A volumetric flask is a laboratory glassware commonly used for precise measurements of liquid volumes. Let’s delve into its functions and applications:

1. Preparation of Standard Solutions:

   • Volumetric flasks are essential for creating standard solutions. These solutions have precisely known concentrations and are used as references for analytical measurements.
   • When preparing a standard solution, the flask is filled to a line etched on the neck, ensuring a specified volume (usually calibrated to contain, TC).
   • These solutions serve as benchmarks for titrations, spectrophotometry, and other quantitative analyses.

2. Dilution of Samples:

   • Before taking aliquots with a pipette, samples often need to be diluted to a fixed volume.
   • Volumetric flasks allow precise dilution by adding a known volume of sample and then filling up to the calibration mark.
   • Some flasks are also calibrated on a to-deliver (TD) basis, distinguished by two reference lines on the neck. Filling to the upper line ensures delivery of the stated volume.

3. Quantitative Transfer of Liquid:

   • When transferring liquids to a volumetric flask, follow these steps:
     1. Insert a funnel into the flask’s neck.
     2. Direct the liquid flow from the beaker into the funnel using a stirring rod.
     3. Tip off the last drop of liquid from the beaker’s spout.
     4. Rinse both the stirring rod and the beaker interior with distilled water, transferring the washings to the flask.
     5. Repeat the rinsing process at least twice.
   • This ensures accurate transfer and minimizes loss of liquid.

4. Diluting to the Mark:

   • After transferring the solute, follow these steps:
     1. Fill the flask halfway and swirl to hasten dissolution.
     2. Add more solvent and mix well.
     3. Bring the liquid level almost to the mark and allow drainage.
     4. Use a medicine dropper for any final additions of solvent.
     5. Firmly stopper the flask and invert it to ensure thorough mixing.
     6. Transfer the contents to a storage bottle.

5. Important Notes:

   • If the liquid level accidentally exceeds the calibration mark, correct for the excess volume.
   • Use a self-stick label to mark the location of the meniscus.