Question

Is the surface tension of water unusually high or low?

Short answer

Water has an unusually high surface tension compared to other liquids.

Step-by-step solution

Understanding Surface Tension

Surface tension is the energy required to increase the surface area of a liquid by a unit amount. It is usually measured in newtons per meter (N/m). For water at room temperature, the surface tension is about 0.0728 N/m.

Compare with Other Liquids

Other common liquids have lower surface tensions compared to water. For example, ethyl alcohol has a surface tension of around 0.022 N/m, significantly lower than that of water. This indicates that water has a relatively high surface tension.

Effect of Surface Tension

The high surface tension of water allows for phenomena such as water droplets forming beads on surfaces and certain small insects, like the water strider, being able to walk on water without sinking.

Conclusion

Based on its comparison with other liquids and its physical properties, water's surface tension is considered unusually high. This high surface tension is due to strong hydrogen bonding between water molecules.

Key concepts

Hydrogen Bonding

In the world of chemistry, hydrogen bonding stands out as a powerful force. It's what gives water its unique traits. But what exactly is hydrogen bonding? It's a type of attraction between molecules, not as strong as covalent or ionic bonds, but still significant.
Water molecules, labeled chemically as H oh, engage in hydrogen bonding because of their shape and charge distribution. The oxygen atom is more electronegative, pulling the electron cloud closer to itself and away from the hydrogen atoms. This creates a partial negative charge around the oxygen and a partial positive charge at the hydrogens.
Thanks to this arrangement, water molecules are naturally attracted to each other, like tiny magnets. This attraction is what we call hydrogen bonding. It contributes to many of water's special features like high surface tension, boiling point, and its role as a universal solvent.

Properties of Water

Water is a truly remarkable liquid, showcasing characteristics that may not be obvious at first glance. Its properties are largely influenced by hydrogen bonding. Here are some key properties of water:

• High Surface Tension: Water has a surface tension of 0.0728 N/m at room temperature, one of the highest among common liquids. This allows water to form droplets and enables insects like water striders to glide on its surface.
• Cohesion: The hydrogen bonds holding water molecules together result in strong cohesion. This is why water beads up on surfaces and can rise in narrow tubes (capillary action).
• Adhesion: Water also sticks well to other materials. This property contributes to capillary action and is vital for processes like plant water transport.
• High Boiling Point: Compared to other similar-sized molecules, water has a high boiling point due to the strength of the hydrogen bonds.
• Universal Solvent: Water dissolves many substances, allowing it to carry nutrients and waste products in living organisms. This characteristic supports countless biochemical reactions.

Liquid Comparison

When comparing liquids, water often stands out due to its unique properties influenced by hydrogen bonding. Here’s how water compares with other common liquids:

Surface Tension: Water's surface tension is significantly higher than many other liquids. For example, ethyl alcohol has a surface tension of about 0.022 N/m, while water's is 0.0728 N/m. This is primarily due to strong hydrogen bonds in water, which are weaker or absent in many other liquids.

Boiling and Freezing Points: Water has relatively high boiling and freezing points compared to other similar molecules, like methane (CH extsubscript{4}) or ammonia (NH extsubscript{3}). This is a result of the extensive network of hydrogen bonding in water.

Cohesion and Adhesion: Unlike most other liquids, water has a strong tendency to cling to itself (cohesion) and to other substances (adhesion). This is why it can "climb" surfaces and move against gravity in plants.

These unique characteristics make water essential for life as we know it and highlight how distinct it is when lining it up with other liquids.