Chemistry Full Investigation

TED ANKARA COLLEGE
FOUNDATION HIGH
SCHOOL
CHEMISTRY
ACID - BASE REACTIONS
AMOUNT OF ACETY SALICYCLIC
ACID FOUND IN A TABLET OF
ASPIRIN, CORASPIN & BABY
ASPIRIN
Instructor : Okan Güzel
Student : Umay Atay
FULL INVESTIGATION
ACID – BASE REACTIONS
ACETYL

Umay Atay
1
SALIYCLIC ACID (C9H8O4) (Weak Acid) & NaOH (Strong Base)  TITRATION
ResearchQuestion
What is the amount of acetyl salicylic acid (C9H8O4) in a tablet of
Coraspin, Aspirin and Baby Aspirin through the process of ‘weak acid and
strong base’ titration between the main ingredient of these tablets and a
weak acid Acetyl salicylic acid, dissolved in 30.0 mL ± 0.1 mL water and 20.0
mL ± 0.1 mL Ethyl Alcohol solution, and 0.1 moldm-3 NaOH(aq) as strong base,
by adding 3 drops of Phenolphthalein indicator to the 50.0 mL ± 0.2 mL
solution of ethyl alcohol, water and dissolved ASA, to determine the
equivalence point of the reaction between NaOH and ASA by color change
from colorless to pink, under the same pressure and temperature?
Background Information
Titration 1
Titration is the slow addition of one solution of a known concentration
(called a titrant) to a known volume of another solution of unknown
concentration until the reaction reaches neutralization, which is often indicated
by a color change. The solution called the titrant must satisfy the necessary
requirements to be a primary or secondary standard. In a broad sense, titration
is a technique to determine the concentration of an unknown solution.
Introduction
For acid base titrations, a pH indicator or pH meter is used in order to determine
whether neutralization has been reached and titration is complete. The
information obtained from the process of titration can then be inserted into the
equation, MiVi=MfVf, to determine the concentration of the unknown solution.
Mi and Mf are the initial and final molarities, and Vi and Vf are the initial and final
volumes.
Elements of Titration
• The standard solution is the solution of known concentration. An accurately
measured amount of standard solution is added during titration to the
solution of unkown concentration until the equivalence or endpoint is
reached. The equivalence point is when the reactants are done reacting.
• The solution of unknown concentration is otherwise known as the analyte.
During titration the titrant is added to the analyte in order to achieve the
equivalence point and determine the concentration of the analyte.
• The equivalence point is the ideal point for the completion of titration. In
order to obtain accurate results the equivalence point must be attained
precisely and accurately. The solution of known concentration, or titrant,
must be added to the solution of unknown concentration, or analyte, very
1 http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantitative_Analysis/Titration
Retrieved Date : 01.05.2014

Umay Atay
2
slowly in order to obtain a good result. At the equivalence point the
correct amount of standard solution must be added to fully react with the
unknown concentration.
• The end point of a titration indicates once the equivalence point has
been reached. It is indicated by some form of indicator which varies
depending on what type of titration being done. For example, if a color
indicator is used, the solution will change color when the titration is at
its end point.
To clear confusion, the endpoint and equivalence point are not
necessarily equal, but they do represent the same idea. An endpoint is indicated
by some form of indicator at the end of a titration. An equivalence point is when
the moles of a standard solution (titrant) equal the moles of a solution of
unknown concentration (analyte).
Indicators
The use of an indicator is key in performing a successful titration reaction. The
purpose of the indicator is to show when enough standard solution has been
added to fully react with the unknown concentration. However, an indicator
should only be added when necessary and is dependent upon the solution that is
being titrated. Therefore, indicators must only be added to the solution of
unknown concentration when no visible reaction will occur. Depending on the
solution being titrated, the choice of indicator can become key for the success of
the titration.
2
Acid-Base Titration Reactions
Titration of acid/base reactions involve the process of neutralization in
2 http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantitative_Analysis/Titration
Image 1: This image shows a
titration example with short
descriptions.

Umay Atay
3
order to determine an unknown concentration. Acid-Base titrations can be made
up ofboth strong and weak acids or bases. However, in order to determine the
unknown concentration of an acid or base, you must add the opposite so that
neutralization can be reached. Therefore, an acid of unknown concentration will
be titrated using a basic standard solution and a base of unknown concentration
will be titrated using an acidic standard solution. Examples of acid-
base titrations include include:
• Titration of a Strong Acid with a Strong Base
• Titration of a Weak Acid with a Strong Base
• Titration of a Weak Base with a Strong Acid
• Titration of a Weak Polyprotic Acid
Acid-Base titrations often require the use of some kind of indicator depending on
the strength of acid or base that is being titrated. In some cases a weak base or
weak acid is used or a ph meter which reads the pH of the solution being titrated.
Once the pH of the titrated solution equals seven, either indicated by a change in
color or on a pH meter one can determine that titrations is complete.
Titration of A Weak Acid With A Strong Base
In this reaction a burette is used to administer one solution to another.
The solution administered from the burette is called the titrant. The solution
that the titrant is added to is called the analyte. In a titration of a Weak Acid
with a Strong Base the titrant is a strong base and the analyte is a weak acid.
Aspirin 3
Aspirin (BAN, USAN), also known as acetylsalicylic acid [ASA], is a
salicylate drug, often used as an analgesic to relieve minor aches and pains, as
an antipyretic to reduce fever, and as an anti-inflammatory medication.
Aspirin also has an antiplatelet effect by inhibiting the production of
thromboxane, which under normal circumstances binds platelet molecules
together to create a patch over damaged walls of blood vessels. Because the
platelet patch can become too large and also block blood flow, locally and
downstream, aspirin is also used long-term, at low doses, to help prevent
heart attacks, strokes, and blood clot formation in people at high risk of
developing blood clots. It has also been established that low doses of aspirin
may be given immediately after a heart attack to reduce the risk of another
heart attack or of the death of cardiac tissue. Aspirin may be effective at
preventing certain types of cancer, particularly colorectal cancer.
Chemical properties
Aspirin decomposes rapidly in solutions of ammonium acetate or of
the acetates, carbonates, citrates or hydroxides of the alkali metals. It is stable
in dry air, but gradually hydrolyses in contact with moisture to acetic and
salicylic acids. In solution with alkalis, the hydrolysis proceeds rapidly and
the clear solutions formed may consist entirely of acetate and salicylate.
3 http://en.wikipedia.org/wiki/Aspirin#Chemical_properties

Umay Atay
4
Aim
The aim of this investigation is to determine the mass of acetyl
salicylic acid (C9H8O4) in a Coraspin, Aspirin and Baby Aspirin tablet. The
method of strong base (NaOH) and weak acid (C9H8O4) titration will be used
during the investigation with Phenolphthalein indicator that have
appropriate pH change range (8.2 -10.0) for this experiment.
Phenolphthalein indicator is colorless in acidic solutions and pink in basic
solution so the change of color will be considered to determine equivalence
point of this weak acid – strong base reaction. Then, by considering the
information that the number of moles of acid and base are equal at
equivalence point, the mass of acetyl salicylic acid (C9H8O4) can be calculated.
Variables
Dependent
Volume of NaOH used to reach equivalence point during titration
Independent
The type of the tablet that consists acetyl salicylic acid (C9H8O4)
Controlled Variable
 Molarity of NaOH, 0.1 moldm-3
 Type of the indicator solution used in all trials, phenolphthalein
 Amount of phenolphthalein indicator used in all trials, 3 drops with
pipette
During the titration process, the aqueous solution of weak acids are used to
prevent errors can be sourced by heterogeneous state of the reactant. To have a
homogenous weak acid reactant used the titration, each tablet is dissolved in
constant volume of ethyl alcohol and distilled water before titration, in this
experiment. Ethyl alcohol is preferred for dissolving the tablets faster and more
effective and water is used to prevent impurities. By this way, a homogenous
aqueous ASA is used in weak acid and strong base titration
 Volume of distilled water used in acetyl salicylic acid (C9H8O4)
solution, 30.0 mL ± 0.1
 Volume of ethyl alcohol used in acetyl salicylic acid (C9H8O4) solution,
20.0 mL ± 0.1
 Room Temperature 21.0 ± 0.1°C.
 Temperature of (C9H8O4) Solution, 25.0 ± 0.1°C
 Temperature of NaoH Solution, 20.5 ± 0.1°C
 Room pressure, 1067.0 ± 0.2 hPa.
 Using the same equipments (the same graduated cylinder, erlenmeyer
flask, burette, thermometer etc.) in all trials so that the uncertainties
are kept constant in all trials
Materials

Umay Atay
5
 Coraspin Tablet x3
 Baby Aspirin Tablet x3
 Aspirin Tablet x3
 0.1 M NaOH(aq)
 Mortar & Pestle
 Goggles
 Burette (50.0 mL)
• Stirring Rod
• Phenolphthalein Indicator (27 drops)
• Erlenmeyer Flask (x3)
• Distilled Water, 270.0 mL ± 0.1 mL
• Ethyl Alcohol, 180.0 mL ± 0.1 mL
• Graduated Cylinder (50 mL)
• Thermometer with a range of 0 ℃to 100℃(±0.1 ±℃) x3
• Barometer
• Ring Stand x1
• Data Logger with pH probe
• Weigh Scale
Safety Precautions
• Wear your goggles during the experiment to avoid any possible eye
contact
• Chemical solutions can be irritant and corrosive depending on their
concentrations so avoid skin and eye contact and handle with
appropriate care
Disposal
All solutions in this experiment should be disposed in the proper
waste containers in the fume hood as provided by the instructor in the
laboratory.
Procedure
1. Wear your googles
2. Measure the room temperature with thermometer and pressure with
barometer
3. Find the mass of a Coraspin, Baby Aspirin and Aspirin tablet. Grind
each tablet into a fine powder by using a mortar and pestle.
4. Place each powdered sample into different Erlenmeyer flask
5. Start with the Erlenmeyer flask that contain the solution with a
Coraspin Tablet
6. Add 10.0 ml portion of ethyl alcohol to the flask and stir to dissolve the
powdered tablet in the solution
7. Measure the pH of water by Data logger with pH Probe to keep this
variable constant.
8. Add 25.0 ml water to the flask and stir until the solution looks as a
homogenous solution

Umay Atay
6
9. Measure the temperature of the C9H8O4 (aq) with thermometer
10. Put 3 drops of phenolphthalein indicator in your flask
11. If there’s no 0.1 M NaOH solution in laboratory, take 10 ml 1M NaOH
and add 100 mL distilled water and stir them in a beaker.
12. Measure the temperature of the NaOH(aq)
13. The burette is filled with 0.1 M NaOH. Make sure there are no bubbles
apparent in the burette. Record the initial volume of the burette.
14. Begin titrating, add NaOH in 1.0 ml increments.
15. Stir the flask during titration to understand if the color change is
temporarily or just for instant
16. Close and open the stopcock of the burette until the C9H8O4 (aq)
becomes temporarily pink.
17. Read the lowest point of NaOH(aq) stayed at the eye level on the
burette in order to measure the volume of NaOH(aq) needed to reach
equivalence point (the point through the reaction where the number
of moles of acid is equal to the number of moles of base)
18. Repeat steps 6 -17 for the remaining independent variables, Aspirin
and Alka Seltzer tablets, make at least 3 trials for each different
independent variable
19. Record your data on a table for each trials
20. Pour the solutions in flask and burette into the waste container
Qualitative
Data
• Each tablet grinded in mortar until they
became powdered and emptied carefully into
Image 3: The color change of ASA
solution after titration is shown in this
image. As it seen through the images the
color change from colorless to
temporarily pink is observed during
titration to determine the equivalence
point of the reaction.
Image 2: The ASA solution at the
beginning of titration.

Umay Atay
7
the Erlenmeyer flask after weighing by weighing scale to prevent any
loss from the amount of a tablet.
• Before titration, Acetyl Salicylic Acid (C9H8O4), phenolphthalein and
NaOH solution were colorless.
• The color of solution which contains Ethyl Alcohol, water and acetyl
Salicylic Acid didn’t change immediately when the indicator
phenolphthalein is added.
• Acetyl Salicylic Acid (C9H8O4), phenolphthalein, water and NaOH
solution were odorless but ethyl alcohol had a sharp odor that could
be smelled from 1 m distance from the flask.
• When the burette opened and NaOH solution started to drop into the
flask that contains Acetyl Salicylic Acid Solution and phenolphthalein,
the color of solution started to turn into pink for short time periods
and then it became colorless again.
• As the titration of NaOH continues, the color of pink of the solution in
flask stayed for longer time periods.
Processed Data
1. ConvertingVolumeUnit from mL to L 4
 The unit of Molarity is mol L-1 or mol dm-3 , so we need to convert our
raw data which is recorded as mL to L .
1 L = 1 dm3
1 L = 1000 mL
To convert volume from mL to L
1 L 1000 mL
? n mL
For example,
Trial 1 of Aspirin Titartion
1 L 1000 mL
? 6.5 mL
? = 0.0065 L
4 http://en.wikipedia.org/wiki/Litre
?=
n x 1
1000

Umay Atay
8
Type Of
Tablet
# Of Trials
Volume of
NaOH
Used (L)
±0.0001
Volume of
(C9H8O4)
Solution
(L)
±0.0001
Aspirin
1 0.0065 0.0500
2 0.0060 0.0500
3 0.0070 0.0500
Baby
Aspirin
1 0.0010 0.0500
2 0.0015 0.0500
3 0.0024 0.0500
Coraspin
1 0.0020 0.0500
2 0.0022 0.0500
3 0.0018 0.0500
Table 2: This table shows the converted Volumes of NaOH(aq) and (C9H8O4) in L
with its constant uncertainty value according to the graduated cylinder used
during the experiment.
2. FindingThe Molarity Of Acetyl Salicylic Acid (C9H8O4)
Solution Used
Monoprotic acid is an acid that donates only one proton or hydrogen atom
per molecule to an aqueous solution. Since Acetyl Salicylic Acid is a monoprotic
acid, at the equivalence point, the number of moles of acid is equal to the
number of moles of base. The equivalence point of Acetyl Salicylic Acid and
NaOH reaction, can be determined during titration by using volume of base at
the point the change of color started to stay longer. In this experiment the
color change observed from colorless to pink by phenolphthalein indicator
that added to the solution before the titration. To calculate the number of
moles of acid and base at that point, the molarities should be multiplied by
the volume of acid or base used. So the equation
5Mbase x Vbase = Macid x Vacid
where V is volume of solution in liters and M is molarity in mold dm-3
can be used to calculate the molarity of Acetyl Salicylic Acid (C9H8O4).
Example with the First Trial of Titration Of an Aspirin Tablet
Molarity of NaOH (aq) = 0.1 mold dm-3
Volume Of NaOH(aq) used = 6.5 mL = 0.0065 L
Volume of C9H8O4 (aq) used = 50 mL = 0.05 L
Mbase x Vbase = Macid x Vacid
1. 0.1 x 0.0065 = ? x 0.05
5 Mortimer, Fourth Edition, Chemistry a Conceptual Approach

Umay Atay
9
? = MAcid = 0.013 mol dm-3
Uncertainty Calculation
6Percentage Uncertainty =
 The formula that used to calculate molarity of C9H8O4 (aq) is
Percentage Uncertainty of Volume of C9H8O4 (aq)
Mbase x Vbase = Macid x Vacid
So to calculate the percentage uncertainty of the molarity of C9H8O4 (aq),
thepercentage uncertainty of Mbase , Vbase , Vacid should be calculated
and the sum of these three percentage uncertainty will give us the
percentage uncertainty of Macid .
 The Volume of ethyl alcohol and distilled water are controlled
variables so their percentage uncertainty is constant for all
trials.
Percentage Uncertainty of Volume of C9H8O4 (aq) = Percentage
Uncertainty of Volume of Distilled Water + Percentage Uncertainty of
Volume of Ethyl Alcohol
Percentage Uncertainty of Volume of Distilled Water= (1 x 10-4 / 30 x 10-3 )
= 0.3 %
Percentage Uncertainty of Volume of Ethyl Alcohol = (1 x 10-4 / 20 x 10-3 )
= 0.5 %
Percentage Uncertainty of Volume of C9H8O4 (aq) = 0.3 % + 0.5 % = 0.8 %
 To have 0.1 M NaOH, we take 10 mL ± 0.1 mL 1 M NaoH and
make a solution with 100 mL ± 0.1 mL distilled water and stir them
in a beaker. The uncertainty of 1 M NaOH cannot be calculated
because it was prepared by laboratory technician but the percentage
uncertainty of 0.1M NaOH can be calculated according to the
uncertainty of volume of distilled water and 1 M NaOH.
Themolarity of NaOH is another controlled variable so it will be
constant for all trials.
Percentege Uncertainty of 0.1 M NaOH
= Percentage uncertainty of V1 M NaOH + Percentage uncertainty of
Vdistilled water
= (1 x 10-4 / 10-2 ) x 100 + (1 x 10-4 / 10-1 ) = 1.1 %
For Example Trial 1 of Aspirin
6 http://mauldinchemistry.com/PDF/uncertainty.pdf
Uncertainty
Value
´100

Umay Atay
10
Percentage Uncertainty of Volume of NaOH(aq) = (1 x 10-4 /65 x 10-4 ) x
100
= 1.5 %
Percentage Uncertainty of Molarity of C9H8O4 (aq) = % uncertainty of VNaOH
+ % Uncertainty Of V(ASA) + % uncertainty of MNaOH
= 1.5 % + 0.8 % + 1.1% = 3.4
Type Of Tablet # Of Trials
Molarity of
C9H8O4 (aq)
(mol dm-3 )
Aspirin
1 0.0130 ± 3.4%
2 0.0120 ± 3.6%
3 0.0130 ± 3.3%
Baby Aspirin
1 0.0021 ± 11.9%
2 0.0030 ± 8.6%
3 0.0048 ± 6.0%
Coraspin
1 0.0040 ± 6.9%
2 0.0044 ± 6.4%
3 0.0036 ± 7.4%
Table 3: In the table, the calculated Molarities of C9H8O4 (aq) for each trials are
shown with their percentage uncertainties is shown.
3. Calculating MoleOf Acetyl Salicylic Acid
 The formula of Molarity is 7 where M is molarity, V is volume
of the solution in liter and n is mole , so to find the mole of known
volume and molarity, the M and V should be multiplied.
For Instance, Trial 1 Of Aspirin
Volume of C9H8O4 (aq) = 0.0500
Molarity of C9H8O4 (aq) = 0.0130
M x V = 0.0500 L x 0.0130 mol L-1 = 6.5 x 10-4 mole
Uncertainty of the mole of C9H8O4 (aq)
 The percentage uncertainty of mole is equals to the sum of the percentage
uncertainty of MASA and Volume of C9H8O4 (aq) . The percentage
uncertainties of both have already calculated at previous part of
calculations.
% Uncertainty of Volume of C9H8O4 (aq) = 0.8 %
% Uncertainty of MASA → written on Table 3
7 Mortimer, Fourth Edition, Chemistry a Conceptual Approach
M=
n
V

Umay Atay
11
For Example, Baby Aspirin Trial 1
% Uncertainty of Mole = %
uncertainty of Volume of C9H8O4 (aq) + %
uncertainty of MASA of Baby Aspirin in Trial 1
= 0.8 % + 11.9% = 12.7 %
Type Of Tablet # Of Trials
Mole of C9H8O4
(aq)
(mol)
Aspirin
1 6.5 x 10-4 ± 4.2%
2 6.0 x 10-4 ± 4.4%
3 7.0 x 10-4 ± 4.1%
Baby Aspirin
1 1.0 x 10-4 ± 12.7%
2 1.5 x 10-4 ± 9.4%
3 2.4 x 10-4 ± 6.8%
Coraspin
1 2.0 x 10-4 ± 7.7%
2 2.2 x 10-4 ± 7.2%
3 1.8 x 10-4 ± 8.2%
Table 4: This table shows the Mole number of Mole of C9H8O4 (aq) for each trials with
their percentage uncertainties.
4. Calculating the mass of AcetylSalicylic Acid by The Mole of
C9H8O4 (aq)
 First of all, the mass of a mole C9H8O4 (aq) should be calculated to find
the mass of ASA in tablets.
8Molar mass of ,
Carbon = 12.01 g/mol
Hydrogen= 1.01 g/mol
Oxygen = 16.0 g/mol
C9H8O4 (aq)
9 x 12.01 =108.09
1.01 x 8 = 8.08
Molar mass of C9H8O4 (aq) = 108.9 + 8.08 + 64.0 = 180.17 mol/g
 To calculate the mass of n mole
8 IB Chemistry Data Booklet page 3
16.0 g/mol x 4 =64 g
?=
n x 180.17
1

Umay Atay
12
1 Mole 180.17 g
n mole ? g
For Example, Coraspin Trial 1
Mole of ASA = 2.0 x 10-4
2.0 x 10-4 x 180.17 / 1 = 0.036 g
Uncertainty Of Mass of ASA in a Tablet
 The Uncertainty of the molar mass of C9H8O4 (aq) cannot be calculated
because the values of molar mass of atoms are taken from another
source so the percentage uncertainty of mass is equal to the
percentage uncertainty of mole of C9H8O4 (aq) (given on table 4).
 Calculating Uncertainty value from the percentage Uncertainty
100 n
Mass of C9H8O4 (aq) ?
where n is the percentage value and ? is
uncertainty value of mass.
For Instance, Baby Aspirin Trial 2
% uncertainty of Mole = 9.4 %
Mass of ASA in Trial 2 of Baby Aspirin = 0.027
Uncertainty value of mass = ( 9.4 x 0.027) /100 = 0.0025 ≃ 0.003
Type Of
Tablet
# Of
Trials
Mole of C9H8O4
(aq)
(mol)
Mass of
C9H8O4(aq)
(g)
Aspirin
1 6.5 x 10-4 ± 4.2% 0.117 ±0.005
2 6.0 x 10-4 ± 4.4% 0.108 ±0.005
3 7.0 x 10-4 ± 4.1% 0.126±0.005
Baby
Aspirin
1 1.0 x 10-4 ± 12.7% 0.018 ±0.003
2 1.5 x 10-4 ± 9.4% 0.027 ±0.003
3 2.4 x 10-4 ± 6.8% 0.043 ±0.003
Coraspin
1 2.0 x 10-4 ± 7.7% 0.036 ±0.003
2 2.2 x 10-4 ± 7.2% 0.040 ±0.003
3 1.8 x 10-4 ± 8.2% 0.032 ±0.003
Table 5: In the table the mole of ASA found in each tablet and the mass of ASA
calculated by the mole is shown with uncertainty values of Mass and percentage
uncertainty value of mole of ASA.
5. FindingAverage Massof Acetyl Salicylic Acid (C9H8O4)in Each
?=
n x Mass of ASA
100

Umay Atay
13
Typeof Tablet
9Average Mass in a Tablet =
For Example, Aspirin
= 0.117 g
Uncertainty of Average Mass
= where n is number of trials
For Example, Aspirin
Max. Value of mass= 0.126 g
Min. Value of mass = 0.108 g
Max. Value – Min. Value / = 0.2 → Uncertainty Of Average Mass of
ASA found in Aspirin Tablet
Type Of Tablet Average Mass of ASA (C9H8O4 (aq)) (g)
Aspirin 0.1170 ± 0.2000
Baby Aspirin 0.0296 ± 0.0500
Coraspin 0.0360 ± 0.0600
Table 6 : In his table the average mass of ASA found in each type of tablet according to their 3
trials is shown with their uncertainties.
6. Percentage Difference
10⎜Experimental Value –Literature Value ⎜ x 100
Literature Value
For Instance, Baby Aspirin
Literature Value of Mass of ASA in a Baby Aspirin Tablet = 0.1 g
Experimental Value of Mass of ASA in a Baby Aspirin Tablet = 0.0294 g
⎜0.0294 -0.1⎜ x 100 = 70.6 %
Type Of Tablet Literature Value11 Experimental Value Percentage
9 http://www.basic-mathematics.com/finding-the-average.html
10 http://mauldinchemistry.com/PDF/uncertainty.pdf
Mass of ASA in a tablet of all trialså
Number Of Trials
0.117+0.108+0.126
3
Max. Value - Min. Value
2 n
2 3

Umay Atay
14
(g) (g) Difference (%)
Aspirin 0.5000 0.1170 ± 0.20 76.6
Baby Aspirin 0.1000 0.0296 ± 0.05 70.6
Coraspin 0.1000 0.0360 ± 0.06 64.0
Table 7: This table shows the literature and experimental value of the mass of ASA found in a
tablet in different type of tablets and the percentage difference between them.
CONCLUSION & EVALUATION
Acetyl Salicylic Acid is an acid that often used in medicine and main
ingredient of many painkillers. The aim of this investigation is to determine the
mass of acetyl salicylic acid (C9H8O4 ) in a tablet of Coraspin, Baby Aspirin and
Aspirin, that are easy to access and widely used . I chose ‘weak acid and strong
base titration’ method to reach my aim. At first, the NaOH solution with 0.1 M is
formed by mixing 10.0 mL ± 0.1 mL 1 M NaOH solution and 100.0 mL ± 0.1 mL
distilled water. Then, this 0.1 M NaOH solution is filled in a clean burette. I
measured the weight ach tablet of tablet of Aspirin, Baby Aspirin and Coraspin
that used in trials with weighing scale. Also the pressure of the room and the
temperature of the room, solutions are measured to keep them as controlled
variables. Each tablet are powdered separately by using mortar pestle to make
easy to dissolving of the tablet in 20.0 mL ±0.1 mL ethyl alcohol and 30.0 ± 0.1
mL distilled water solution. Distilled water is chosen to prevent any error that
can source by minerals or chemicals that found in water we use in our daily lives.
Ethyl alcohol is preferred to make the dissolving of the tablet in the solution
easier and faster. Each powdered tablet transferred to a flask that consists mL
distilled water solution from mortar pestle and stirred until the tablet dissolved
completely. Then, 3 drops of phenolphthalein indicator dropped into the flask to
obtain color change during titration and recognize the equivalence point. By
opening and closing the stopcock of the burette, the equivalence point tried to be
reached. When the color became temporarily pink, the stopcock is closed, and
assumed that the reaction has reached the equivalence point. By using data
gained by this experiment, the unknown molarity of C9H8O4 (aq), the mole and
mass of ASA found in a tablet of Aspirin, Coraspin and Baby Aspirin are
calculated and compared with the literature values that are taken from the
prospectus of the tablets. Coraspin and Baby Aspirin had close mass values
during experiment but they were not equal as their literature value shows. The
experimental value of the mass of ASA in an Aspirin tablet is 0.117 g and the
literature value is 0.500 g , the percent difference for Aspirin is 76.6%, for
Coraspin the experimental value of the mass of ASA in a tablet is 0.029 g and the
literature value is 0.100 g so the percent difference is 64.0% and for Baby
aspirin the experimental value of the mass of ASA in a tablet is 0.036 g and the
literature value is 0.100 g, the percent difference equals to 0.6%. High percent
difference is calculated between experimental and literature values, so my
experiment didn’t support the literature value of mass of ASA found in a tablet of
each type of tablet.
This high percent difference at each trail and in conclusion, small gaps
between these percent differences shows us that there is a systematic error in
11 Prospectus of Coraspin, Aspirin & Baby Aspirin

Umay Atay
15
the experiment that can be sourced by equipment, my method, my use of the
method, or my knowledge. The accuracy of the results are low but they have high
precision, that statement is also supports idea of any systematic error.
The molarity of NaOH (0.1 M) was my controlled variable and to prevent any
change during experiment, I prepared this solution in a 100 mL beaker and used
it during the all experiment. Moreover, to keep uncertainties, sourced by
equipment that used during experiment, constant; I used the same equipment
(beaker, thermometer, e.g.) during the experiment. The whole experiment is
done in the same laboratory to keep the physical conditions equal. The
temperature and pressure of the room tried to keep constant by closing the
doors and windows and measuring them before the trials but any other
arrangement weren’t made like using water bath, but the method I used give
efficient and satisfying results to these factors as controlled variables. Opening
and closing the stopcock of the burette is arranged by me so errors may be
occurred sourced by human reflexes and this may cause the deviations to
determine the equivalence point. The time needed to reach the equivalence point
or have color change, temporarily pink, was not measured during the
experiment. Measuring the time needed to reach the equivalence point, the time
intervals between the color change and duration of the color pink appearance
would make data collection more accurate by assuming the duration of
appearance of the color change to the pink as a controlled variable.
To prevent or decrease the errors in the experiment and have closer values
to the literature values, a machine that stir the flask at same speed and with
equal time intervals can be used during titration. By this way, the temporarily
color change would be realized easily and accurately so the equivalence point
would be determined more accurately. Waiting for longer time periods before
each trial for better dissolving of tablet in the solution may decrease the errors.
The experiment can be repeated with water bath to keep temperature as a more
controlled variable and make the system more isolated. Some amount of the
tablet can be lost during powdering and transferring it to the flask so grinding to
powdering can be preferred to decrease the lost or powdering process can be
occurred in a beaker with water and ethyl alcohol to prevent any loss of the
amount of tablet, while powdering the tablets, the tablets will dissolve in water
and ethyl alcohol solution by the same time but glass can break through the
powdering process so high attention is needed for this method. Increasing the
number of trials for each independent variable could help to decrease both
systematic and random errors. By decreasing the volume of water and ethyl
alcohol used to dissolve tablets, the molarity of ASA solution could be increased
and may higher raw data are collected. A color receptor can be used to
determine the color change faster and more accurate during titration can be
used but these kind of equipment are hard to access especially for a high school
laboratory. The values that are measured especially volume are small, using the
equipment that has lower uncertainty values will also decrease the percentage
uncertainty. Moreover, the burette can be cleaned with distilled water or NaOH
for a few more times to decrease impurities in the burette.

Chemistry Full Investigation

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (6)

Similar to Chemistry Full Investigation

Similar to Chemistry Full Investigation (20)

Chemistry Full Investigation