Learn about the preparation and standardization of 0.1 M zinc sulphate solution through a laboratory experiment or practical.
Aim:
To prepare and standardize 0.1 M zinc sulphate solution using standard 0.1M EDTA (Complexometric titration).
Requirements:
Glasswares: Burette, burette stand, conical flask, volumetric pipette, beaker, volumetric flask, funnel, glass rod, and wash bottle, etc.
Chemicals: Zinc sulphate (ZnSO4), disodium edetate (C10H16N2O8), ammonium acetate (C2H7NO2), acetic acid (CH3COOH), and dithizone (C13H12N4S), etc.
Preparation of 0.1 M zinc sulphate solution:
Take properly weighed 28.80 gm of zinc sulphate and dissolve in 800 ml of distilled water, once it has completely dissolved, make up the volume to 1000 ml.
Preparation of acetic acid-ammonium acetate buffer:
Take 07.70 gm of ammonium acetate in 50 ml of distilled water and add 05.70 ml of acetic acid, once it has completely dissolved, make up the volume to 100 ml with 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 10.00 ml of a previously standardized solution of 0.1 M EDTA and pour into a conical flask.
- Add 04.00 gm of ammonium acetate.
- Then add 10.00 ml of acetate buffer and 50.00 ml alcohol.
- Add 02.00 ml of dithizone TS as an indicator and shake well.
- Titrate it with prepared 0.1 M zinc sulphate solution with constant stirring until the endpoint.
- The actual endpoint is indicated by a rose pink color.
- To get accurate results, repeat the titration three times.
- Properly record the readings of the burette.
- Take their mean and calculate the molarity of the zinc sulphate solution.
Observation table:
Sr. No. | Content in conical flask | Burette reading | Volume of titrant used (ml) | |
Initial | Final | |||
1 | | | | |
2 | | | | |
3 | | | | |
| Mean: | |||
Calculations:
1 ml of 0.1 M EDTA is equivalent to 0.02785 g of zinc sulphate.
M = Molarity of EDTA x 10 / reading of the burette
Result:
The strength of the prepared zinc sulphate solution was found to be_____M.
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