Chapter 11, Problem 28PS

When water is placed in a buret it forms a concave meniscus at the surface. In contrast, mercury (in a manometer for example) forms a convex meniscus (Figure 11.17). Explain why this phenomenon occurs, and why the two liquids give different results. Predict the meniscus shape if the buret is filled with ethylene glycol (HOCH₂CH₂OH).

Meniscus

Water in glass tubes (right) is attracted to the polar ‒OH groups on the surface of glass and so water forms a downward facing or concave meniscus. Mercury, however, is not attracted to the glass surface, and so forms a convex meniscus (left).