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NAME: CAMROUL HOOKUMCHAND
PRESIDENT’S COLLEGE
CANDIDATE #:
DATE: Skill: P&D
CAP0 CH0&"T3 4#T 1
PRACTICAL # 7
Statement ! "$lem: The Pharmacist at the local drugstore insists on the effectiveness of Brand A antacid over Brand B antacid. antac id. Plan and design an experiment to determine the truth of the pharmacist’s claim. H%"t H%" te'i e'i'': Brand A antacid neutralises more stomach acid than Brand B antacid. Aim: to plan and design an experiment to determine the effectiveness of Brand A antacid and Brand B antacid (aia$le' Dependent/ Dependent/ variables variables 1. Amou Amount nt of of HCl HCl neut neutra rali lize zed d 2. The The pin pin colo colorr chang changee !. The colo colorr change change of pin pin to colo colorle rless ss Independent Independent variable variable 1. Brand B antacid 2. Bran Brand d A anta antaci cid d !. "tan "tanda dard rd #a$H #a$H Controlled variable 1. %olume lume of HCl HCl adde added d 2. &ass &ass of of 'oth 'oth ant antaci acid d (eighe (eighed d !. %olume lume of of stan standar dard d #a$H #a$H Rea) Rea)en ent' t' 1. Bran Brand d A anta antaci cid d 2. Brand B antacid !. 2)) cm! HCl acid * ).1 mol+dm!, -. Phenolp Phenolphth hthale alein in indica indicator tor *1, *1, /. "tanda "tandard rd #a$H #a$H solu solutio tion n * ).1 ).1 mol+d mol+dm m!,
Mateial'
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1)) cm! Conical flas 2/ cm! Burette 1)) cm! measuring c5linder 0lectric scale Calculator 6a' coat 7oggles 7loves etort stand "tirring rod
P*e+,e: P*e+, e: -a*k titatin tita tin met+
1. 8irstl5 8irstl5 gather the the materials materials (ith (ith the reagents reagents re9uire re9uire for the experiment experiment:: at that time crushed 2/ grams of Brand A antacid and 2/ grams of Brand B antacid. 2.
8ormerl5 8ormerl5 dissolve dissolve 'oth 'oth samples samples of antacid antacid in separate separate conical conical flas flas (ith (ith 2/ cm! HCl each and add one drop of Phenolphthalein indicator.
!.
6ater 6ater fill fill the 'urett 'urettee to to the the zero zero mar mar (ith (ith #a$H: then used that 'urette to titrate over the HCl until a pin coloration is seen *endpoint,.
-.
epeat the the procedure procedure (ith (ith the other conical flas flas containi containing ng the other other antacid antacid and precisel5 record the amounts of HCl added and then mae necessar5 calculation.
/. 8inall5 8inall5 recap procedur proceduree 1: 2: ! and - to gain gain maximum accurac5 accurac5 (ith (ith the result results: s: the effectiveness of the antacid (that is the amount of HCl neutralised by antacid) can 'e calculated '5 the amount of #a$H added into the HCl solution to neutralise it.
Dia)am' . *min) 'n / ,n+e *n't,*tin'0
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Re',lt Re' ,lt'': The below table shows the amount of NaOH that was required to neutralise HCl (containing antacid
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Tial
%olume+cm!
Titatin
nitial
(l,me ! NaOH A5
(l,me ! NaOH A6
8inal
-5
-6
Titre
A5-51 85
A6-6 1 86
Teatment Teatme nt ! +ata +a ta / *al*,l *al *,lati atin' n' 0
The effectiveness of the various antacid could 'e calculated '5;
2/cm! #a$H is added to the 'urette and !" cm! is used to neutralise the
Case 2 neutralise the HCl solution.
2/cm! #a$H is added to the 'urette and #$%" cm! is used to
•
Therefore the antacid in case 2 is more effective since less #a$H (as re9uired to neutralise the HCl solution. This sho(ed that in case more HCl (as neutralised '5 the antacid used: thus re9uiring less amount of #a$H to 'ring it to a pH around >.
Also considering the e9uation 'elo(; #a$H *a9, ? HC6 *a9, #aCl*s, ? H2$ *6, 1;1 ratio "ince the ratio is one to one on e the amount of HCl neutralised can 'e calculated easil5 '5; NO ! Mle 1 M 2 3l,me *this is sho(n in the ta'le on the next page,
Te ta$le $el4 '4' te $eak +4n *al*,latin' ! te n,m$e ! mle' ! te t4 anta*i+ ,'e+
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Antacid B #$ of &ole = & x volume = 3 mol+dm! x !@ dm! 1 98 mle' HCl ne,tali'e+
"teps #$
#$ of &ole = & x volume = 3 mol+dm! x 2@ dm! 1 68 mle' HCl ne,tali'e+
Then this antacid is stronger since onl5 68 mle' HCl (as neutralised '5 #a$H to 'ring it to endpoint. This sho(ed that the antacid has done some extra (or in comparison to Antacid B
This antacid is (eaer since 98 mle' HCl (as neutralised '5 #a$H to 'ring it to endpoint. This sho(ed that the antacid has done less (or in comparison to Antacid A
Therefore amount of HCl neutralised b& antacid are'
Antacid A
!$
3 mol+dm! x >@ dm!* total HCl added, mole present 'efore 1 78 mle' titration
Ther Theref efor oree amo amoun untt of HC HCll neut neutra rali lise sed d b& b& antacid are'
3 mol+dm! x >@ dm!* total HCl added, mole present 'efore 1 78 mle' titration
oles neutralised neutralised b& b& antacid >@3 moles !@3 moles = -@3 &oles
)$
oles neutralised neutralised b& b& antacid >@3 moles 2@3 moles = /@3 &oles
f active ingredient is &g*$H,2 Consider the e9uation; M)/OH06 ; 6HCl M)Cl6 ; 6H6O
+$
f active ingredient is &g*$H,2 Consider the e9uation; M)/OH06 ; 6HCl M)Cl6 ; 6H6O
Since the Ratio is 1:2, then !"* moles of antacid is used here h ere
Since the Ratio is 1:2, then !$% "* moles of antacid is used here
#ote; the active ingredient ingredient M)/OH0 6 is used as an example: this mean that the ratio can changed 'ased on (hich active ingredient is used
#ote; the active ingredient ingredient M)/OH0 6 is used as an example: this mean that the ratio can changed 'ased on (hich active ingredient is used
A'',m"tin': The antacid A is more effective if less #a$H is needed to neutralize the HCl: that is: more HCl (as alread5 neutralize '5 the antacid. an tacid. Also Also if more moles of antacid is used up (ith the same
9/12 B. Roopnarain
amount of HCl then that HCl acid is more stronger+effective. This can 'e seen from the example (here M) /OH06 is used to demonstrate.
P''i$le S,*e' ! e' an+ limitatin' 5< The titration must 'e stop (hen the pin coloration is seen 6< A (hite paper sheet of paper must 'e place under the conical flas to o'serve the pin p in colour 'etter. 9< T(o T(o more accurate titrations must 'e performed to gain g ain maximum accurac5. =< All utensils should 'e (ashed and dr5 (hen repeating titrations. >< The electric scale should 'e zeroed 'efore measuring the mass of antacid. ?< The antacid purchased must not 'e ' e closed or on+after to its expir5 date.
Cn*l, Cn *l,'i 'in n f the determining factor: that is: the num'er of moles of HCl neutralised '5 #a$H is less (hen the Brand A antacid is used rather than (hen Brand B antacid is used then the h5pothesis is supported if not then the h5pothesis h 5pothesis is not supported.
