Okay, that’s enough with the quotes. Let us return to The List from last week. Sadly all the obvious properties of water have been used, so it’s going to get very science-y.
9. Water has a high tensile strength.
Tensile strength is a measure of how well a material can withstand stretching. It’s difficult to imagine water being ‘stretched’, but it has been found that columns of water do not easily break or pull apart. Along with property number eight of adhesiveness and cohesiveness, continuous columns of water can be pulled all the way to the top of trees to supply the cells there with food.
10. Water is a common metabolite.
A metabolite is a substance that takes part in biochemical reactions in cells. Water is involved in almost all of these biochemical reactions – one example is photosynthesis, the process that plants use to make food from sunlight.
11. Water is the universal solvent.
A solvent is a substance, usually a liquid, that dissolves another substance (called the solute) to produce a solution. Water is polar (see property number eight), allowing it to dissolve more substances than any other common solvent. This is a reason why your body is 60-70% water, because other chemicals can dissolve in it.
12. Water combines with many organic molecules to form hydrated molecules.
In cells, most organic molecules react with water molecules to form new hydrated molecules. The supplementary water molecules contribute to their physical and chemical properties, allowing a greater variety of substances to exist. In fact, you will have heard of the term ‘carbohydrate’, a type of molecule found in foods such as bread and rice that form a major part of a balanced diet.
13. Water has a high specific heat capacity.
Specific heat capacity is a measure of how much energy is required to raise the temperature of a substance. Water has a high specific heat capacity, so it must gain or lose a lot of energy to change temperature. Oil has a lower specific heat capacity, so it is quicker to heat up oil than it is to heat up water. This is particularly important on both small and large scales: on a small scale, the internal environment of an organism is able to resist temperature change; on a large scale, aquatic habitats have relatively stable temperatures, as water can ‘absorb’ any temperature changes.
14. Water has a high latent heat of vaporisation.
Latent heat of vaporisation is a measure of how much energy is required for a substance to evaporate. Water has a high latent heat of vaporisation, so water takes in a lot of energy from any surface it evaporates from. This property is responsible for cooling mechanisms such as sweating in mammals.
15. Water has a high latent heat of fusion.
Hmm… sounds like the one above (you’re not wrong). Latent heat of fusion refers to freezing instead of evaporation. Water has a high latent heat of fusion, which means that water must lose a lot of energy in order to freeze. This enables the possibility of water reaching temperatures far below 0 °C before it actually freezes. In addition, water in living cells and aquatic environments are slow to freeze at low temperatures.
16.Water is neutral in pH.
pH measures the acidity of a substance. Water is neither acidic nor basic (the opposite), which is perfect for our health. If water were only slightly higher or lower in pH, there would be adverse health effects on most living organisms in the world. In addition, pH is a factor in determining the solubility of substances in water (how well they dissolve). Changes in pH can create eutrophic environments, a disastrous condition where oxygen concentration is too low in a body of water, so plants thrive but animals die.
17. Water is amphoretic.
Amphoretism is the special property of being able to react as both an acid and a base. This is due to the dissociation of water into H+ and OH– ions (I’m aware that this might mean nothing to you). It’s still very important though, as it’s one of the reasons why water is in most biochemical reactions, and it helps maintain pH inside organisms.
18. Water conducts electricity when it contains dissolved ions.
Some substances do not conduct electricity as a solid, but conduct when dissolved in water to form ionic solutions (for instance saltwater). Ionic solutions are found in bodily fluids and help transmit electrical impulses for the functioning of the heart, brain and muscles.
With these eighteen properties, the biological significance of water covers a vast scope; from the microscopic biochemical reactions inside living cells, to the macroscopic ocean environments; from the transport of water inside plants to the maintenance of stable conditions inside mammals. There were more properties than you were expecting, right? So next time you hold a drink of water in your hand, think about how water seems to be perfectly designed to allow our survival…
…or actually, you could just, you know, drink it.