0.1 M Sodium Thiosulfate Preparation
Sodium thiosulfate is a versatile chemical compound with various applications in industries such as photography, medicine, and water treatment. In laboratory settings, sodium thiosulfate solutions are commonly used as a titrant in iodometric titrations to determine the concentration of oxidizing agents. Here's a step-by-step guide on how to prepare a 0.1 M sodium thiosulfate solution.
Materials Needed
- Sodium thiosulfate (Na2S2O3) crystals
- Distilled water
- A 100 mL or 250 mL volumetric flask
- A pipette or measuring cylinder
- A balance or scale
Preparation
Step 1: Calculate the Amount of Sodium Thiosulfate Required
To prepare a 0.1 M sodium thiosulfate solution, you need to calculate the amount of sodium thiosulfate required. The molar mass of sodium thiosulfate is 158.11 g/mol.
For a 100 mL solution:
Molarity (M) = 0.1 mol/L
Volume (V) = 100 mL = 0.1 L
Number of moles (n) = M x V = 0.1 mol/L x 0.1 L = 0.01 mol
Mass (m) = n x molar mass = 0.01 mol x 158.11 g/mol = 1.5811 g
For a 250 mL solution:
Molarity (M) = 0.1 mol/L
Volume (V) = 250 mL = 0.25 L
Number of moles (n) = M x V = 0.1 mol/L x 0.25 L = 0.025 mol
Mass (m) = n x molar mass = 0.025 mol x 158.11 g/mol = 3.95275 g
Step 2: Weigh the Sodium Thiosulfate
Using a balance or scale, accurately weigh the calculated amount of sodium thiosulfate.
Step 3: Transfer the Sodium Thiosulfate to the Volumetric Flask
Transfer the weighed sodium thiosulfate to a clean and dry 100 mL or 250 mL volumetric flask.
Step 4: Add Distilled Water
Add distilled water to the volumetric flask until the solution reaches the calibration mark. Make sure to mix the solution thoroughly to dissolve the sodium thiosulfate completely.
Step 5: Mix and Label the Solution
Mix the solution well and label it as 0.1 M sodium thiosulfate solution.
Tips and Precautions
- Always handle sodium thiosulfate with care, as it can cause skin and eye irritation.
- Wear protective gloves and eyewear when preparing the solution.
- Use distilled water to prevent contamination and ensure the accuracy of the solution.
- Store the prepared solution in a cool, dry place, away from direct sunlight.
By following these steps, you can prepare a 0.1 M sodium thiosulfate solution accurately and safely. This solution is ready to use for iodometric titrations and other applications.
