Determining Sodium Carbonate Concentration

This document outlines a laboratory experiment designed to calculate the concentration of sodium carbonate (Na2CO3) solution. The experiment involves titrating an unknown concentration of Na2CO3 solution with a standardized solution of hydrochloric acid (HCl) until the endpoint is reached, indicated by a color change. Using the known concentration and volume of HCl consumed, the moles of Na2CO3 can be calculated, allowing for the determination of its concentration. The experiment also discusses potential sources of error and emphasizes the importance of precision in measurements.

Running head: CHEMISTRY 0
CHEMISTRY
Name of Student
Institution Affiliation

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Experiment: PREPARATION OF SODIUM CARBONATE SOLUTION AND ACID-
BASE TITRATION
Materials used
Solid Sodium Carbonate,
Distilled Water
Diluted Hydrochloric acid
Phenolphthalein indicator
PART A: PREPARATION OF SOLUTION
I. OBJECTIVES
To prepare accurately a solution of sodium carbonate Na2CO3, starting with a pure solid sodium
carbonate.
II. BACKGROUND
Anhydrous sodium carbonate of analytical reagent quality can be used as a primary standard as it
can be obtained very pure and does not readily pick up moisture from the air. By dissolving a
precisely known mass of Na2CO3 in a definite volume of solution, it is possible to prepare a
standard solution of Na2CO3 that is one whose solution is known exactly (Csuros, 2012).

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PROCEDURE
Weighing boats 1.3g to 1.4 g of Na2CO3 were accurately weighed and the correct weighed
amount was noted down. 100 mL volumetric flask was rinsed clean with a reasonable amount of
distilled water (John C. Kotz, 2014). Sodium carbonate was transferred into this volumetric flask
using a spatula or a filter funnel. Solid Na2CO3 with distilled water in volumetric flask was
dissolved and the flask was filled to approximately a quarter full with distilled water then stopper
was used and it was shaken well to enable it to dissolve. Distilled water was added to just below
the calibrated mark. Pasteur pipette was used to add the final volume of water drop- wise so that
the bottom of the meniscus is on the calibration line (Lambert, 2013). The stopper of the flask
was inverted 15 times so that the solution is homogeneous and the solution was labeled.
Calculating the concentration of the prepared solution.
Mass of the Na2CO3 = 1.4 g
Molar mass of Na2CO3 = 106
Number of moles of Na2CO3 = Mass of Na 2CO 3
molar mass of Na 2CO 3
Number of moles = 1.4
106 = 0.0132 moles
Concentration of Na2CO3 (grams/liter) = grams of Na 2CO 3
volume of t h e solution( L)

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Concentration in grams per liter = 1.4
0.025 (¼ of 100 mL)
Concentration of Na2CO3 = 56 g/ liter
Concentration of Na2CO3 (moles/liter) = moles of Na2 CO 3
volume of t h e solution( L)
Concentration in grams per liter = 0.0132
0.025
Concentration of Na2CO3 = 0.5283 M (moles / liter)
Concentration of Na2CO3 (ppm) = grams of Na2 CO 3∈mg
volume of t h e solution(L)
Concentration in ppm = 0.0014
0.025
Concentration in ppm = 0.056
Concentration of Na2CO3 ( ppb) = grams of Na2 CO 3∈μg
volume of t h e solution( L)
Concentration in ppb = 0.0000014
0.025

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Concentration in ppb = 0.000056
Concentration of Na+ (ppm) = grams of Na+ ¿
volume of t h e solution∈L ¿
Concentration in ppm = 0.0014
0.025
Concentration in ppm = 0.056
Concentration of CO32+ (ppm) = grams of Ca2+ ¿
volume of t h e solution∈ L ¿
Concentration in ppm = 0.0014
0.0 25
Concentration in ppm = 0.056
PART B : DILLUTION OF A Na2CO3 SOLUTION
I. OBJECTIVE
To accurately dilute a solution of sodium Carbonate
II. PROCEDURE
A clean dry 20 mL volumetric pipette and 250 mL volumetric flask were obtained. Na2CO3
Solution from part A was poured into a 250 mL clean dry beaker. The volumetric pipette was

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rinsed with a small amount of Na2CO3 solution (Murthy, 2011). The volumetric pipette was used
to transfer 80mL of original solution into a 250 mL volumetric flask. Approximately three-
quarter of the flask was filled with distilled water, then it was shaken well to mix. More water
was added to just below the calibration mark (Oriakhi, 2011). Pasteur pipette was used to add the
final volume of water drop-wise so that the bottom of the meniscus is on the calibration line. The
flask was stopped and inverted a number of times so that the solution is homogeneous
(Townsend, 2015).
CALCULATION
Number of moles of Na2CO3 removed from the original solution= Molarity ×Volume (L)
= 0.5283 × 0.025
= 0.0132 moles
Number of moles Na2CO3 of in diluted solution = Number of moles removed from the original
solution
The moles will never change of dilution what will change is molarity. Therefore the number of
moles will remain 0.0132.
Concentration of the diluted solution (moles/liter) = moles of Na2 CO 3
Volume of t h e substance∈ L
Concentration of Na2CO3 = 0.0132
0.1875 = 0.0704 M
PART C: TITRATION OF Na2CO3 SOLUTION WITH STANDARD HCI SOLUTION

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I. BACKGROUND
HCl can be used as a primary standard. In this experiment, you will use an approximately 0.05
mol-1 solution of HCl and determine the exact concentration of Na2CO3 by titrating the HCl
solution against the Na2CO3 solution prepared in part B (Townsend, 2015).
When HCl is added to Na2CO3, it will react according to the following equation:
2HCl + Na2CO3 2 NaCl +H2O+ CO2
An indicator, phenolphthalein is used to indicate when all the Na2CO3 has been converted to
NaCl. At this point, the number of moles of HCl added is exactly double the number of moles of
Na2CO3.In this experiment the concentration of HCl is known hence we will be required to
obtain the concentration of Na2CO3 through calculation (Lambert, 2013).
II. OBJECTIVES:
The objective of this part is to check on the accuracy of the solutions. One of the simplest way to
determine the concentration of the dilute Na2CO3 solution by titration with standardized HCl
(Murthy, 2011).
III. PROCEDURE
100mL of HCl was approximately obtained in the beaker and its exact concentration was
recorded. The beaker is rinsed with a little solution of HCl if it is wet. The burrete was rinsed
with some of the HCl solutions and then the burette was filled with HCl. The volume of HCl
was recorded as the `` initial volume `` in the result table below. A 20 mL or 25 mL pipette was
rinsed clean with some of the Na2CO3 solutions 20 mL or 25 mL of the part B Na2CO3 was
pipetted into a 250 mL conical flask (John C. Kotz, 2014). The volume of the Na2CO3 used was

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noted in the table below (Townsend, 2015). 3 drops of phenolphthalein were added as the
indicator to the sample. The conical flask containing the dilute Na2CO3 was placed on a white
piece of paper beneath the burette and titrated until the diluted red-purple Na2CO3 just become
permanently colorless. The level of the HCl acid in the burette was noted and recorded in the
table shown below under final reading. The titration volume will be equal to the initial reading
minus the final reading (Townsend, 2015). The titration was repeated with a further amount of
Na2CO3 samples until consistent titration volume is obtained.
IV. RESULTS
Sample
number
Sample Volume of sample
(mL)
Burette
solution
Initial
reading (mL)
Final reading
( mL)
Titration volume ( mL)
1 Na2CO3 25.54 HCl 0.00 25.54 25.54
2 Na2CO3 25.32 HCl 0.00 25.32 25.32
3 Na2CO3 24.96 HCl 0.00 24.96 24.96
V. CALCULATIONS:
Average volume of HCl is 25.54+25.32+24.96
3 = 25.27 mL
Chemical equation between HCl and Na2CO3
2HCl + Na2CO3 2 NaCl +H2O+ CO2

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From the equation above the mole ratio between HCl : Na2CO3 is 2:1
The number of moles of HCl = Molarity of HCl × Volume of HCl
Moles of HCl = 0.05 × 0.02527
Moles of HCl= 0.00126 moles
Therefore the moles of Na2CO3 = 0.00126× ½
Moles of Na2CO3 = 0.000631 moles
Concentration of Na2CO3 = Moles of Na 2CO 3
Volume of Na2 CO 3 sample ∈L
Concentration= 0.000631
0.025
Concentration= 0.02524M
Concentration of Na2CO3 = Moles of Na 2CO 3× molar mass of Na2 CO 3
Volume of Na2 CO 3 sample L
Concentration = 0.00631× 106
0.025
Concentration = 0.066886
0.025
Concentration = 2.67544 g/L
DISCUSSION

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The values of the volume of the HCl used in this during the titration when it was reacted with
Na2CO3 was obtained as roughly 25mL as this volume had a consistency of ranging from 25.54,
25.32 and 24.96 for the last experiment trial. For each and every experiment our initial reading
started from zero, this is because the burette was refilled to zero mark after every trial. This helps
to avoid some errors which may arise due to substruction of final volume from initial volume .
The results obtained are very correct but in some cases, errors can lead to incorrect values due to
inaccuracy during the practical. On the values obtained from the part, C and those calculated
from part B are almost similar but there is a slight difference due to the accuracy errors during
the conduction of the practical. The value of the molarity of Na2CO3 in part B is 0.0704 M while
that in part C is 0.025 M. In terms of concentration in moles per liter (molarity) these are almost
similar values since the variation is very small (Oriakhi, 2011). The variation occurs due to
wrong values obtained (read) during the practical. Some error may arise due to inaccuracy in
noticing the exact point when the color change during the practical. At the point when the color
change is the endpoint of the reaction. And this may contribute to the higher probability of this
variation of the two values (Townsend, 2015). These errors can be limited by being keen during
the color change and the experiment should be conducted in a clean environment to ensure that
contaminations are reduced whi1ch can affect the endpoint of this experiment.
CONCLUSION
At the end of the experiment, it was possible to produce the solution of Na2CO3 which was done
by dissolving it in distilled water. The accuracy of the concentration of Na2CO3 was confirmed
using the standardized solution of HCl whose concentration was known. This was possible after
writing a correct chemical equation and a mole ratio of 2:1 was obtained which made it very

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simple to obtain the moles of Na2CO3 since the mole of HCl could be easily calculated from the
concentration and its volume used (Lambert, 2013). After dissolving the solid Na2CO3 its
solution was obtained which was used in the reaction with HCl to help obtain its concentration
since the concentration of HCl was known as 0.05 M.
Reference
Csuros, M. (2012). Environmental Sampling and Analysis: Lab Manual. Colorado: CRC Press.
John C. Kotz. (2014). Chemistry & Chemical Reactivity. New Delhi: Cengage Learning.
Lambert, N. (2013). Practical Chemistry for CSEC: Experiments, Structured Exercises, and Objective
Questions. New York: Heinemann.
Murthy, P. (2011). University Chemistry, Volume 1. Manchester: New Age International.
Oriakhi, C. O. (2011). Chemistry in Quantitative Language: Fundamentals of General Chemistry
Calculations. Hull: Oxford University Press.
Townsend, J. (2015). Chemistry and Chemical Reactivity. Hongkok: Cengage Learning.