How many milliliters does a 250 mL volumetric flask hold?

A two hundred and fifty milliliter volumetric flask holds two hundred and fifty milliliters of liquid when filled to the calibration mark.

A volumetric flask is made to measure one exact volume, so when you pour liquid in until the bottom of the little line on the neck touches the surface, you have two hundred and fifty milliliters. Think of the flask like a picture frame with a single size; it is not for estimating different amounts, it is for getting that one amount right. The neck is narrow so a small change in height equals a small change in volume, which helps you fill it precisely. Chemists and students use it for making solutions because it gives the same amount every time when used correctly.

A common mistake is filling past the calibration mark and assuming you can pour out until it looks level, which makes the volume too high, so always bring the meniscus down to the mark. Another mistake is reading the mark from above or below eye level, which changes how the curved meniscus appears, so crouch or raise your head so your eye is exactly level with the mark. Some people think rinsing the flask is optional, but residue changes concentration, so rinse the inside with the solution or solvent before final fill.

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Using a Two Hundred and Fifty Milliliter Volumetric Flask

1. Fill to bottom of calibration line
2. Volumetric flask measures one exact volume
3. Use narrow neck for precise filling
4. Small height change alters volume significantly
5. Use for making consistent solutions

Common Volumetric Flask Mistakes

1. Filling past the calibration mark
2. Reading meniscus from wrong eye level
3. Skipping rinsing before final fill

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