Water is without a doubt one of the most important elements for us, to the point that every form of life known so far would not have been possible without its existence. It is part of each and every cell of our body, and we must drink it often in order to survive.

The importance of water is paramount, but beyond that the truth is that this element has different properties of interest at the scientific level. That is why throughout this article we are going to see a brief explanation of some of the main physical and chemical properties of water .

Physical and chemical properties of water

These are some of the properties of this element, some of them highly known by most people and others more technical and less taken into account.

1. It is colorless

Although when we see the sea or a river it may seem to us that the water may have a bluish greenish or sometimes brownish colour, this is due to the way in which it reflects the light and because absorbs short wavelengths more easily (which makes it easier for our eyes to appear in bluish tones). However, we cannot perceive any colour in it (unless it is mixed with another substance), being transparent to our sight.

2. No taste or smell

Water is a substance that, unlike others, does not possess a specific taste or smell by itself. If water tastes like something to us it is because it has been adulterated in some way (for example by adding flavours) or because on reaching us it has dragged particles of other elements (for example fruits or other foods, minerals, lime, plastic or contaminants).

3. Found in nature in all three states

There are many substances that are complicated to find in nature beyond a particular state of matter. However, in the case of water we can easily observe it in any of the states: liquid water from seas, rivers and rain, in gaseous form can be observed as water vapor and in solid form can be found as ice and snow.

4. It has a fixed transformation temperature

Although water can be mixed with other substances, the truth is that at a physical level we can see how this element always evaporates or freezes at the same temperature , with a freezing point at 0ºC and a boiling point at 100ºC.

5. Compound and non-element

Although since ancient times water has been thought of as one of the basic elements, the truth is that as its chemical formula, H2O, indicates, we are not dealing with an element in itself but with a compound in which each molecule is made up of two hydrogen atoms joined to an oxygen atom.

6. It is a solvent

Perhaps the word solvent is used at a popular level for other types of substances, but the truth is that at a chemical level water does act as such. The fact is that many substances dissolve in contact with H2O , and water is capable of changing its structure and properties.

In fact, it is an almost universal solvent of polar substances (i.e. substances whose molecules have a positive pole at one end and a negative pole at the other), such as alcohol or salts. Apart from chemical reactions in the laboratory, this property is indispensable for explaining, for example, the functioning of the living cells of our organism.

7. It has a neutral electrical charge

The atoms of a water molecule have a neutral electrical charge, although this does not mean that its components are not charged, but that it is usually balanced. Usually each molecule consists of ten or so protons and electrons, in which the electrons are concentrated near the oxygen. Thus, around oxygen the electrical charge tends to be somewhat more negative , while near hydrogen it is more positive.

8. Stable density

Just as freezing and boiling points are usually fixed, water is also characterised by maintaining a very stable density regardless of its environmental situation. Pure water without any other component (i.e. distilled) has a density of 1 kg/l.

However, normally when it is in a liquid state at a temperature of around 20ºC it has a density of 0.997-0.998 kg/l . In the case of ice, its density is usually 0.917 kg/l.

9. Difficult to compress

Compressing a certain volume of water is highly complex (although not impossible), as this substance has a high level of cohesion (i.e. its molecules have a high capacity to remain united with each other due to the strong bond they make).

10. Adheres

The water is wet. This phrase, although it may seem obvious and even ridiculous, is telling us about another of the physical properties of the liquid element: the ability to adhere to other surfaces and materials .

11. Low electrical conductivity

We have probably heard of someone who has been electrocuted to death or suffered a domestic accident when water comes into contact with an electrical element. As most people know, these kinds of accidents are very real and dangerous.

However, it must be taken into account that the person responsible is not really the water, but the different salts and other components that it carries with it . In fact, distilled or pure water is not an electricity conductor but an insulator, since it does not have free electrons that can conduct it.

However, it is important to note that we are talking about distilled water in which there is nothing but water molecules: the water we drink, shower and bathe with and that we find in rivers and seas does conduct electricity because it contains a large amount of minerals and other components with conductive potential.

12. Relatively neutral pH

Another characteristic of water is that it is generally and on average neutral or almost neutral, with a pH between 6.5 and 8.5 (a totally neutral pH would be 7). This implies that generally water can be slightly acidic or slightly basic , but unless its degree of acidity is manipulated or it is mixed with other substances, pure water molecules are usually practically neutral.

13. Participates in multiple chemical reactions

Another aspect to take into account of water is its high level of interaction with other elements, so that it produces different chemical reactions and becomes part of different processes or substances.

For example, as we have already seen, it is capable of dissolving polar substances, as well as reacting with basic oxides and acids to form compounds such as calcium hydroxide or sulphuric acid. Also can generate various reactions on different types of metals , and participates in processes such as oxidation or the creation of hydrates.

14. High surface tension

This property refers to the force needed to overcome the force of attraction between water molecules at surface level .

Its high value (in the case of water has a value of 72.8 dyne/cm) makes it generally when we are in front of a surface of calm water this tent to remain stable, something that makes it difficult to break its form but applies a considerable force. That is why leaves or other objects usually float on top of it without generating an excessive alteration in the shape of the surface.

15. Regulates the temperature

Another interesting and well-known property of water is its ability to regulate temperature. This is because water is able to retain heat, which causes it to cool down more slowly than other substances. It also takes longer to heat up. An example of this is the effect of the sea on the temperature of the coast, which is generally more moderate than inland.

Bibliographic references:

  • Marín Galvín, R. (2010). Physical, chemical and biological characteristics of waters. School of Industrial Organization. [Online]. Available at: https://www.eoi.es/es/savia/publicaciones/19900/caracteristicas-fisicas-quimicas-y-biologicas-de-las-aguas.
  • Marín Galvín, R.; Rodríguez Mellado, J.M. (1999). Water physicochemistry. Editorial Díaz de Santos.
  • Félez Santafé, M. (2009). Current status of biological treatment. Explanation of the methods and their foundations. Escola d$0027Enginyeria de Barcelona- E.T. Industrial, especialitat en Química Industrial. Polytechnic University of Catalonia [Online]. Available at: http://hdl.handle.net/2099.1/6263.