Water Properties

Water has special features that allow life on the planet, including , its great ability to dissolve substances, in addition to containing organic and inorganic nutrients, is found in greater quantity in liquid form, essential aspects of living things.
Compared to air, it has higher values for density, light-resistance, and specific heat.

The Structure of the Water Molecule

The water formula, H 2 O, indicates that it is composed of two hydrogen atoms and one oxygen . These atoms unequally share the electrons, creating a polarity (positive and negative charges).

In other words, the water molecule is polar and so the molecules bond through very strong hydrogen bridges.

Water Properties

Water in nature can be found in the solid state on glaciers in very cold regions, in the vapor state forming the atmosphere and clouds, or as liquid in rivers, seas and other aquatic bodies.

The most abundant form in nature, under normal conditions of temperature and pressure, is liquid thanks to its chemical structure, besides having a high boiling point (only boils at 100 °).

These characteristics of the water molecule influence various chemical and physical properties of water, such as surface tension, specific heat, solubility, and more, explained below.         

Physicochemical Properties of Water

Solubility

Water is an excellent solvent because it can dissolve huge amounts of substances. The substances that dissolve are called solutes and when mixed with the solvent forms a solution. This property is very important for living beings because they absorb nutrients (such as calcium, magnesium, etc.) dissolved in the water they drink.

Example : when salt is added to water and mixed forms a solution.

Water Properties

Surface tension is a physical property that results from the force of attraction between inner and surface molecules.

In internal molecules, as forces are in all directions they cancel each other out, while on the surface cohesion forces pull sideways and downward, thus making the surface look like an elastic film.

Water Properties

Example : An insect can walk on water because of surface tension. Many marine organisms live in this region of the film such as protozoa, bacteria, copepods, among others.

Density

Density is a measure of mass concentration in a certain volume , ie it determines how compact the substance is.

Water density varies and decreases at lower temperatures. This explains why ice floats on the surface of the water.

Water Properties

Example : the surface of lakes freezes due to this density difference from the interior of the lake.         

Specific Heat

The specific heat or thermal capacity of water is the amount of heat it takes to raise the temperature of 1g of a substance by 1 ° C.

Water has a high specific heat, which means that it can raise or lower its temperature considerably without changing its physical state, but otherwise it takes longer to happen compared to other substances.

Example : Because water occupies about 70% of the earth's surface, this property helps control the warming of the planet. Oceans store heat in warm weather that is released in cold weather.

Latent Heat

Represents the amount of heat required for the substance to change physical state. The latent heat of vaporization and melting of water is very high so that it prevents it from freezing or evaporating too quickly.

Example : The high latent heat of melting water does not allow it to freeze quickly, thus preventing organisms in cold environments from freezing.

Learn more:

  • Water Physical States
  • Water Cycle
  • Calorimetry
  • Drinking Water

Human Consumption : Drinking Water

The properties of water intended for human consumption must follow the quality standards to be a drinking water, these parameters are called potability.

Thus, the limit amounts of certain substances that are harmful to health, such as mercury, lead, cadmium, as well as pesticides, disinfectants, among others, are defined.

It is also determined the limit of microorganisms, fecal coliforms, and organoleptic characteristics such as turbidity (how turbid the water is), the intensity of odor and taste.

The Ministry of Health published Ordinance No. 2914 of December 2011, which " Provides for the control and surveillance procedures of drinking water quality and its potability standard."

This ordinance defines drinking water as "" intended for food intake, preparation and production and personal hygiene, whatever its origin ". These standards apply only to water from the water supply and not to mineral waters.