Learn about the preparation and standardization of 0.1 M ceric ammonium sulphate through a laboratory experiment or practical.
Aim:
To prepare and standardize 0.1 N ceric ammonium sulphate using arsenic trioxide as primary standard.
Reference: Indian Pharmacopoeia (IP) 2007, Volume-1, Page No.313
Requirements:
Glasswares: Burette, burette stand, conical flask, volumetric pipette, beaker, volumetric flask, funnel, glass rod, and wash bottle, etc.
Chemicals: LR grade ceric ammonium sulphate, arsenic trioxide, potassium iodide, sodium hydroxide, sulphuric acid, osmic acid, ferroin sulphate, and 1, 10-phenanthroline hydrochloride, etc.
Apparatus: Digital/analytical balance, and Ultrasonicator.
Principle:
The titration of ceric ammonium sulphate is based on the redox reaction/titration. Ceric ammonium sulphate solution is directly titrated with standard arsenic trioxide in the presence of sulphuric and osmic acid to determine its strength. Using ferroin sulphate as an indication, the endpoint of the titration is determined by a change in color from pink to very pale blue.
The following is the reaction that is involved in this titration.
The molecular weight of ceric ammonium sulphate((NH4)4Ce(SO4)4)is 632.53 g/mol.
Preparation of ceric ammonium sulphate (0.1 M):
- Take 65.00 gm of ceric ammonium sulphate ((NH4)4Ce (SO4)4), dissolve it in a mixture of 30 ml sulphuric acid and 500 ml of distilled water at a gentle heat.
- Allow the solution to cool to ambient temperature and filter it.
- Make up the volume to 1000 ml with distilled water in a volumetric flask and properly mixed it.
Preparation of dilute sulphuric acid:
Please click here to get the procedure.
Preparation of osmic acid solution:
Take 01.00 g of osmic acid (OsO4) and dissolve it in 100 ml of distilled water in a volumetric flask and properly mixed it.
Preparation of ferroin sulphate solution:
Take 00.70 g of ferrous sulphate (FeSO4) and 1.5 g of 1,10-phenanthroline hydrochloride dissolve it in 100 ml of distilled water in a volumetric flask and properly mixed it.
Preparation of 8 % sodium hydroxide solution:
Weigh 08.00 g sodium hydroxide accurately and pour it into a 100 ml volumetric flask containing 70 ml distilled water and dissolve it well and make up the volume with distilled water.
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.
- Take 00.20 gm of previously dried arsenic trioxide and pour it into a 500 ml conical flask.
- Add 25 ml of 08 % of sodium hydroxide solution and swirl to dissolve.
- After that, add 100 mL of distilled water and mixed thoroughly.
- Add 30 ml dilute H2So4 solution, 0.5 ml osmic acid solution and add 2-4 drops of ferroin sulphate indicator and mixed thoroughly the mixture.
- Titrate the sample solution with ceric ammonium sulphate solution until the endpoint is reached.
- The actual endpoint is indicated by the appearance of a pink color to very pale blue.
- To get accurate results, repeat the titration three times.
- Properly record the readings of the burette.
- Take their mean and calculate the molarity of ceric ammonium sulphate solution.
Observation table:-
|
Sr. No. |
Content
in conical flask
|
Burette
reading |
Volume
of titrant used (ml) |
|
|
Initial |
Final |
|||
|
1 |
|
|
|
|
|
2 |
|
|
|
|
|
3 |
|
|
|
|
|
Mean: |
|||
Calculations:
Molarity of (NH4)4Ce (SO4)4 = 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 (NH4)4Ce (SO4)4 used
For 0.1 M ceric ammonium sulphate the equivalent factor is 0.004946.
Result:-
The strength of the prepared ceric ammonium sulphate solution was found to be_____M.
Commonly asked questions on titration are as follows.
Which primary standard can be used for the standardization of ceric sulphate solution?
Arsenic trioxide (As2O3) is used as the principal standard for standardizing ceric sulphate solutions in the presence of sulfuric and osmic acid, using ferroin sulphate as an indicator.
What is ceric ammonium sulphate?
Ceric ammonium sulphate is an inorganic compound or analyte used in analytical chemistry for redox titration.
How many types of titration are there?
There are four types of titrations in chemistry: acid-base, redox, complexometric, precipitation titrations.
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