How do the unique chemical and physical properties of water make life on earth possible?

Question

Lydia Adams · Accepted Answer

Water keeps chemistry working, nutrients moving, temperatures stable, bodies of water from not completely freezing through.

This 4 min youtube video by RicochetScience does an amazing job explaining and visualizing the unique properties of water and how it helps life exist:

So instead of paraphrasing the video, let's provoke some creative thoughts by thinking through what would happen to living beings and life on earth if the unique properties of water were flipped around to their opposite extremes:

Hey, it's OPPOSITE DAY for Water:

Water is NOT a universal solvent: substances that would usually dissolve in water no longer do; they become like sand in water instead. Almost all chemical reactions necessary for life (which would usually occur when reactants dissolve and mix together) stop or drastically slow down.
Water has LOW cohesion and adhesion: waste and nutrients are no longer transportable around an organism's circulatory system (i.e. your bloodstream) as carried by water. Plants would quickly droop and die because capillary action is no longer possible, taking away their ability to carry water and nutrients up against gravity from the soil. Insects that usually walk on water would immediately sink to the bottom and drown.
Water has LOW heat capacity: instead of moderating temperature levels to a pleasant, livable range, water’s temperature would rise and fall more rapidly and to greater extremes (like aluminum, which has low heat capacity) causing temperatures around the world to swing from extreme from extreme as the sun rises and falls. Human bodies, consisting of 55-75% water, would also face the same extreme swings.
Ice (solid water) is MORE dense than liquid water: If everything above wasn’t bad enough, if water in the solid state was more dense than in the liquid state, ice would no longer float. Without floating ice being a protective layer that insulates all the liquid water below, water would turn into ice from the bottom up and cause all water-based life to freeze and die.

This is not a comprehensive listing of everything that would happen; it's just a fun and usefully absurd thought experiment to challenge your understanding of exactly how and why water is so important to life.

Got some examples of your own? Please share!

Jeremiah Allen · Answer

undefined The unique chemical and physical properties of water make life on Earth possible through several key characteristics:

1. High Heat Capacity: Water can absorb and release a large amount of heat with minimal temperature change. This property helps regulate temperature on Earth and within living organisms, providing a stable environment.

2. High Heat of Vaporization: Water requires a large amount of heat to change from a liquid to a gas. This property enables organisms to use sweating and transpiration to cool down, which is crucial for thermoregulation in many species.

3. Universal Solvent: Water is an excellent solvent due to its polarity, allowing it to dissolve many substances. This property is essential for transporting nutrients, waste, and other substances within organisms.

4. Cohesion and Adhesion: Water molecules are attracted to each other (cohesion) and other substances (adhesion). These properties enable water to move against gravity in plants (capillary action), contributing to the transport of water and nutrients.

5. High Surface Tension: Water has a high surface tension, allowing small organisms like insects to walk on its surface. It also prevents water from evaporating too quickly, maintaining a stable environment for aquatic life.

6. High Boiling and Melting Points: Water has a relatively high boiling and melting point for its molecular size, which allows it to exist in three phases (solid, liquid, and gas) at temperatures found on Earth. This property enables water to support life in various environments, including extreme conditions.

Overall, the unique chemical and physical properties of water contribute to its essential role in sustaining life on Earth.