Experiment 1
OBJECTIVE
TO PREPARE THE PRIMARY STANDARD DECINORMAL SOLUTION Of SODIUM CARBONATE IN 250 ML
APPARATUS REQUIRED
- Pipette
- Beakers
- Conical flask
- Volumetric flask
CHEMICAL REQUIRED
Na2CO3
THEORY
Anhydrous sodium carbonate is a primary standard substance used to prepare the primary standard solution. The solution which is prepared by dissolving the exact weight of the primary standard substance in solvent and making a definite volume is called a primary standard solution. Anhydrous Na2CO3 has an equivalent weight of 53. The wt of anhydrous Na2CO3 required to prepare 250ml of N/10 (decinormal solution) is calculated by the formula:
Weight\ Required\ (W) = \frac{VEN}{1000}\\ W = \frac{250 \times 53 \times 0.1}{1000} = 1.325 \text{ gm}
Therefore, 1.325 gm of Na2CO3 is required to prepare 250 ml of decinormal solution.
PROCEDURE
Accurately, 1.325 g of anhydrous Na2CO3 is weighed out in chemical balance. The salt was transferred
into the 250 ml of volumetric flask with the help of a funnel. The particles were washed down into the
volumetric flask by water & dissolved all the salt in a minimum amount of water with constant shaking.
The solution was made up to the mark by adding water so that the lower meniscus coincides with the
line. The flask is closed by using a lid.
OBSERVATION
\begin{align*} \text{Normality factor(f)}&=\frac{\text{wt taken}}{\text{wt. to be taken}}\\ &=\frac{1.32}{1.325}\\ &=0.996\\ \text{Actual normality}&=0.1\times f\\ &=0.1 \times 0.996\\ &= 0.0996N \end{align*}
RESULT
Hence, the primary standard solution of 250ml of N/10 x f sodium carbonate was prepared.
CONCLUSION
The standard solution of primary standard substances can be prepared by taking exact weight.
PRECAUTIONS
- The weight should be accurately measured.
- Apparatus should be handled carefully.
- Water should be added at the end drop by drop.
- The lower meniscus of the solution should coincide with the mark.