Preparation of Decinormal Solution of Sodium Carbonate
Apparatus Required
- Beaker
- Conical flask
- Volumetric flask
- Pipette
- Chemical balance
Chemicals Used
- Anhydrous sodium carbonate
- Distilled water
Theory
Anhydrous sodium carbonate is a primary standard substance that can be accurately weighed to prepare a primary standard solution. The weight of sodium carbonate required to prepare 250 ml of decinormal solution is calculated as follows:
Given: 1000 ml of 2N solution of Na₂CO₃ contains 53 g of it.
For 250 ml of 1N solution: (53/1000) * 250 g
For 250 ml of 0.1N solution: (53/1000) * 250 * 0.1 g
Weight required = 1.325 g
Procedure
- Accurately weigh 1.325 g of anhydrous sodium carbonate using a chemical balance.
- Transfer the weighed salt into a 250 ml volumetric flask using a funnel.
- Wash down the particles into the flask with water and dissolve the salt in a minimum amount of water with constant shaking.
- Fill the flask with water up to the mark, ensuring the lower meniscus coincides with the line. Close the flask with a lid.
Observation
| Description | Value |
|---|---|
| Weight of empty watch glass (W1) | W1 |
| Weight of watch glass + sodium carbonate (W2) | W2 |
| Weight of sodium carbonate | W2 - W1 = 1.325 g |
| Volume of water | 250 ml |
| Normality factor | 1 |
Result
The primary standard 250 ml decinormal solution of sodium carbonate was successfully prepared.
Conclusion
Standard solutions of primary standard substances can be accurately prepared by weighing the exact amount.
Precautions
- The weight should be measured accurately.
- Handle apparatus with care.
- Add water drop by drop at the end.
- Ensure the lower meniscus of the solution coincides with the mark.