Practical Test Revision

KOLEJ MATRIKULASI MELAKA

CHEMISTRY UNIT

LABORATORY REPORT
SK015

TITLE
Determination of the concentration of hydrochloric acid, HCl solution.
OBJECTIVE
To determine the concentration of hydrochloric acid, HCl.
THEORY
Molarity (M) is the common unit used to express the concentration of solutions. Molarity is defined
as the mole of solutes per unit volume of solutions in L.
The concentration of the acid solution can be determined by titrating it with a standard basic solution
with a known concentration. In this experiment, the concentration of hydrochloric acid, HCl, is
determined using sodium hydroxide, NaOH standard solution.

To achieve this, the volume of sodium hydroxide, NaOH solution that is required to exactly neutralise
the hydrochloric acid, HCl will be accurately measured using a burette. The point at which an equal
amount of OH- ion from base and H+ ion from acid react is known as the equivalence point.
An indicator such as phenolphthalein and methyl orange can be used to determine the endpoint of
the titration.

APPARATUS
White tile, Pipette filler, Filter funnel, Retort stand, 250 mL conical flask, 100 mL beaker, 50 mL burette,
25 mL pipette

CHEMICAL REAGENTS
Phenolphthalein, 0.100 M sodium hydroxide, NaOH, x M hydrochloric acid, HCl and distilled water.

PROCEDURE

1. Rinse a burette with distilled water followed by 0.100M sodium hydroxide, NaOH solution.
2. Fill the burette with the same 0.100M NaOH solution. Ensure there are no air bubbles

trapped at its tip.
3. Record the initial burette reading to two decimal places.
4. Rinse a pipette with distilled water followed by hydrochloric acid, HCl solution.
5. Pipette 25 mL of hydrochloric acid, HCl into a conical flask and add two drops of

phenolphthalein.
6. Place a white tile underneath the conical flask.

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7. Titrate hydrochloric acid, HCl with sodium hydroxide, NaOH solution while swirling the flask
continuously.

8. Rinse any titrant on the inner wall of conical flask with distilled water.
9. Upon reaching the end point, dispense the sodium hydroxide, NaOH solution drop by drop.

The end point is reached when one drop of the sodium hydroxide, NaOH solution turns the
entire solution in the flask from colourless to permanent pale pink.
10. Record the final burette reading to two decimal places.
11. Repeat the titration until three consistent readings are obtained.
12. Calculate the molarity of the hydrochloric acid, HCl using the average of the three consistent
readings (±0.10 mL).

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REPORT WRITING

NAME

CLASS

MATRIC Determination of the concentration of hydrochloric acid, HCl solution.
NUMBER
TITLE To determine the concentration of hydrochloric solution.

OBJECTIVE Molarity (M) is the common unit used to express the concentration of
solutions. Molarity is defined as the mole of solutes per unit volume of
THEORY solutions in L.

The concentration of the acid solution can be determined by titrating it with
a standard basic solutionwith a known concentration. In this experiment,
the concentration of hydrochloric acid, HCl, is determined using sodium
hydroxide, NaOH standard solution.

To achieve this, the volume of sodium hydroxide, NaOH solution that is
required to exactly neutralisethe hydrochloric acid, HCl will be accurately
measured using a burette. The point at which an equal amount of OH- ion
from base and H+ ion from acid react is known as the equivalence point.

An indicator such as phenolphthalein and methyl orange can be used to
determine the endpoint of the titration.

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PROCEDURE 1. A burette was rinsed with distilled water followed by 0.100M sodium hydroxide,
NaOH solution.

2. The burette was filled with the same 0.100M NaOH solution. There were no air
bubbles ensured trapped at its tip.

3. The initial burette reading was recorded to two decimal places.
4. A pipette was rinsed with distilled water followed by hydrochloric acid, HCl solution.
5. 25 mL of hydrochloric acid, HCl was pipetted into a conical flask and two drops of

phenolphthalein were added.
6. A white tile was placed underneath the conical flask.
7. Hydrochloric acid, HCl was titrated with sodium hydroxide, NaOH solution while

swirling the flask continuously.
8. Any titrant on the inner wall of the conical flask was rinsed with distilled water.
9. Upon reaching the end point, the sodium hydroxide, NaOH solution was dispensed

drop by drop. The end point was reached when one drop of the sodium hydroxide,
NaOH solution in the flask was turned from colourless to permanent pale pink.
10. The final burette reading was recorded to two decimal places.
11. The titration was repeated until three consistent readings are obtained.
12. The molarity of the hydrochloric acid, HCl was calculated using the average of the
three consistent readings.

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RESULTS/ The tabulated results show the titration between 25 mL hydrochloric acid, HCl solution

OBSERVATION and 0.100 M sodium hydroxide, NaOH solution.

1. The diagrams of the burette below indicate the gross readings.

Gross reading

0.10 mL

26.80 mL

initial final

2. Record the results by completing the gross readings and the volumes of NaOH
used as in the table.

Burette Gross I II III
reading, mL
Final reading 26.80 30.30 46.00 41.70
Initial reading 0.10 5.00 20.70 16.30
26.70 25.30 25.30 25.40
Volume of
NaOH, mL

CALCULATION 1. Calculate the average volume of NaOH used in experiment.

Average volume = 25.30 mL + 25.30 mL + 25.40 mL
__________________________
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= 25.33 mL

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2. Determine the number of mole of NaOH used in the experiment
Mole of NaOH = (0.100 molL-1)(25.33 x 10-3 L)

= 2.533 x 10-3 mol

3. Write the chemical equation between HCl and NaOH
NaOH + HCl → NaCl + H2O

4. Determine the number of mole of HCl used in this experiment.
From the equation,

1 mole of NaOH Ξ 1 mole of HCl
2.533 x 10-3 mol of NaOH = 2.533 x 10-3 mol of HCl

5. Calculate the molarity of HCl used in this experiment.


=
2.533 10−3

= 25 10−3
= 0.1013 M

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DISCUSSION Based on the experiment, the volume of NaOH used to neutralize the HCl solution is
25.33 mL, while the molarity of HCl obtained is 0.1013 M due to some errors occurred.

Error Precaution steps
1. 1.

2. 2.

CONCLUSION The molarity of HCl solution is 0.1013 M.

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