Name 1

Name: Amari Patterson
Lab: 9
Date: October 5th 2023
Topic: Quantitative Analysis (Acid-base Titration)
Aim: The aim of this experiment is to find the concentration of a solution of Sodium Hydroxide
by a titration method, using Hydrochloric acid.
Apparatus/Materials: Solution containing approximately 4g dm-3 Sodium Hydroxide, 0.1
mol/dm3 Hydrochloric acid (accurately Standardized), Phenolphthalein indicator, Conical flasks,
50 cm3 burette, 25cm3 pipette and string rood
Procedure:
1. Clean the equipment that needs to be washed, using water/tap water, then with distilled
water and rinse with hydrochloric acid solution.
2. Then pour hydrochloric acid until it reaches the convenient graduation mark on the
burette. Then record your readings.
3. Filter using paper chromatography, 25.0 cm3 of sodium hydroxide solution into a conical
flask
4. Then add 1-2 or 3 drops of phenolphthalein indicator into the conical flask.
5. Slowly add HCl solution from the burette to the conical flask while swirling.
6. Recorded the volume of HCl solution required to reach the endpoint, indicated by a color
change from pink/purple to colorless.
7. Then repeat steps 2-5 two more times.
Observation/Results:
In the conducted experiment, the goal was to determine the concentration of a Sodium
Hydroxide (NaOH) solution through a titration method employing Hydrochloric Acid (HCl). The
procedure began with the preparation of clean and dry glassware, including a rinsed burette filled
with HCl, and a precisely measured volume of the NaOH solution transferred to a conical flask.
A few drops of phenolphthalein indicator were added to the NaOH solution, turning it pink.
During the titration, HCl was slowly added to the NaOH solution in the flask while swirling
continuously. The pink color gradually faded, and at the endpoint, it disappeared, signifying
neutralization. The initial and final volumes of HCl in the burette were recorded. Subsequent
calculations were performed to determine the concentration of the NaOH solution, and the
experiment was repeated for greater accuracy. Finally, the results were recorded and reported.
Table used to record the results obtained from titration:
Burette Readings Rough 1 2
(cm3)
At the end of titration 23.90 20.20 24.50
At the start of 00.00 00:00 00.00

titration
The volume of HCl 22.90 23.60 23.20

used
(cm3)
Discussion:
Titration is a laboratory technique used to determine the concentration of a substance in a
solution. It involves slowly adding a solution of known concentration (the titrant) to another
solution containing the substance of interest (the analyte) until a chemical reaction reaches
completion. The point at which the reaction is complete is termed the "endpoint," often signaled
by a noticeable change in a property of the solution, such as a color change or a pH shift.
Titration is a fundamental and precise method for quantitative analysis in various scientific
fields. The results obtained from a titration are primarily used to determine the concentration of
the analyte in the solution. This information has broad applications in fields like chemistry,
biology, and environmental science. For instance, in an acid-base titration, the concentration of
an acidic or basic substance can be accurately measured. This data is critical in industrial
processes, quality control, and scientific research.
In an acid-base titration such as the one described, the color change at the endpoint is due to the
use of an indicator, phenolphthalein. Initially colorless in basic solutions, phenolphthalein turns
pink in a slightly acidic environment. As Hydrochloric Acid (HCl) is added to Sodium
Hydroxide (NaOH) in the flask and slightly swirling, the pink color begins to fade, and the
endpoint is reached when the pink color disappears completely. This indicates that the solution is
now neutral, and the reaction is complete.
The type of reaction involved in this acid-base titration is a neutralization reaction. In this
process, an acid (HCl) and a base (NaOH) react to form a salt (Sodium Chloride, NaCl) and
water (H₂O). This reaction is often referred to as an acid-base reaction because it involves the
transfer of protons (H⁺ ions) from the acid to the base, resulting in the formation of water and
salt. The symbolic formula for the reaction created is:
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
Conclusion:
Molar concentration= 0.093 mol dm-3
25 cm3 NaOH contains 0.002325 mol NaOH
1000 x 0.002325
= 0.093 mol dm-3
25
Mass concentration= 3.72 gdm-3

M(NaOH) = 23 + 16 + 1= 40gmol
1 mol NaOH= 40g
Mass of concentration= 40 x 0.093
Mass of concentration= 3.72 gdm-3
Treatment of Results:
a. Using the values for the accurate titrations only, find the average volume of Hydrochloric
acid used.
Average Titration= V cm3 of HCl(aq) = 25.0 cm3 of NaOH(aq)

Average Titration= 23.30 cm3 + 23.20 cm3 = 46.50 cm3
Average Titration= 46.50 cm3/2
Average Titration= 23.25 cm3
b. Find the number of moles of hydrochloric acid in the average volume used
No. of mol HCl = Vol. of HCl(aq) × Concentration/1000

No. of mol HCl = (23.25 cm3 x 0.1)/1000
No. of mol HCl = 0.002325 mol HCl
c. From the equation, one mole of HCl (aq) reacts with one mole of NaOH(aq). Use this
information to find the number of moles of NaOH(aq) in 25 cm3 of the solution.
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)
Cross Multiplication:
1mol x 0.00205
x= = 0.002325mol NaOH
1
d. Using your answer to c find the concentration of NaOH aq in both mol dm and gdm
25 cm3 NaOH contains 0.002325 mol NaOH
1000 x 0.002325
= 0.093 mol dm-3
25
Molar concentration= 0.093 mol dm-3
M(NaOH) = 23 + 16 + 1= 40gmol
1 mol NaOH= 40g
Mass of 0.093 mol. NaOH
Mass of concentration= 40 x 0.093

Mass of concentration= 3.72 gdm-3
Reflection:
I have learnt more about the different indicators used in the chemical world. The phenolphthalein
indictor is a known color changer when it comes in contact with an acid or a base. With it comes
in contact with an acid, it has a colorless form. However, it comes in contact with an alkaline, it
changes color to a pink color. Society can learn from this, to assist with identifying acidic and
alkaline substances.
Limitations/Sources of Error:
1. Not reading the measurements correctly from eye level
2. Not correctly using the equipment
Precautions:
1. Do not engage in physical contact with the substances
2. Wear protective gears to help ease the risk of physical contact

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Name: Amari Patterson

At the end of titration 23.90 20.20 24.50

At the start of 00.00 00:00 00.00

The volume of HCl 22.90 23.60 23.20

Mass concentration= 3.72 gdm-3

Average Titration= V cm3 of HCl(aq) = 25.0 cm3 of NaOH(aq)

No. of mol HCl = Vol. of HCl(aq) × Concentration/1000

NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)

25 cm3 NaOH contains 0.002325 mol NaOH

Molar concentration= 0.093 mol dm-3

Mass of concentration= 40 x 0.093

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