Learn about the preparation and standardization of 0.1 M sulphuric acid through a laboratory experiment or practical.
Aim:
To prepare and standardization of 0.1 M sulphuric acid (H2SO4) using the primary standard sodium carbonate.
Reference:
- Practical pharmaceutical analysis, by Dr. G. Devala Rao
- Indian Pharmacopoeia (IP), 2007, volume-1, page No.316
Requirements:
Glasswares: Burette, burette stand, conical flask, volumetric pipette, beaker, volumetric flask, funnel, glass rod, and wash bottle, etc.
Chemicals: LR grade sulphuric acid (H2SO4), anhydrous sodium carbonate (Na2CO3), and methyl red or methyl indicator, etc.
Apparatus: Digital/analytical balance, and ultrasonicator.
Principle:
Sodium carbonate is directly titrated with sulphuric acid to determine its strength. Using methyl orange or methyl red as an indication, the endpoint of the titration is determined. The following is the reaction that is involved in this titration.
The molecular weight of sulphuric acid(H2SO4) is 98.07 g/mol.
Preparation of 0.1 M sulphuric acid:
- Take 05.40 ml of sulfuric acid using a pipette, dilute in 1000 ml of distilled water in a volumetric flask, and properly mixing it.
- Otherwise, Calculate the volume of concentrated solution needed and dilute it with distilled water to 1000 ml.
Required volume of concentrated solution= M x MR x 100/ C x SG
Where,
M is a molecular weight
MR is molarity required
C is the concentration or strength of a given solution
SG is a specific gravity
Titration procedure:
- All glassware should be cleaned and dried according to standard laboratory procedures.
- Before filling the burette for the titration, rinse it with distilled water and then pre-rinse it with a portion of the titrant solution. Pre-rinsing is required to make sure that all solution in the burette is the desired solution, not a contaminated or diluted solution.
- Take the unknown stock solution of titrant in a clean and dry beaker then fill the burette using the funnel.
- Remove air bubbles from the burette and adjust the reading to zero.
- Accurately weigh 0.3 gm of previously anhydrous sodium carbonate and pour into a conical flask.
- To dissolve adequately, add 20 ml distilled water and sonicate for 5 minutes on a sonicator.
- Add 2 drops of methyl orange or methyl red indicator once it has been solubilized.
- Titrate the sample solution with H2S04 until the endpoint is reached.
- The temporary appearance of a pink color that fades when the solution is heated to boiling indicates the approach of the endpoint.
- Cool and resume titration until a pink color form that lasts more than 30 seconds and is unaffected by continued boiling, which indicates the actual endpoint of the titration.
- To get accurate results, repeat the titration three times.
- Properly record the readings of the burette.
- Take their mean and calculate the molarity of H2SO4.
Observation table:-
|
Sr. No. |
Content in conical flask
|
Burette reading |
Volume of titrant used (ml) |
|
|
Initial |
Final |
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|
1 |
|
|
|
|
|
2 |
|
|
|
|
|
3 |
|
|
|
|
|
Mean: |
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Calculations:-
Molarity of H2SO4 = W x RM / V x E
Where,
W is a weight of primary standard
E is an equivalent factor of primary standard
RM is a required molarity
V = volume of H2SO4 used
For 0.1 M H2SO4, the equivalent factor of PHP is 0.01059.
Result:-
The strength of the prepared sulphuric acid solution was found to be_____M.
Commonly asked quetions on titration are as follows.
What is standardization?
Standardization is the process in which the accurate molarity of a solution is determined.
What are the types of titration?
Acid-base, redox, complexometric, and precipitation titrations are types of titration that are based on the chemical reaction that occurs between the titrant and the solute or analyte.
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