IB Chem HL Internal Assessment To what extent does the mass of an antacid affect its ability to neutralize the stomach’s pH level? Introduction Acid indigestion, more commonly known by the term “heartburn” is a stomach problem caused by the regurgitation of gastric (stomach) acid. Gastric acid is a fluid found in our digestive system, normally with a pH of around 2.0 (highly acidic on the pH scale), as it is primarily composed of HCl, KCl and NaCl and contributes to the breaking down of all the foods we digest. Heartburn results in a painful burning feeling in the chest and its duration can vary from person to person. Other symptoms include feeling as if there is food stuck in the throat and/or a burning feeling in the pharynx. I chose to examine the pH levels of a few store-bought antacids in relation to a home remedy, in order to determine which of the two types are more effective in the neutralization of gastric acid as it undergoes heartburn, whilst evaluating the mass of each antacid. Antacids usually come in the form of a tablet/pill and are taken to help neutralize stomach acid and reduce symptoms of heartburn, as they are composed of weak bases, such as calcium carbonate or certain hydroxides, for example. Once I was satisfied with my topic, I was able to derive my research question; To what extent does the mass of an antacid affect its ability to neutralize the stomach’s pH level? The neutralization process focuses on the reaction of an acid and a base, resulting in the formation of a salt and water. The reaction would look something like this; HCl + XOH → XCl + H2O When the basic reactant, NaOH, is dissolved in water, it becomes an alkali. The products are a result of the acid and base reacting, forming water as the H+ and OH– react. The second product formed is a salt, NaCl, in this case, as the sodium (Na) and the chlorine (Cl) ions reacted. The independent variable in this investigation is the mass of the antacids, because I can choose the mass of TUMS tablets and baking soda I use in the experiment, whilst the dependent variable is the change in pH levels of the antacids; the number of acid drops required to neutralize the solution. This is measured by counting the amount of acid dropped from the burette. Also, I controlled the temperature to be constant because that might have affected the final rate of reaction and as a result, altered my data. The constant, or controlled variable, was the amount of HCl used. Materials: · Safety goggles · Store-bought antacid (TUMS) · Baking Soda · Mortar & pestle · Hydrochloric acid · Balance · Distilled water · 6 different 100mL beakers · Flask · Universal pH indicators · pH buffer solutions · 50mL graduated cylinder · Burette · pH meter Procedure: 1. Safety goggles were used throughout the entire experiment for safety precautions. 2. TUMS antacid tablet was crushed into a fine powder using the mortar and pestle. 3. The mass of the two antacids were record.

1. IB Chem HL Internal Assessment
To what extent does the mass of an antacid affect its ability
to neutralize the stomach’s pH level?
Introduction
Acid indigestion, more commonly known by the term
“heartburn” is a stomach problem caused by the regurgitation of
gastric (stomach) acid. Gastric acid is a fluid found in our
digestive system, normally with a pH of around 2.0 (highly
acidic on the pH scale), as it is primarily composed of HCl, KCl
and NaCl and contributes to the breaking down of all the foods
we digest. Heartburn results in a painful burning feeling in the
chest and its duration can vary from person to person. Other

2. symptoms include feeling as if there is food stuck in the throat
and/or a burning feeling in the pharynx.
I chose to examine the pH levels of a few store-bought
antacids in relation to a home remedy, in order to determine
which of the two types are more effective in the neutralization
of gastric acid as it undergoes heartburn, whilst evaluating the
mass of each antacid. Antacids usually come in the form of a
tablet/pill and are taken to help neutralize stomach acid and
reduce symptoms of heartburn, as they are composed of weak
bases, such as calcium carbonate or certain hydroxides, for
example.
Once I was satisfied with my topic, I was able to derive my
research question; To what extent does the mass of an antacid
affect its ability to neutralize the stomach’s pH level?
The neutralization process focuses on the reaction of an acid
and a base, resulting in the formation of a salt and water. The
reaction would look something like this;
HCl + XOH → XCl + H2O
When the basic reactant, NaOH, is dissolved in water, it
becomes an alkali. The products are a result of the acid and base
reacting, forming water as the H+ and OH– react. The second
product formed is a salt, NaCl, in this case, as the sodium (Na)
and the chlorine (Cl) ions reacted. The independent variable in
this investigation is the mass of the antacids, because I can
choose the mass of TUMS tablets and baking soda I use in the
experiment, whilst the dependent variable is the change in pH
levels of the antacids; the number of acid drops required to
neutralize the solution. This is measured by counting the
amount of acid dropped from the burette. Also, I controlled the
temperature to be constant because that might have affected the
final rate of reaction and as a result, altered my data. The
constant, or controlled variable, was the amount of HCl used.
Materials:
· Safety goggles
· Store-bought antacid (TUMS)

3. · Baking Soda
· Mortar & pestle
· Hydrochloric acid
· Balance
· Distilled water
· 6 different 100mL beakers
· Flask
· Universal pH indicators
· pH buffer solutions
· 50mL graduated cylinder
· Burette
· pH meter
Procedure:
1. Safety goggles were used throughout the entire experiment
for safety precautions.
2. TUMS antacid tablet was crushed into a fine powder using
the mortar and pestle.
3. The mass of the two antacids were recorded (table 1)
4. Each crushed antacid was placed in its own labelled 100ml
beaker and using the graduated cylinder, 50ml of distilled water
was added to each beaker and the antacids were dissolved.
5. The Universal indicators were added to each beaker and
initial pH of each solution was recorded.
6. Burette was filled with hydrochloric acid solution (HCl) until
it reached the “zero” line.
7. One by one, each labelled beaker was then placed under the
burette and the hydrochloric acid (with pH of approximately
2.0) was added drop by drop into the beaker whilst it was being
swirled until the solution was mixed thoroughly.
8. Numbers of drops were recorded until the solution finally
changed colour (to a pH of approximately 7). Observations were
made.
Before starting the lab, the Tums antacid tablet and the baking
soda were evaluated to see what they were composed of.
Starting with baking soda, its chemical formula is NaHCO3

4. (also called sodium bicarbonate). The Tums antacid is made up
of CaCO3 (calcium carbonate), whereas the Gaviscon tablet is
made of MgCO3, better known as magnesium carbonate. All
three antacids provide fast relief to heartburn symptoms,
however, baking soda contains a high concentration of sodium,
compared to the Tums tablet; therefore it is not commonly used
as a treatment to heartburn relief. Following are the antacids’
balanced chemical reactions;
Baking soda: 2HCl (aq) + 2NaHCO3 (aq) → 2CO2 (g) + 2H2O
(l) + 2NaCl (aq)
Tums: 2HCl (aq) + CaCO3 (aq) → CO2 (g) + H2O (l) + CaCl2
(aq)
Gaviscon: 2HCl (aq) + MgCO3 (aq) → CO2 (g) + H2O (l) +
MgCl2 (aq)
Observations/Qualitative Data
Antacid
Mass of tablet (g)
Drops of HCl until pH was changed to 2.0
Baking soda
1.0g
110 drops
Tums
1.22g
152 drops
Gaviscon
0.76g
87 drops
Table 1: Initial antacid mass and number of drops
Antacid
Initial pH of solution (before HCl)
Final pH of solution (after HCl)
Baking soda
9.2

5. 2.3
Tums
10.6
2.1
Gaviscon
8.1
2.6
Table 2: pH level comparisons (before and after HCl was added)
Antacid
Antacid + universal indicator
Baking soda
Musty, dark green, liquid form
Tums
Blue, liquid form
Gaviscon
Turquoise/aqua blue, liquid form
Table 3: Qualitative data of antacids with indicator added
Calculations and average drops required for each antacid =
drops of acid____
Mass of antacid reacted
Baking soda: 110 ÷ 1.0g = 110 drops/grams
Tums : 152 ÷ 1.22g = 124.6 drops/grams
Gaviscon: 87 ÷ 0.76g = 114.5 drops/grams
***this down below is total bs I have yet to make a GOOD
conclusion..
In conclusion, the bigger the tablet or antacid, the slower its
rate of reaction, because there is less free space for the particles
to move around, which results in an increased digestive time,
causing the heartburn victim to be in pain for a prolonged time
before the antacid kicks in. According to my results, the

6. Gaviscon tablet takes less time to be digested, as its mass is the
smallest (0.76), contrary to the other antacids, ranging from
1.0g to 1.22g.
IB Chemistry—IA Checklist
Design (D)
Aspect 1: Defining the problem and selecting variables
□ Report has a title which clearly reflects what is being done in
this experiment
Research question
□ Research question includes IV and DV
□ A focused problem or a specific research question is
identified and described in enough detail for the reader to
understand the aim of the experiment.
□ A clear hypothesis is stated (not necessary when trying to
measure already known value.)
□ If there is a prediction, it should be quantitative. Make a
sketch graph now; focuses the design later.
Variables
□ The independent variable, dependent variable, and all
variables that are controlled in the experiment are mentioned.

7. □ IV is quantitative
□ DV is quantitative
□ Variables must be described sufficiently to permit replication
(copying) of this experiment.
Aspect 2: Controlling variables
Method for controlling variables
□ The IV is discussed including how it will be manipulated and
the level of the precision (sig figs).
□ The method for the effective control of the variables is
described.
□ Described how the CVs are maintained at constant values; (if
known, identify sig figs).
Materials
□ Indicate all the apparatus and materials used, including the
volumes of tubes and cylinders, the concentrations of solutions,
and the model and manufacturer of any complex apparatus.
Diagramof equipment set-up
□ Annotate this diagram to show how variables were involved –
especially controlled variables. Do not just label the equipment.
Additional diagrams are ok.
Procedure
□ Procedure may be in numbered steps or paragraphs.

8. □ If you use a standard procedure in your method, reference it
using MLA1, APA2, or Council of Biology Editors format3
(note: CBE/CSE format is most
commonly used in science papers).
Aspect 3: Developing a method for data collection
□ Independent variable is tested at minimum 5 increments (or
intervals or “levels”)
□ An adequately broad data range is considered. Data across a
spectrum of independent variable ranges should be considered
when necessary.
□ Minimum 5 trials per IV increment
□ The data gathered enables the aim/ research question/
hypotheses to be adequately addressed.
□ Each piece of data collected is relevant to fulfill the
aim/research question/hypotheses.
□ State how the results will be presented, with reason.
□ Describe any calculations that will need to be completed,
giving formulas where appropriate.
□ Method is described thoroughly and is clearly understandable
to the reader.
□ Procedure addresses safety concerns: appropriate safety
precautions are described.
1 See instructions and examples of MLA format on the web at:

9. http://owl.english.purdue.edu/owl/resource/557/01/
2 See instructions and examples of APA format on the web at:
http://owl.english.purdue.edu/owl/resource/560/01/
3 See instructions and examples of CBE/CSE format on the web
at:
http://writing.wisc.edu/Handbook/DocCBE_NameYear_Intext.ht
ml
Data collection and processing (DCP)
Aspect 1: Recording raw data
There are many fine points to include here – but they are VERY
important to get full marks!
Raw Data
□ Data is collected independently.
□ Data is primarily quantitative (numerical)
□ Data must include qualitative observations. (This may provide
inspiration in the conclusion and especially the evaluation
later.)
□ Raw data recorded in suitable format(s)
Table organization
□ Includes descriptive title (or information can be adequately
stated in table headers; table may have double headers) for any
table, graph, etc. that is used.

10. □ Column & row headers identical to graph axes labels (if table
is source of graph data)
□ IV on left column
□ uses specific terms (ie. NaCl instead of salt; volume instead
of amount; length instead of size)
□ tables not split between pages
□ cells contains only one value
□ tables arranged vertically (usually)
□ tables show grid lines
Table numbers
□ uncertainty in headers after units. Absolute uncertainties
expressed to 1 sig fig.
□ align decimals
□ all values in a column must end at the same decimal place
□ uses significant figures
□ mean contains one more digit than significant figures in
values
□ percentage or relative uncertainties should have 2 sig figs
Table units
□ units in column headings, not in cells
□ units after "/"
□ no parentheses

11. □ use SI units - according to IB
□ Variable that is measured or recorded is clearly stated (e.g. in
the column heading in a table).
□ Units for every variable.
□ Uncertainty of measurements – based on significant digits –in
the column headings.
□ The same level of precision (number of decimal places) is
used for all the items of a variable.
Processed Data
Aspect 2: processing raw data
□ Suitable manner to process the raw data is used (this may
involve a mathematical processing, statistical analysis, or
transforming the data into a suitable graphical representation).
□ All of the raw data has been completely processed.
□ Example calculations provided for substantial processing (ie.
don’t need to demonstrate sum, mean or standard deviation, but
linear regression – if used, for example – should be shown.
□ The raw data has been processed correctly (correctly using
significant figures and uncertainty values).
Aspect 3: presenting processed data
□ Suitable format in which to present the processed data is
used.
□ There are clear headings for all tables

12. □ There are clear titles for all graphs
□ Any graphs have appropriate scales, labelled axes with units
and accurately plotted data points with a suitable best-fit line or
curve if necessary.
□ All the processing stages up to the final result can be
followed easily (explanations are clear where necessary).
□ The final results are shown expressed to the correct number of
significant figures.
□ The uncertainties and errors of raw data have been taken into
account and the work toward this end is shown. (For addition
and subtraction, add absolute uncertainties. For multiplication
and division, add relative or percentage uncertainties.)
Graphing
□ Graph data sourced from single table
□ column & row headings same as graph axes
□ include simple title like "NaCl concentration vs.
transmittance"
□ graph is large (whole page is ideal)
□ simple scale (usually 1,2 or 5 times a multiple/power of 10)
□ [scale does not have to start at zero]
Graphing the X-axis
□ IV
□ Labels
□ Units

13. □ uncertainty (after units, like: mass / g / ± 0.01 )
□ quantitative variable
□ intervals proportional
□ SI units (according to IB)
Graphing the Y-axis
□ DV (even if it is time!)
□ Labels
□ Units
□ uncertainty (after units, like: mass / g / ± 0.01 )
□ quantitative variable
□ intervals proportional
□ SI units (according to IB)
Conclusion & Evaluation (CE)
Aspect 1: Concluding Conclusion
□ Is there a clear pattern in your processed data?
□ A conclusion, which is based on a reasonable interpretation of
the data, is made. Different graphs are compared or trends in
graphs are made explicit. If any hypotheses are being tested, it
is stated whether the data supports these hypotheses.
□ Actual processed data used in conclusion (e.g. quote your
data!)

14. □ A justification is given for my conclusion. Reasons for the
observed trends in data are written explicitly. Experimental
groups are compared with control groups.
□ If an already known and accepted value is being measured,
values have been compared with that in a textbook or other
reference, in order to assess the validity of the result.
Percentage error is mentioned in this case.
□ Any literature/references used is fully referenced using MLA,
APA or Council of Biology Editors format.
Aspect 2: Evaluating procedure
Evaluation
□ The design and method of the investigation have been
evaluated. Including discussion of the replicates and sample
size used. The precision of the study is evaluated.
□ Measurement errors are analyzed to evaluate the accuracy of
measurements.
□ Instrument errors are analyzed (including possibility of
calibration errors - when appropriate) to evaluate the accuracy
of measurements.
□ Random error is evaluated. Random variations in samples that
are uncontrollable should be mentioned.
□ Each error is explained thoroughly and clearly: How might
each have impacted the results?
Aspect 3: Improving the investigation
Improvements

15. □ All improvements are based on the weaknesses and
limitations identified in aspect 2. The specific errors mentioned
are the ones corrected.
□ Modifications to the experimental technique are appropriate
to correct errors mentioned.
□ All proposed modifications are realistic (they are actually
variables that can be controlled).
□ All proposed modifications are clearly explained.
Authenticity and academic integrity
□ All sources of information have been cited in-text
□ All sources have been included in the correct order in the
bibliography
□ Citation is consistent and correct throughout (using MLA,
APA or Council of Biology Editors format.)
□ Student has shown teacher only one draft and has submitted
second draft for assessment
□ Teacher has only assessed final draft
□ Teacher has confirmed that student’s work is their own