To accurately measure the final volume of a solution in a burette, it is important that you read of the measurement in the lower meniscus like for water and for substances like mercury you read it on the upper meniscus. This is the standard way of reading volumes in laboratory apparatus. Also, it should be that the apparatus standing vertically in a plain surface.
The precision to measure a volume in a burette will depend on the shape of the meniscus that forms the liquid. In the case of a concave meniscus, its reading will be made at the lowest height of the liquid surface. This point should touch the upper edge in the division of the burette scale. In the case of a convex meniscus, its reading will be made at the highest height of the liquid surface. This point should touch the bottom edge in the burette scale division.
Explanation:
The accuracy when reading the correct volume in a burette depends on the type of meniscus. If the molecules of a liquid have a greater attraction to the glass wall, the meniscus will have a concave shape, for example, aqueous solutions. A requirement to measure exactly is the adjustment of the meniscus. As stated before, if the meniscus shape is concave, the volume will be read at the lowest height of the liquid surface. If the meniscus is convex, the volume will be taken at the highest height of the liquid surface. Convex menisci are formed by substances such as mercury.
