Volumetric flasks are employed to measure precise volumes of liquids to make standard solutions or weigh for density calibrations. The volumetric flasks aid in quantitative laboratory work. Made of low expansion coefficient and chemically resistant borosilicate; our volumetric flask is an optimum combination of resistance and readability. Volumetric flasks can be capped to prevent material in the flask from evaporating as well as to maintain the material’s purity.
The proper procedure of filling and using the volumetric flask is as follows:
- Transfer the liquid to be measured into the flask with the help of a pipette The instrument used for liquid transfer should supply a steady stream against the wall, about a centimeter above the calibration line. One should not splash the liquid. The tip of the pipette or a burette may touch the wall of the flask.
- After reaching the level below the calibration line, cap the container and let the liquid drain from the walls of the flask.
- Fill the flask as required. If the calibration line is crossed, a pasture pipette can be used to draw out the excess fluid. Make sure that the surface tension in the tip of the pipette is sufficient to draw out the fluid. Once completed, cap the flask.
Method for the gravimetric purpose:
- Properly clean and dry the flask.
- Using the physical balance weigh the flask, its cap, and any other materials that may interfere with the final weighing.
- Note the liquid’s temperature and the room’s barometric pressure and humidity, if accurate readings are required.
- Carefully transfer the liquid to be measured into the flask using a pipette or a burette.
- When the level is just below the calibration line, put the cap on the container and let the liquid drain from the walls of the container.
- Weigh the filled flask.
- If Step 3 was performed, repeat it to verify the readings.
- Deduct the empty flask weight from the filled flask weight.
Method for making a definite solution:
- Properly clean the flask and dry it.
- Transfer the pre-calculated concentrated liquid into the flask using a pipette or a burette. Do not splash.
- Add distilled water to the flask up to the calibration line using a pipette, a burette, or any other device that can supply a steady stream against the wall about a centimeter above the calibration line trying to rinse any of the concentrated liquid remaining on the flask’s neck. Cap the container after reaching up to the calibration line and let the liquid drain from the walls of the container.
- Complete the filling process using step 3 again. Try not to cross the calibration line because any excess liquid may dilute the required concentration.
To empty the volumetric flask, follow the following procedure:
Incline the flask slowly to provide a steady stream of liquid from the spout. Continue inclining until the flask is vertical and hold it for half a minute to empty the flask fully. Wipe the drop at the tip of the flask with the wall of the receiving container. Make sure not to remove the flask in a vertical position.