We all know how vital water is for the survival of living beings. Scientists have been probing Mars for decades together, just to find the slightest presence of water. Just last November, NASA stated that it found water on the moon, thereby paving a new path for development of lunar space station. So why all this hype about water? Why are scientists diligently carrying out all kinds of experiments to find water on other planets or satellites? It's because water signifies life! Water is inevitable for the existence of life, simply because it makes a large part of an organism's body. Water in a way acts as a liquid skeleton to the body and prevents the body constituents from falling apart. Physical properties of a substance deal with its appearance, however, chemical properties are properties used in chemistry to denote the state of the substance. In this article, we will have a look at only water chemical properties.
Chemical Properties of Water
The chemical description of water is H2O, which means that water is formed by the combination of two hydrogen atoms and oneoxygen atom. Hydrogen atom weighs one-sixteenth of an oxygen atom, thus in water molecule, 88.8% of weight is from oxygen, while 11.2% belongs to hydrogen.
Though overall water has a neutral charge, it tends to be slightly positive on the hydrogen side and slightly negative on oxygen side. The electrostatic bond formed between the slightly positive hydrogen ion of water molecule and other negative ions or polar molecules is termed as hydrogen bond.
Water has the capacity to dissolve more substances than any other liquid, thus, is called universal solvent. The universal solvent quality enables water to take other valuable minerals, nutrients or chemicals with them wherever they go. The polar bonds in water molecule make it a universal solvent.
Substances dissolving readily in water are called hydrophilic compounds. They consist of ions or polar molecules that use electrical charge effects to attract water molecules. The water molecules surround these polar molecules and carry them into the solution, thereby dissolving them. For example, ionic substances like sodium chloride dissolve in water, as the positive sodium ions and negative chlorine ions of sodium chloride get attracted to the polar water molecules.
Molecules with prevailing nonpolar bonds are the ones that are mostly insoluble in water and are called hydrophobic compounds. Hydrocarbons containing C-H bonds are examples of hydrophobic compounds. This is because the intensity with which water molecules are attracted to C-H bonds, is far lesser than the intensity towards other water molecules. Hence, water molecules do not carry these hydrocarbons into the solution.
The pH scale runs from 1 to 14, wherein ph 1-6 refers to acidic pH, while pH 8-14 refers to basic pH. At pH 7, a chemical is known to be neutral. The pH of a chemical substance is determined by the amount of hydrogen atoms in it. Thus, a chemical compound with high pH has higher number of hydrogen atoms in its chemical composition and are called acids. Whereas compounds with lower pH contains lower number of hydrogen atoms and are called bases. The pH of water is neutral.
Water has the ability to act as both an acid (proton donor) as well as a base (proton acceptor). It acts as a base to acids stronger than itself and acts as an acid to bases stronger than itself. This amphoteric nature is clearly visible in the below reaction, wherein water molecule reacts with acid as a base.
H2O (l) + HCl (aq) ⇌ H3O++ Cl-
Water molecule also reacts with a strong base as an acid.
H2O (l) + NH3 (aq) ⇌ NH4+ + OH-
Another interesting water chemical property is that metals such as gold, silver, copper, tin, etc. do not react with water. Moreover, although salt water chemical properties differ from that of regular water, due to the different dissolved salts present in them, distilled water chemical properties are the same as chemical properties of water. Distilled water will only differ in their physical properties. Hope this article on water chemical properties was helpful!