In chemistry, the preparation of solutions with specific concentrations is a crucial aspect of many experiments. One such commonly used chemical is sodium chloride (NaCl). NaCl is an essential compound that finds its use in various chemical and biological experiments. It is often necessary to prepare NaCl solutions of specific concentrations for such experiments. In this article, we will discuss the procedure for preparing a 5N NaCl solution.
Before diving into the procedure for preparing a 5N NaCl solution, it is important to understand what concentration means. Concentration refers to the amount of solute dissolved in a solvent. It is typically expressed as moles per liter (mol/L) or molarity. The concentration can also be expressed in other units, such as Normality (N), which is the number of equivalents of solute per liter of solution.
Definition of 5N Solution
A 5N solution of NaCl refers to a solution containing five equivalents of NaCl per liter of solution. An equivalent is a measure of the number of reactive species in a substance. In the case of NaCl, one mole of NaCl is equivalent to two reactive species, one mole of Na+ and one mole of Cl-. Therefore, a 5N solution of NaCl contains ten moles of NaCl in one liter of solution.
To prepare a 5N NaCl solution, the following materials are required:
- NaCl powder or crystals
- Deionized water
- A volumetric flask (one liter)
- Weighing balance
- Graduated cylinder
- Stirring rod
The procedure for preparing a 5N NaCl solution can be broken down into four main steps:
- Preparation of solution
- Checking concentration
- Adjusting concentration
- Storing solution
Step 1: Preparation of Solution
To prepare the solution, weigh 292.2 grams of NaCl and dissolve it in a small quantity of deionized water. Transfer the solution to a one-liter volumetric flask, and add deionized water until the flask is almost full. Stir the solution thoroughly to ensure the NaCl is completely dissolved. Finally, fill the flask to the one-liter mark with deionized water.
Step 2: Checking Concentration
To check the concentration of the solution, use a titration process. Take a sample of the solution and titrate it with a standardized solution of AgNO3. The endpoint of the titration is reached when all the Cl- ions in the NaCl solution have reacted with AgNO3 to form a white precipitate of AgCl. The concentration of the NaCl solution can be calculated by using the formula: N = (V1 x N1) / V2, where V1 is the volume of AgNO3 solution used, N1 is the concentration of AgNO3, and V2 is the volume of NaCl solution used.
Step 3: Adjusting Concentration
If the concentration of the solution is not 5N, it can be adjusted by adding more NaCl or water to the solution. If the concentration is too low, dissolve more NaCl in deionized water and add it to the solution in small quantities, checking the concentration after each addition until the desired 5N concentration is achieved. If the concentration is too high, add more deionized water to the solution until the desired concentration is achieved.
Step 4: Storing Solution
The 5N NaCl solution can be stored in an airtight container in a cool, dry place. It is important to label the container with the contents, concentration, date of preparation, and any other relevant information.
When working with chemicals, it is important to take safety precautions to prevent accidents. Always wear appropriate personal protective equipment, such as gloves and goggles. Handle chemicals with care and avoid inhaling fumes. Dispose of any waste materials properly and follow all safety guidelines.
Preparation of a 5N NaCl solution is a basic but important procedure in many chemical and biological experiments. By following the steps outlined in this article, you can prepare a 5N NaCl solution with ease and accuracy. With proper safety precautions and storage, you can use this solution for a wide range of experiments.
- Chang, R., & Goldsby, K. A. (2013). Chemistry (12th ed.). New York: McGraw-Hill.
- Harris, D. C. (2010). Quantitative chemical analysis (8th ed.). New York: W. H. Freeman and Company.