Group 3: Juarez, V. & Somozo, B.D.M.H.
April 24, 2015
CHEM 14.1, FAB1
May 10, 2015
Experiment No. 7 Acids, Bases and Salts
ABSTRACT
Analytical chemistry is the science of obtaining, processing, and communicating information about the composition and structure of matter. In other words, it is the art and science of determining what matter is and how much of it exists 2. Quantitative Analysis, a chemical analysis under Analytical Chemistry is performed to accurately accurately determine determine the concentration, concentration, amount amount or percentage percentage of one or more elements elements in a test sample5, was used for this experiment. Acid-Base Titration, usually used to find the amount of a known acidic or basic substance through acid base reactions 1, was the method of quantitative analysis done in this experiment. Initially, the 0.1M NaOH titrant was prepared by diluting 10mL 1M NaOH to 100mL distilled water. The three trials of analytes were prepared by diluting 2mL of Silver Swan vinegar to 50mL distilled water. 2 drops of Phenophthalein Phenophthalein was then added to each trial. In order to reach the point of neutralizatio neutralization, n, 15.5mL, 15.5mL, 14.6mL, and 14.5mL 14.5mL of the titrant titrant was used. used. The calculate calculated d concentrations of each trial are 0.775M, 0.73M, and 0.725M. Their average of 0.743M is close to the
theoretical molarity of vinegar with a percent error of 0.93%
sample 5, was used for this experiment.
INTRODUCTION
Acid-
Base Titration was the method of quantitative Analytical chemistry is the science of obtaining,
analysis done in this experiment. Acid-Base
processing, and communicating communicating information
titrations are usually used to find the amount of a
about the composition and structure of matter. In
known acidic or basic substance through acid
other words, it is the art and science of
base reactions. reactions. The analyte (titrand) is the
determining what matter is and how much of it
solution with an unknown molarity. The reagent
exists2.
the
(titrant) is the solution with a known molarity that
constituents of a solution in order to better
will react with the analyte 1. The concentration of
understand the characteristics of the solution.
a certain substance can affect its strength and how
Quantitative Analysis, a chemical analysis under
the substance may react in further chemical
Analytical Chemistry is performed to accurately
reactions. It also affects the characteristics of the
determine
substance.
It
is
the
necessary
to
concentration,
determine
amount
or
percentage percentage of one or more elements in a test
And
knowing
a
substance’s
concentration can help equip one with the 1
knowledge of how to properly handle the
RESULTS AND DISCUSSION
substance. Objectives of this experiment were the proper preparation preparation of the reagent via dilution,
Results
determination of the endpoint of an acid-base titration, and determination of the concentration
15.5mL, 14.6mL, and 14.5mL of the titrant was
of acetic acid in vinegar 3.
needed in order to reach endpoint. The calculated concentrations from these values were 0.775M, 0.73M, and 0.725M respectively. The average of
EXPERIMENTAL PROCEDURE
concentration of the three trials is 0.743M. Initially, preparation of the 0.1M NaOH titrant
Percent error was 0.93%.
from an available concentration of NaOH was done. The available concentration of NaOH was
Discussion
1M. Approximately 10mL of 1M NaOH was diluted to 100mL distilled water to make a 0.1M
According to the data, average acetic acid
solution of NaOH. This solution was used in the
concentration was roughly around 0.743M, which
proceeding steps.
meets
the
federally
required
minimum
concentration of 4 g of acetic acid per 100 mL Next was the titration procedure. The buret was
(0.667M or 0.7M.) of vinegar 6. It was also close
thoroughly rinsed with NaOH. Then, it was filled
to the theoretical molarity of Silver Swan vinegar,
with the prepared 0.1M NaOH solution and the
which is 0.750M. It is important that the air space
air space at the tip was removed. It was set to zero
at the tip of the buret is removed for the volume
reading and then clamped to the iron stand. 2mL
of the reagent will be compromised. Washing and
of the acid from the sample, vinegar of the brand
rinsing the buret afterwards with the prepared
Silver Swan, was transferred transferr ed via pipet to a 100mL
solution will ensure that the buret has the least
Erlenmeyer flask. 50mL of distilled water and 2
possibility
drops of phenolphthalein was added to the flask
chemicals. Titration is relevant since it is used to
with the diluted acetic acid. The acid was then
find the concentration of the test substances 1.
titrated
the
Percent error was 0.93%. Possible source of error
appearance of a permanent light pink coloration.
was inaccurate measurement of the volumes of
The final reading of the buret was recorded. The
the substances to make the reagent, namely 1M
buret was was re-filled re-filled to the zero zero reading reading for the next
NaOH
trials. 3 trials were made. The concentration of the
inconsistencies in the resulting concentration.
analyte was calculated and averaged. Percent
Another is the possibility that distilled water in
error was also noted.
the titrand may have reacted with CO2 in the
with
the
prepared
base
until
of
and
contamination contamination
distilled
from
water,
other
causing
2
atmosphere or may already have carbon dioxide
Percent Error
in it4 forming carbonic acid, which may have
− .74 ×100=0.93% % = .75.75
affected the results.
CONCLUSION AND RECOMMENDATION RECOMMENDATION Calculations
The final concentrations of acetic acid of the three
=
trials with 15.5mL, 14.6mL and 14.5mL 0.1M
( () )( )( )( )( ) ) ( ) )( () )
NaOH used in the experiment experiment are are 0.775M, 0.775M, 0.73M and 0.725M respectively. Their average of
% ℎ | ×100 = |ℎ ℎ
0.743M is close to the theoretical molarity of 0.750M. Percent error is 0.93%. The objectives were met. Though it would be recommended that a more accurate measurement of the substances
Trial 1
used to prepare the reagent be done. Ensuring Ensur ing that
=
(.55 ) ). ( ) ) ( ( ) )(.2 )
the water used in the solutions is as free from
=
. Trial 2
=
(.46 ) ). ( ) ) ( = ( ) )(.2 )
. Trial 3
=
(.45 ) ). ( ) ) ( = ( ) )(.2 )
.
carbon dioxide4 or any other compound that might affect its pH is also imperative to lessen the chance of error.
REFERENCES
(1)Acid-Base
Titrations.
http://chemwiki.ucdavis.edu/Analytical_Chemist ry/Quantitative_Analysis/Titration/AcidBase_Titrations (accessed May 7, 2015).
(2)Analytical
Chemistry.
http://www.acs.org/content/acs/en/careers/colleg e-to-career/areas-of-chemistry/analyticalchemistry.html (accessed May 7, 2015).
Average Molarity of CH 3COOH
. = .775+.7+.725 =.
(3)Committee on General Chemistry. Acids, Bases and Salts. In Laboratory Manual in General
3
Chemistry 1, 2012th ed.; Committee on General Chemistry: Manila, 2012; pp 65-70.
(4)Stoichiometry (4)Stoichiometry in Solution – Solution – Standardization Standardization of Sodium Hydroxide. Macalester College Web site. http://www.macalester.edu/~kuwata/Classes/200 405/chem%20111/111l%20experiment%208%20%20naoh.pdf (accessed May 8, 2015).
(5)Quantitative
Chemical
Analysis.
http://www.labtesting.com/services/materialstesting/chemical-analysis/quantitative-chemicalanalysis/ (accessed May 7, 2015).
(6)The
Analysis
of
Vinegar.
http://wwwchem.csustan.edu/consumer/vinegar/ analysis.htm (accessed May 8, 2015).
“I hereby certify that I have given a substantial contribution to this report and I did not copy and/or quote from any resource material unless being cited as reference. I am make known that failure to accomplish accomplish the second second clause clause would be grounds for plagiarism plagiarism and a failing grade for my final lab report.” report.”
Beah Davee Marie H. Somozo, 2014-35733
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