CONCEPTS

What are water states?

We explain what are the states of water, the characteristics of each and how the change between one and the other occurs.

  1. What are water states?

We all know what water is , and we know its three presentations, known as the physical states of water. This is: liquid (water), solid (ice) and gas (steam), the three ways in which water can be found in nature, without changing its chemical composition at all , which is always what denotes its formula H 2 O: hydrogen and oxygen.

That the water is present in any of these three physical states , depends on the pressure around it and the temperature at which it is , that is, on the environmental conditions. Therefore, by manipulating these conditions it is possible to convert liquid water into solid or gaseous, or vice versa.

Given the importance of water for life and its abundant presence on the planet, its physical states are used as a reference for many measurement systems and thus allow comparisons with other materials and substances.

  1. Water properties

water states surface tension properties
Insects and spiders can move along the surface of the water due to their surface tension.

Water is an odorless, colorless, tasteless substance with a neutral pH (7, neither acid nor basic). It is composed of two atoms of hydrogen and one of oxygen in each molecule.

Its particles have an enormous force of cohesion, which holds them together, so that it has an important surface tension (some insects take advantage of it to “walk” on water) and it takes a lot of energy to alter their physical states.

Water is known as the ” universal solvent “, since it can dissolve many more substances than in any other liquid . In addition, it is a fundamental compound for life, abundantly present in all organisms . Water covers two thirds of the total surface of our planet .

  1. Liquid state

cascade liquid water states
In a liquid state the water is fluid and flexible.

The state that we associate most with water is the liquid , its state of greatest density and incomprehensibility , and also the most abundant on our planet.

In their liquid state, the water particles are together, although not too much. Therefore, it presents a flexibility and fluidity typical of liquids, and instead losing its own shape, to adopt that of the container that contains it.

Thus, liquid water requires certain conditions of energy ( heat ) or pressure , which in our ordinary atmosphere is between 0 and 100 ° C . However, it is possible to exceed its boiling point , if it is subjected to higher pressures (superheated water), being able to reach the critical temperature of 374 ° C, temperature limit at which gases can be liquefied.

Liquid water is ordinarily found in seas, lakes, rivers and underground deposits , but also contained in the bodies of living beings .

  1. Solid state

ice solid water states
The ice that covers the lakes is less dense than the water.

The solid state of water is commonly known as ice , and is reached by lowering its temperature to 0 ° C or lower . A curiosity of frozen water is that it gains volume compared to its liquid state. In other words, ice has a lower density than water (which is why the first floats).

The ice is hard, fragile and transparent in appearance, throwing white and blue, depending on its purity and the thickness of its layers. Under certain conditions it can be temporarily maintained in a semi-solid state, known as snow.

Solid water can ordinarily be found in glaciers, at the top of the mountains, on frozen soils (permafrost) and on the outer planets of the Solar System, as well as inside our food freezer.

  1. Gaseous state

gaseous steam water states
When exhaling on a cold day we can see the water in a gaseous state.

The gaseous state of water is known as steam or water vapor, and is a usual component of our atmosphere , present even in every exhalation we give. In conditions of low pressure or high temperature, water evaporates and tends to rise, since steam is less dense than air .

The change to the gaseous state occurs at 100 ° C , as long as one is at sea level (1 atmosphere). The gaseous water makes up the clouds we see in the sky, is in the air we breathe (especially in our exhalations) and in the mist that appears on cold and damp days. We can also see it if we put a pot of water to boil.

  1. changes of water’s state

As we have seen in some of the previous cases, water can change from one state to another, simply by varying its temperature conditions. This can be done in one direction or another, and each different process will be given its proper name, as follows:

  • Evaporation . Liquid to gaseous transformation, increasing the water temperature to 100 ° C. It is what happens with the boiling water, hence its characteristic bubbling.
  • Condensing . Reverse process: transformation of gas to liquid, due to heat loss. This is what happens with water vapor when it condenses on the bathroom mirror: the surface of the mirror is colder and the vapor that perches on it becomes liquid.
  • Freezing . Transformation of liquid to solid, lowering the water temperature below 0 ° C. Water solidifies, producing ice, just like in our freezers or at the peak of the mountains .
  • Melting . Reverse process: transformation of solid water to liquid, adding heat to the ice. This process is very everyday and we can see it when we add ice to our drinks.
  • Sublimation . It is the process of transformation from gaseous to solid, in this case from water vapor, to ice or snow directly. For this to happen, very specific temperature and pressure conditions are required, which is why this phenomenon occurs at the top of the mountains, for example, or in droughts in Antarctica, where water is impossible.
  • Inverse sublimation . Reverse process: transformation of a solid directly to gaseous, that is, from steamed ice. We can witness it in very dry environments, such as thepolar tundra itself, or in the mountainous summit, where as solar radiation increases, much of the ice is sublimated directly to gas, without going through a liquid stage.
  1. Hydrological cycle

The hydrological cycle or water cycle is the circuit of transformations that water experiences on our planet, going through its three states , gaining and losing temperature and moving around.

It is a complex circuit that involves the atmosphere, oceans , rivers and lakes, and ice deposits in the mountains or at the poles. Thanks to it, the planet’s temperature remains stable , dry regions are hydrated and rainy ones are dried, maintaining a climatic balance that allows life throughout its different seasons.

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