This is a highly accurate 250 mL borosilicate glass volumetric flask with a single ground-in graduation mark and glass ST No. 16 stopper. It meets ASTM E-288 Class A Specifications and USP Standards for Volumetric Glassware.
A volumetric flask is used to prepare a solution of fixed volume very accurately. Read how to use a volumetric flask under the "More Details" tab.
Features...
- Machine-blown body.
- Heavy-beaded, heavy-tubing neck.
- Tooled for Standard Taper (ST) stoppers.
- The graduation line is sharp and permanent.
- Large, white, block-letters allow the labeling to be easily read.
- Large marking square.
Specifications...
- Capacity: 250 mL
- Tolerance: ± 0.12 mL
- ST Stopper: No. 16
- Approx. O.D. x Height: 78 x 239 mm
How to use volumetric flasks.
Many different varieties of laboratory glassware can be used to prepare a chemical solution. Where accuracy and precision are most important, a Volumetric Flask is the optimal choice.
The flasks are made from borosilicate glass, the type used widely for its chemical and thermal resistance and optical quality.
We have five sizes of volumetric flasks to choose from: 50, 100, 250, 500 and 1000 milliliters and they feature a single etched line or graduation to denote the fill-to-line at the chosen volume. Each size flask is specifically made for preparing solutions that correspond to its nominal value. For example, a 250 ml volumetric flask is the appropriate choice only when preparing a solution with a total volume of 250 ml.
Procedure...
- Begin by selecting the appropriately sized flask for your procedure.
- Calculate and measure the mass of solid material needed to prepare the desired solution.
- Next, transfer the material into the flask, using a funnel to assure no material is lost during transfer.
- Rinse the sides of the funnel with your solvent (e.g. water for aqueous solutions) down into the flask to capture any residual material adhering to the funnel.
- Next, fill the flask about halfway with your solvent, cap the flask and swirl to dissolve the solid material into solution.
- Once the solid material has been dissolved, fill the flask with your solvent almost to the etched line.
- Pause and let any liquid drain down from the sides of the flask.
- Next, use a medicine dropper to carefully add enough solvent to raise the base of the meniscus of the solution to the level of the etched line.
- Finally, cap, mix, swirl and store your prepared solution until ready to use.
