0.1 N AgNO3 Standardisation
Introduction
Silver nitrate (AgNO3) is a strong oxidizing agent widely used in various fields, including analytical chemistry, ecology, and medicine. In analytical chemistry, AgNO3 is often used as a standard solution to determine the concentration of chloride ions in a sample. To ensure accurate results, it is essential to standardize the AgNO3 solution. This article will guide you through the process of standardizing a 0.1 N AgNO3 solution.
Theory
The reaction between AgNO3 and NaCl is as follows:
AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq)
The reaction is quantitative, meaning that one mole of AgNO3 reacts with one mole of NaCl to form one mole of AgCl. By measuring the amount of NaCl required to precipitate AgCl, the concentration of AgNO3 can be determined.
Materials
- 0.1 N AgNO3 solution
- Sodium chloride (NaCl) crystals
- Distilled water
- Burette or pipette
- Conical flask
- Filter paper
- Volumetric flask
Procedure
Preparation of NaCl Solution
Weigh accurately about 0.5 g of NaCl crystals into a 100 mL volumetric flask. Add about 50 mL of distilled water and stir until the NaCl is completely dissolved. Then, add more distilled water to the mark and mix well.
Titration
- Transfer 20.00 mL of the 0.1 N AgNO3 solution into a conical flask.
- Add a few drops of indicator (e.g., potassium chromate) to the AgNO3 solution.
- Titrate the AgNO3 solution with the NaCl solution until a permanent white precipitate of AgCl is formed.
- Record the volume of NaCl solution required to reach the endpoint.
- Repeat the titration at least three times and calculate the average volume of NaCl solution required.
Calculation
Let the average volume of NaCl solution required be x mL. Since the reaction is quantitative, we can set up the following equation:
1 L AgNO3 × (x mL / 1000 mL) = 1 L NaCl × (20.00 mL / 1000 mL)
Simplify the equation and solve for the concentration of AgNO3:
[AgNO3] = (x mL / 20.00 mL) × (1 mol / 1 L) × (1 L / 1000 mL)
Result and Discussion
The concentration of the standardized 0.1 N AgNO3 solution can be calculated using the equation above. The result should be close to the theoretical value of 0.1 N. Any significant deviation may indicate errors in the titration process or impurities in the AgNO3 solution.
Conclusion
In this article, we have discussed the standardization of a 0.1 N AgNO3 solution using NaCl as the primary standard. The procedure involves titrating the AgNO3 solution with a NaCl solution until a permanent white precipitate of AgCl is formed. By calculating the concentration of the standardized AgNO3 solution, we can ensure accurate results in subsequent analytical procedures.
