aecondly, the proper handlin$ and the correct techni#ue to measure correct volume of reactant and time should $ive more attention to reduce results error. >astly, mae sure to dispose any (aste chemicals in the assi$ned disposable area. In order to have more accurate, the experiment must be repeated at least three time and the accuracy must be improved.
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CHM 421 ANALYTICAL CHEMISTRY
CONC,%!ION:
From the experiment, it is no(n that the avera$e molarity of !l durin$ standardi/ation a$ainst sodium hydroxide solution is 0.2M (hile the capacity of neutrali/ation of one (hole antacid tablet is said to be 0.))-+.
1%E!TION!:
+. 1cid is al(ays added to (ater, and never reverse. @hy. 1 lar$e amount of heat is released (hen stron$ acids are mixed (ith (ater. If (ater (as added to acid, it form an extremely concentrated solution of acid initially. Ao much heat is released that the solution may boil very violently, splashin$ concentrated acid out of the container. If acid (as added to (ater, the solution that forms is very dilute and the small amount of heat released is not enou$h to vapori/e and spatter it. 2. @rite a balanced chemical e#uation for the reaction of the antacid (ith !l if the antacid contains hydroxide ion. !la#4remainin$ 9 7a3a#4 & 7a!la#4 9 23l4
. @rite a balanced chemical e#uation for the reaction if the antacid contains carbonate ion. !3 2;a#4 9 23 l 4 !3 ;a#4 9 3;a#4
RE.ERENCE!:
1!
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CHM 421 ANALYTICAL CHEMISTRY
Guraidah 1bdullah Munir, G. . 20+54. Analytical Chemistry Lab Manual. Huala >umpur8 Eenerbit Eress niversiti "enolo$i Mara.
Determination of the Amount of Acid Neutralized by an Antacid Tablet Using Back Titration. n.d.4.
?etrieved
3ctober
22,
20+6,
from
(ebassi$n.net8
http8CC(((.(ebassi$n.netClabs$raceperiodCucsc$encheml+ClabJ-Cmanual.pdf
Chan&* B. (200,. Chemi3t'* 9th e4ition4. McE'a@Hill. +50 @ ,09
'avid 7.
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