Preparation and Standardization of a Sodium Chloride (NaCl) Solution

Abstract

The aim of this experiment was to prepare a standard solution of a given salt by accurately measuring the mass of the substance and transferring it to a volumetric flask to achieve a specific concentration. The molar mass of the substance was determined, and the required mass was calculated using the formula: Mass = moles × molar mass. The solution was prepared step by step, following precise techniques. The final solution was carefully mixed and labeled with the substance name and its concentration.

Introduction

In analytical chemistry, a standard solution is a solution with a precisely known concentration of an element or substance, typically expressed in mol/dm³. When preparing a standard solution, it is crucial to accurately measure the correct mass of the substance and ensure that it is completely transferred to the volumetric flask, maintaining the desired concentration.

Procedure

Step 1: Calculate the number of moles needed to create the solution with the required volume and concentration using the formula: \( \text{Moles} = \text{concentration} \times \text{volume (dm}^3\) \).

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Step 2: Determine the molar mass of the substance and calculate the mass required for the desired volume using the formula: \( \text{Mass} = \text{moles} \times \text{molar mass} \).

Steps 1 and 2 must be completed before proceeding to the following steps.

Step 3: Place a watch glass on the mass balance and record its initial mass.

Step 4: Carefully weigh out the required mass of the substance by difference of mass.

Step 5: Slowly add the solid substance to a small beaker and dissolve it in distilled water.

Step 6: Position the watch glass over the beaker and rinse any residual solid particles into the beaker with distilled water.

Step 7: Transfer the solution from the beaker to a volumetric flask using a dry funnel, ensuring a small air gap around the funnel's step inside the neck of the flask.

Step 8: Gradually add distilled water through the funnel until the water level in the volumetric flask reaches the base of the neck. Carefully add more distilled water until the meniscus is approximately 2 cm below the graduation mark on the neck. Remove the funnel.

Step 9: Use a Pasteur/dropper pipette to add distilled water drop by drop to the volumetric flask until the bottom of the meniscus aligns with the graduation mark on the neck when viewed at eye level. If the water level exceeds the mark, restart from Step 3.

Step 10: Stopper the volumetric flask and invert it several times to ensure thorough mixing.

Step 11: Label the volumetric flask with the name of the substance and its concentration.

Results

Discussion

The experimental procedure was followed meticulously, resulting in the successful preparation of a standard solution with the desired concentration of sodium chloride (NaCl). The accuracy of the mass measurements and the thorough mixing of the solution were crucial in achieving the desired outcome. Any deviation in these steps could lead to inaccuracies in the final concentration.

Conclusion

In conclusion, this experiment effectively demonstrated the preparation of a standard solution by accurately measuring the mass of sodium chloride (NaCl) and ensuring its transfer to a volumetric flask. The final solution was mixed thoroughly and properly labeled with the substance name (NaCl) and its concentration (0.100 mol/dm³). These precise techniques are essential in analytical chemistry to obtain reliable and consistent results for various analytical applications.