Chinese General Hospital Colleges
College of Nursing
S.Y. 2024-2025
EXPERIMENT 2: SOLUTIONS AND BUFFERS
Submitted by:
MATEO, SOPHIA NICOLE
OBIASCA, CLARREN EMANUEL
PABLO, HANZELLE KIM
PEREZ, KEN ANDREI
RAMOS, CHYNNA JULIA
RIO, RICA
BSN-1A
Introduction of Concepts and Significance
Buffers play a crucial role in maintaining pH balance in biological and chemical systems.
A buffer solution is a water-based mixture containing either a weak acid and its conjugate base
or a weak base and its conjugate acid. Buffers neutralize added acids or bases to maintain
stability. ( BJYUS Admin, 2023) stated that a Buffer solution has a definite pH and does not
change in dilution. As Mutedzi (2019) explains, this resistance to pH changes is vital in many
solutions to resist significant pH changes upon dilution or the addition of small amounts of acids
or bases. Consequently, this property is essential for various applications, including fermentation,
food preservation, drug delivery, and enzyme activity. According to (Libretexts, 2022a) Without
buffers, even minor pH fluctuations could lead to enzyme denaturation, disrupted metabolic
pathways, or cellular damage.
Moreover, as explained by Petri & Land (2017), buffers work by neutralizing small
amounts of added acids or bases, thereby stabilizing the pH. This stability is vital in biological
systems where processes such as enzyme function and cellular health depend on maintaining a
specific pH range. In fact, Chandra Mohan, Ph.D. (2006), highlights that buffers help keep the
pH of intracellular and extracellular fluids within a narrow range despite internal and external
influences.
Understanding how buffers work is important in both science and everyday life. In
biology, many processes like enzyme activity and cell function depend on having a stable pH.
Buffers help maintain this stability, which is essential for these processes to work properly. In
this experiment, we observe how a phosphate buffer handles acids and bases, showing how
buffers are used in labs and biological systems to keep pH levels stable, ensuring accuracy and
proper function.
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Flowchart of Procedure
Figure 1: Flowchart of Procedure for Calibration of the pH meter
Figure 2: Flowchart of Procedure for measuring pH in Test Tubes (Initial, HCl, NaOH)
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Data and Photos
Presentation of Data
Test Tube
Initial pH
pH after
adding HCl
Difference in
pH (HCl)
pH after
adding
NaOH
Difference in
pH (NaOH)
5 ml
Distilled
Water
7.20
3.82
-3.38
9.50
+2.30
5 ml 2% Egg
Albumin
7.25
3.74
-3.51
9.55
+2.30
5 ml
Phosphate
buffer
6.85
6.57
-0.28
8.14
+1.29
5 ml 0.1M
KCl
7.37
2.90
-4.47
8.84
+1.47
5 ml Distilled Water:
-
Initial pH
- pH after adding HCI
-pH after adding NaOH
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5 ml 2% Egg Albumin:
- Initial pH
- pH after adding HCI
-pH after adding NaOH
5 ml phosphate buffer:
- Initial pH
- pH after adding HCI
-pH after adding NaOH
5 ml 0.1M KCI
- Initial pH.
- pH after adding HCI
-pH after adding NaOH
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Analysis
● Distilled water
Based on the conducted experiment, when the hydrochloric acid (HCl) was added
to the distilled water, the pH decreased from 7.20 to 3.82. Making the water much more
acidic. This shows that the acid greatly increased the amount of hydrogen ions in the
solution. On the other hand, when the base (NaOH) was added, the ph increased from
7.20 to 9.50. Indicating that the solution became more basic. This rise in pH shows that
the base significantly increased the concentration of hydroxide ions in the solution. In
summary, distilled water responded significantly to both the acid and the base,
demonstrating its limited capacity to stabilize pH changes.
● 2% Egg albumin
The results of the experiment showed that the pH level of egg albumin when
adding hydrochloric acid decreased from 7.25 to 3.74. According to Libretexts. (2023),
strong acids such as HCl, decrease the pH level of solutions and with the egg albumin
having a neutral pH of 7.25 reacted strongly to HCl thus decreasing its pH level. Adding
NaOH to the egg albumin instead, showed the pH level increasing from 7.25 to 9.55. In a
study conducted by Yavuz, K., & Özcan, M. M. (2016), the use of NaOH in raising the
pH level of egg whites even at increasing low quantities, which was evident in the results
of our experiment.
● Phosphate buffer
Based on the data, the phosphate buffer, which was made from a mixture of 0.2M
NaH2PO4 (sodium dihydrogen phosphate) and 0.2M Na2HPO4 (disodium hydrogen
phosphate), showed a clear response to the addition of acid and base. When the acid
(HCl) was added, the pH slightly decreased from 6.85 to 6.57. This indicates that the
buffer was able to absorb most of the acid, allowing only a small drop in pH. However,
when the base (NaOH) was added, the pH increased from 6.85 to 8.14, which is a more
significant change. This suggests that the buffer wasn't as effective in absorbing the base,
leading to a larger rise in pH. Overall, the phosphate buffer did a better job at resisting pH
changes when an acid was added compared to when a base was added.
● Potassium chloride (KCl)
Based on the data, KCl showed a significant change in pH when an acid or base
was added. The pH initially measured at 7.37. After adding HCl, the pH dropped
drastically to 2.90, indicating a strong response to the acidic component. This large
decrease suggests that KCl does not effectively buffer against acids. When NaOH was
added, the pH increased to 8.84, showing that the solution also responded noticeably to
the base, though less dramatically than to the acid. This behavior suggests that KCl, while
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stable at its initial pH, is not resistant to pH changes when exposed to acidic or basic
substances.
Answers to Questions
1. What is the importance of having buffers?
Buffers are important in this experiment because they maintain a stable pH environment
in the solutions being tested. This stability is important for accurately measuring the effects of
adding strong acids (HCl) or strong bases (NaOH) to the solutions. Without buffers, the pH could
fluctuate widely, making it difficult to observe the specific effects of the acids and bases on the
different substances, such as egg albumin and KCl.
2. What is the difference of a weak acid and a strong acid?
A strong acid, like HCl used in this experiment, fully dissociates in water, releasing all of
its hydrogen ions and significantly lowering the pH of the solution. In contrast, a weak acid only
partially dissociates in water, meaning it releases fewer hydrogen ions, resulting in a less drastic
change in pH. This distinction is important in the experiment because the behavior of weak acids
as part of the buffer solution helps to prevent sudden changes in pH when strong acids or bases
are added.
3. Why are weak acids used as buffers?
Weak acids are used as buffers in this experiment because they can resist changes in pH
when strong acids or bases are added. By only partially ionizing, weak acids in the buffer
solution can neutralize small amounts of added HCl or NaOH, maintaining the pH at a relatively
stable level. This buffering action is essential for observing how different substances react to pH
changes in a controlled manner, without the pH shifting too drastically.
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References
Admin. (2023, January 17). Buffer - Chemistry - Definition, Types, Examples, Buffer Actions,
Hendersion’s
Equation
with
Videos
and
FAQs.
BYJUS.
https://byjus.com/chemistry/buffer/
Libretexts. (2022a, August 20). 7.1.1: Factors affecting enzyme activity. Biology LibreTexts.
https://bio.libretexts.org/Courses/Prince_Georges_Community_College/PGCC_Microbio
logy/07%3A_Microbial_Metabolism/7.01%3A_Introduction_to_Metabolism_and_Enzy
mes/7.1.01%3A_Factors_Affecting_Enzyme_Activity
Libretexts. (2023, July 12). 16.4: Strong acids and strong bases. Chemistry LibreTexts.
Retrieved
from
https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_General_Chemistr
y_(Petrucci_et_al.)/16%3A_Acids_and_Bases/16.4%3A_Strong_Acids_and_Strong_Bas
es
Mohan, C., Ph.D., (2006). Buffers. A Guide for the Preparation and Use of Buffers in Biological
Systems.
https://www.researchgate.net/publication/255703448_Buffers_A_Guide_for_the_Prepara
tion_and_Use_of_Buffers_in_Biological_System
Mutedzi, T. (2019, November 21). Buffer Solution - Acidic and Basic Buffers, Preparations,
Examples. BYJUS. https://byjus.com/jee/buffer-solutions/
Pietri, J., & Land, D. (2017, February 13). Introduction to Buffers. Chemistry LibreTexts.
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_
Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/
Buffers/Introduction_to_Buffers#:~:text=A%20buffer%20is%20a%20solution
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Yavuz, K., & Özcan, M. M. (2016). The effect of NaOH on the performance of the pasteurized
liquid egg white. Journal of Agroalimentary Processes and Technologies, 22(1), 43-45.
Retrieved
from
https://journal-of-agroalimentary.ro/journal-of-agroalimentary-processes-and-technologie
s-2016-22-1/the-effect-of-naoh-on-the-performance-of-the-pasteurized-liquid-egg-white
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