Campion College 6B Chemistry ` Laboratory
Name: Ashiekie Hamilton
Date: 20/09/2023
Experiment No. : 1 `
Skill: A/I
Topic: Volumetric Analysis
Aim: To investigate the volume of sodium hydroxide (NaOH) needed to determine the
concentration of 0.025 dm³ of sulphuric acid (H2SO4).
Instructions:
Solution A is a solution containing 0.016M sodium hydroxide.
Solution B is a sulphuric acid solution. You are to determine the concentration of the
sulphuric acid solution.
Pipette 25.0 cm3 of the Solution B into a conical flask, add two drops of phenolphthalein
indicator and titrate it with the solution A from a burette.
Repeat the titration until consecutive volume readings within 0.1 cm3 of each other are
obtained.
Results:
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5
Final Burette 22.80 22.00 22.40 22.70
reading/cm3
Initial Burette 0.00 0.00 0.00 0.00
Reading/cm3
Volume of Solution A 22.80 22.00 22.40 22.70
used /cm3
Calculate:
1. Determine the average volume of solution A required to neutralize 25 cm3 of solution B
[1]
Avg. Vol. = 22.80+22.70/2
Avg. Vol. = 45.5/2
Avg. Vol. = 22.75 cm³
Avg. Vol. = 0.023 dm³
2. The moles of NaOH reacting [1]
Moles = vol. X conc.
Moles = 0.023 x 0.016
Moles = 3.68 x 10-⁴ mol
3. Write a balanced equation for the reaction occurring. [1]
2 NaOH (aq) + H2SO4 (aq) → Na2SO4 (aq) + 2 H2O(l)
4. The moles of H2SO4 present in 25 cm3 of solution B [1]
Moles ratio-
2:1
3.68 x 10-4 : x
x= 3.68 x 10-4/2
x= 1.84 x 10-4 mol
5. The moles of H2SO4 present in 1000 cm3 of solution B [1]
0.025 : 1.84 x 10-4
1:x
x = 1.84 x 10-4/0.025
x = 7.36 x 10-3 mol
6. The mass, in g, of H2SO4 present in 1000 cm3 of solution B [1]
H=1 S=32 O= 16
Mass = moles x molar conc.
Mass = 7.36 x 10-3 x 98
Mass = 0.72 g
Discussion: [2]
Explain the theological principle of titration using your lab.
Titration is used to determine the concentration of an unknown solution by using a solution
of which the concentration is known. The analyte (H2SO4), the unknown, is placed in a
volumetric flask with no more than 2 drops of phenolphthalein indicator while the titrant
(NaOH), the known, is placed in the burette. Phenolphthalein is used in neutralization
reactions and turns pink if the end product is a basic solution. The end point of the reaction
was reached and shows that 0.023 dm3 of NaOH is needed to neutralize 0.025 dm3 of H2SO4.
Sources of Error: (at least 2) [2]
1. Spills when swirling the analyte after adding the phenolphthalein indicator affects the
volume of H2SO4 reacting in the volumetric flask.
2. Slow human reaction time in closing the burette when the end point has been reached.
Precautions: (at least) [2]
1. It was ensured that the burette was read from eye level.
2. It was ensured that the funnel was removed before beginning titration so that the
volume in the burette was not affected.
