Measuring a liquid volume
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When measuring a liquid volume, it's essential to read the meniscus correctly. Consider the picture above. It shows the meniscus of mercury is convex in shape while water forms a concave meniscus. The concave meniscus shown by water is the most common meniscus and it should be read at the bottom, mid-part of the curve at eye level.
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In carrying out a titration, which pieces of equipment will require students to read the meniscus correctly?
A burette is the obvious piece of glasswear requiring students to read the meniscus for an initial reading and a final reading. Correctly reading the meniscus is also essential when using a volumetric pipette in order to accurately measure the amount of solution placed in the flask.
The scale can be read to an accuracy of half a division of the marked graduated scale, eg 0.05 cm3. Students will also need to appreciate the upside-down nature of the scale compared with their previous experience of reading graduated scales. Then they will need plenty of practice. Online simulations can be helpful in giving further practice in noting the readings of a burette. For example, try the following simulation by clicking on this image.
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How were your readings?